深圳网站建设网络推广公司,上海官方最新消息,怎么做可以访问网站,wordpress文章阅读书文章目录 三. Netty 进阶1. 粘包与半包1.1 粘包现象服务端代码客户端代码 1.2 半包现象服务端代码客户端代码 1.3 现象分析粘包半包缘由滑动窗口MSS 限制Nagle 算法 1.4 解决方案方法1#xff0c;短链接方法2#xff0c;固定长度方法3#xff0c;固定分隔符方法4#xff0c… 文章目录 三. Netty 进阶1. 粘包与半包1.1 粘包现象服务端代码客户端代码 1.2 半包现象服务端代码客户端代码 1.3 现象分析粘包半包缘由滑动窗口MSS 限制Nagle 算法 1.4 解决方案方法1短链接方法2固定长度方法3固定分隔符方法4预设长度 2. 协议设计与解析2.1 为什么需要协议2.2 redis 协议举例2.3 http 协议举例2.4 自定义协议要素编解码器MessageCodecTestMessageCodec输出 什么时候可以加 Sharable 3. 聊天室案例3.1 聊天室业务介绍3.2 聊天室业务-登录3.3 聊天室业务-单聊3.4 聊天室业务-群聊3.5 聊天室业务-退出3.6 聊天室业务-空闲检测连接假死 三. Netty 进阶
1. 粘包与半包
1.1 粘包现象
服务端代码
Slf4j
public class HelloWorldServer {void start() {NioEventLoopGroup boss new NioEventLoopGroup(1);NioEventLoopGroup worker new NioEventLoopGroup();try {ServerBootstrap serverBootstrap new ServerBootstrap();serverBootstrap.channel(NioServerSocketChannel.class);serverBootstrap.group(boss, worker);serverBootstrap.childHandler(new ChannelInitializerSocketChannel() {Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {log.debug(connected {}, ctx.channel());super.channelActive(ctx);}Overridepublic void channelInactive(ChannelHandlerContext ctx) throws Exception {log.debug(disconnect {}, ctx.channel());super.channelInactive(ctx);}});}});ChannelFuture channelFuture serverBootstrap.bind(8080);log.debug({} binding..., channelFuture.channel());channelFuture.sync();log.debug({} bound..., channelFuture.channel());channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error(server error, e);} finally {boss.shutdownGracefully();worker.shutdownGracefully();log.debug(stoped);}}public static void main(String[] args) {new HelloWorldServer().start();}
}客户端代码
客户端代码希望发送 10 个消息每个消息是 16 字节
import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import lombok.extern.slf4j.Slf4j;Slf4j
public class HelloWorldClient {public static void main(String[] args) {NioEventLoopGroup worker new NioEventLoopGroup();try {Bootstrap bootstrap new Bootstrap();bootstrap.channel(NioSocketChannel.class);bootstrap.group(worker);bootstrap.handler(new ChannelInitializerSocketChannel() {Overrideprotected void initChannel(SocketChannel ch) throws Exception {log.debug(connected...);ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {// 会在连接 channel 建立成功之后会触发 active事件Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {log.debug(sending...);for (int i 0; i 10; i) {ByteBuf buffer ctx.alloc().buffer();buffer.writeBytes(new byte[]{0, 1, 2, 3, 4,5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15});ctx.writeAndFlush(buffer);}}});}});ChannelFuture channelFuture bootstrap.connect(127.0.0.1, 8080).sync();channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error(client error, e);} finally {worker.shutdownGracefully();}}
}
服务器端的某次输出可以看到一次就接收了 160 个字节而非分 10 次接收。而我们客户端是发了10次每次16字节这就是粘包现象。
// 客户端输出
/*
11:57:47 [DEBUG] [nioEventLoopGroup-2-1] c.z.a.HelloWorldClient - connetted...
11:57:47 [DEBUG] [nioEventLoopGroup-2-1] c.z.a.HelloWorldClient - sending...
*/// 服务器端输出
/*
11:57:08 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0x6e5efdad] binding...
11:57:08 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0x6e5efdad, L:/0:0:0:0:0:0:0:0:8080] bound...
11:57:47 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0xfaf43bd5, L:/127.0.0.1:8080 - R:/127.0.0.1:65248] REGISTERED
11:57:47 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0xfaf43bd5, L:/127.0.0.1:8080 - R:/127.0.0.1:65248] ACTIVE
11:57:47 [DEBUG] [nioEventLoopGroup-3-1] c.z.a.HelloWorldServer - connected [id: 0xfaf43bd5, L:/127.0.0.1:8080 - R:/127.0.0.1:65248]
11:57:47 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0xfaf43bd5, L:/127.0.0.1:8080 - R:/127.0.0.1:65248] READ: 160B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000010| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000020| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000030| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000040| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000050| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000060| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000070| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000080| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000090| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
-------------------------------------------------------------------------
11:57:47 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0xfaf43bd5, L:/127.0.0.1:8080 - R:/127.0.0.1:65248] READ COMPLETE*/1.2 半包现象
服务端代码
只添加serverBootstrap.option(ChannelOption.SO_RCVBUF, 10);这一行代码
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import lombok.extern.slf4j.Slf4j;Slf4j
public class HelloWorldServer {void start() {NioEventLoopGroup boss new NioEventLoopGroup(1);NioEventLoopGroup worker new NioEventLoopGroup();try {ServerBootstrap serverBootstrap new ServerBootstrap();// 为现象明显服务端修改一下接收缓冲区其它代码不变// 调整系统的接收缓冲区-即滑动窗口serverBootstrap.option(ChannelOption.SO_RCVBUF, 10);serverBootstrap.channel(NioServerSocketChannel.class);serverBootstrap.group(boss, worker);serverBootstrap.childHandler(new ChannelInitializerSocketChannel() {Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {log.debug(connected {}, ctx.channel());super.channelActive(ctx);}Overridepublic void channelInactive(ChannelHandlerContext ctx) throws Exception {log.debug(disconnect {}, ctx.channel());super.channelInactive(ctx);}});}});ChannelFuture channelFuture serverBootstrap.bind(8080);log.debug({} binding..., channelFuture.channel());channelFuture.sync();log.debug({} bound..., channelFuture.channel());channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error(server error, e);} finally {boss.shutdownGracefully();worker.shutdownGracefully();log.debug(stoped);}}public static void main(String[] args) {new HelloWorldServer().start();}
}客户端代码
客户端没有任何代码变动
Slf4j
public class HelloWorldClient {public static void main(String[] args) {NioEventLoopGroup worker new NioEventLoopGroup();try {Bootstrap bootstrap new Bootstrap();bootstrap.channel(NioSocketChannel.class);bootstrap.group(worker);bootstrap.handler(new ChannelInitializerSocketChannel() {Overrideprotected void initChannel(SocketChannel ch) throws Exception {log.debug(connected...);ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {// 会在连接 channel 建立成功之后会触发 active事件Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {log.debug(sending...);for (int i 0; i 10; i) {ByteBuf buffer ctx.alloc().buffer();buffer.writeBytes(new byte[]{0, 1, 2, 3, 4,5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15});ctx.writeAndFlush(buffer);}}});}});ChannelFuture channelFuture bootstrap.connect(127.0.0.1, 8080).sync();channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error(client error, e);} finally {worker.shutdownGracefully();}}
}输出如下可以看到客户端发了10次每次16字节的消息但是服务端分几次接受了36B、50B、50B、24B加起来共160字节。
只要是使用TCP协议那就会出现粘包和半包问题
// 客户端输出
/*
12:10:42 [DEBUG] [nioEventLoopGroup-2-1] c.z.a.HelloWorldClient - connected...
12:10:42 [DEBUG] [nioEventLoopGroup-2-1] c.z.a.HelloWorldClient - sending...
*/// 服务端输出
/*
12:10:32 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0xdafb9db3] binding...
12:10:32 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0xdafb9db3, L:/0:0:0:0:0:0:0:0:8080] bound...
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] REGISTERED
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] ACTIVE
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] c.z.a.HelloWorldServer - connected [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450]
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ: 36B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000010| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000020| 00 01 02 03 |.... |
-------------------------------------------------------------------------
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ COMPLETE
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ: 50B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 00 01 02 03 |................|
|00000010| 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 00 01 02 03 |................|
|00000020| 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 00 01 02 03 |................|
|00000030| 04 05 |.. |
-------------------------------------------------------------------------
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ COMPLETE
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ: 50B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 06 07 08 09 0a 0b 0c 0d 0e 0f 00 01 02 03 04 05 |................|
|00000010| 06 07 08 09 0a 0b 0c 0d 0e 0f 00 01 02 03 04 05 |................|
|00000020| 06 07 08 09 0a 0b 0c 0d 0e 0f 00 01 02 03 04 05 |................|
|00000030| 06 07 |.. |
-------------------------------------------------------------------------
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ COMPLETE
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ: 24B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 08 09 0a 0b 0c 0d 0e 0f 00 01 02 03 04 05 06 07 |................|
|00000010| 08 09 0a 0b 0c 0d 0e 0f |........ |
-------------------------------------------------------------------------
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ COMPLETE
12:12:26 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ COMPLETE
12:12:26 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] EXCEPTION: java.io.IOException: 远程主机强迫关闭了一个现有的连接。*/注意 serverBootstrap.option(ChannelOption.SO_RCVBUF, 10) 影响的底层接收缓冲区即滑动窗口大小仅决定了 netty 读取的最小单位netty 实际每次读取的一般是它的整数倍 1.3 现象分析
粘包 现象发送 abc def接收 abcdef 原因 应用层应用层面接收方 ByteBuf 设置太大Netty 默认 1024滑动窗口TCP层面假设发送方 256 bytes 表示一个完整报文但由于接收方处理不及时且窗口大小足够大这 256 bytes 字节就会缓冲在接收方的滑动窗口中当滑动窗口中缓冲了多个报文就会粘包Nagle 算法TCP层面会造成粘包因为报文头也占据一定的大小如果携带的实际数据较小那显然不划算因此会攒够了一批量数据然后发送过去因此也会造成粘包
半包
现象发送 abcdef接收 abc def原因 应用层应用层面接收方 ByteBuf 小于实际发送数据量滑动窗口TCP层面假设接收方的窗口只剩了 128 bytes发送方的报文大小是 256 bytes这时放不下了只能先发送前 128 bytes等待 ack 后才能发送剩余部分这就造成了半包MSS 限制链路层面当发送的数据超过 MSS 限制后会将数据切分发送就会造成半包
本质是因为 TCP 是流式协议消息无边界
缘由
滑动窗口 TCP 以一个段segment为单位每发送一个段就需要进行一次确认应答ack处理但如果这么做缺点是包的往返时间越长性能就越差因为tcp协议是可靠的传输协议因此需要保证1次请求1次应答但是如果等到上一次请求得到应答再发送下一次请求那效率显然就很低因此下面引入了滑动窗口来解决这个问题 [外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-leJ1X8om-1690552927974)(assets/0049.png)] 为了解决此问题引入了窗口概念窗口大小即决定了无需等待应答而可以继续发送的数据最大值 [外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-c4Pwo8wB-1690552927976)(assets/0051.png)] 窗口实际就起到一个缓冲区的作用同时也能起到流量控制的作用 图中深色的部分即要发送的数据高亮的部分即窗口 窗口内的数据才允许被发送当应答未到达前窗口必须停止滑动 如果 1001~2000 这个段的数据 ack 回来了窗口就可以向前滑动 接收方也会维护一个窗口只有落在窗口内的数据才能允许接收 MSS 限制 链路层对一次能够发送的最大数据有限制这个限制称之为 MTUmaximum transmission unit不同的链路设备的 MTU 值也有所不同例如 以太网的 MTU 是 1500 FDDI光纤分布式数据接口的 MTU 是 4352 本地回环地址的 MTU 是 65535 - 本地测试不走网卡 MSS 是最大段长度maximum segment size它是 MTU 刨去 tcp 头和 ip 头后剩余能够作为数据传输的字节数 ipv4 tcp 头占用 20 bytesip 头占用 20 bytes因此以太网 MSS 的值为 1500 - 40 1460 TCP 在传递大量数据时会按照 MSS 大小将数据进行分割发送 MSS 的值在三次握手时通知对方自己 MSS 的值然后在两者之间选择一个小值作为 MSS Nagle 算法 即使发送一个字节也需要加入 tcp 头和 ip 头也就是总字节数会使用 41 bytes非常不经济。因此为了提高网络利用率tcp 希望尽可能发送足够大的数据这就是 Nagle 算法产生的缘由该算法是指发送端即使还有应该发送的数据但如果这部分数据很少的话则进行延迟发送 如果 SO_SNDBUF 的数据达到 MSS则需要发送如果 SO_SNDBUF 中含有 FIN表示需要连接关闭这时将剩余数据发送再关闭如果 TCP_NODELAY true则需要发送已发送的数据都收到 ack 时则需要发送上述条件不满足但发生超时一般为 200ms则需要发送除上述情况延迟发送 1.4 解决方案
短链接发一个包建立一次连接这样连接建立到连接断开之间就是消息的边界缺点效率太低每一条消息采用固定长度缺点浪费空间每一条消息采用分隔符例如 \n缺点需要转义每一条消息分为 head 和 bodyhead 中包含 body 的长度
方法1短链接
以解决粘包为例
public class HelloWorldClient {static final Logger log LoggerFactory.getLogger(HelloWorldClient.class);public static void main(String[] args) {// 分 10 次发送for (int i 0; i 10; i) {send();}}private static void send() {NioEventLoopGroup worker new NioEventLoopGroup();try {Bootstrap bootstrap new Bootstrap();bootstrap.channel(NioSocketChannel.class);bootstrap.group(worker);bootstrap.handler(new ChannelInitializerSocketChannel() {Overrideprotected void initChannel(SocketChannel ch) throws Exception {log.debug(conneted...);ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {log.debug(sending...);ByteBuf buffer ctx.alloc().buffer();buffer.writeBytes(new byte[]{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15});ctx.writeAndFlush(buffer);// 发完即关ctx.channel().close();}});}});ChannelFuture channelFuture bootstrap.connect(localhost, 8080).sync();channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error(client error, e);} finally {worker.shutdownGracefully();}}
}输出略 半包用这种办法还是解决不了因为接收方的缓冲区大小是有限的可再服务端通过如下方式调整netty的接收缓冲区查看还是会出现半包现象serverBootstrap.childOption(ChannelOption.RCVBUF_ALLOCATOR, new AdaptiveRecvByteBufAllocator(16, 16, 16)); 方法2固定长度
客户端的操作就是一次发送一个100字节长度的消息, 其中每10个字节表示一条消息不够10个字节的补位凑够10个字节
服务端使用定长解码器每10个字节凑够1条消息才给到下一个handler
客户端代码
Slf4j
public class HelloWorldClient {public static void main(String[] args) {send();}private static void send() {NioEventLoopGroup worker new NioEventLoopGroup();try {Bootstrap bootstrap new Bootstrap();bootstrap.channel(NioSocketChannel.class);bootstrap.group(worker);bootstrap.handler(new ChannelInitializerSocketChannel() {Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {// 会在连接 channel 建立成功之后会触发 active事件Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {/*这里的操作就是发送一个100字节长度的消息, 其中每10个字节表示一条消息*/ByteBuf buf ctx.alloc().buffer();char c 0;Random r new Random();for (int i 0; i 10; i) {byte[] bytes fill10Bytes(c, r.nextInt(10) 1);c;buf.writeBytes(bytes);}ctx.writeAndFlush(buf);}});}});ChannelFuture channelFuture bootstrap.connect(127.0.0.1, 8080).sync();channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error(client error, e);} finally {worker.shutdownGracefully();}}// 填够10个字节public static byte[] fill10Bytes(char c, int len) {byte[] bytes new byte[10];Arrays.fill(bytes, (byte) _);for (int i 0; i len; i) {bytes[i] (byte) c;}System.out.println(new String(bytes));return bytes;}
}
服务端代码
Slf4j
public class HelloWorldServer {void start() {NioEventLoopGroup boss new NioEventLoopGroup(1);NioEventLoopGroup worker new NioEventLoopGroup();try {ServerBootstrap serverBootstrap new ServerBootstrap();// 为现象明显服务端修改一下接收缓冲区其它代码不变// (调整系统的接收缓冲区即滑动窗口)// serverBootstrap.option(ChannelOption.SO_RCVBUF, 10);// 调整netty的接收缓冲区// serverBootstrap.childOption(ChannelOption.RCVBUF_ALLOCATOR,// new AdaptiveRecvByteBufAllocator(16, 16, 16));serverBootstrap.channel(NioServerSocketChannel.class);serverBootstrap.group(boss, worker);serverBootstrap.childHandler(new ChannelInitializerSocketChannel() {Overrideprotected void initChannel(SocketChannel ch) throws Exception {// 注意顺序: 要先添加定长的解码处理器, 再添加日志处理器ch.pipeline().addLast(new FixedLengthFrameDecoder(10));ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));}});ChannelFuture channelFuture serverBootstrap.bind(8080);log.debug({} binding..., channelFuture.channel());channelFuture.sync();log.debug({} bound..., channelFuture.channel());channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error(server error, e);} finally {boss.shutdownGracefully();worker.shutdownGracefully();log.debug(stoped);}}public static void main(String[] args) {new HelloWorldServer().start();}
}客户端输出可以看到客户端输出一次写入了100个字节
Connected to the target VM, address: 127.0.0.1:50935, transport: socket
13:51:29 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0xdc9dffac] REGISTERED
13:51:29 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0xdc9dffac] CONNECT: /127.0.0.1:8080
13:51:29 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0xdc9dffac, L:/127.0.0.1:50973 - R:/127.0.0.1:8080] ACTIVE
000000____
111_______
2222222222
333333____
444_______
55________
6666666___
77777_____
8888______
99999_____
13:51:29 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0xdc9dffac, L:/127.0.0.1:50973 - R:/127.0.0.1:8080] WRITE: 100B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 30 30 30 30 30 30 5f 5f 5f 5f 31 31 31 5f 5f 5f |000000____111___|
|00000010| 5f 5f 5f 5f 32 32 32 32 32 32 32 32 32 32 33 33 |____222222222233|
|00000020| 33 33 33 33 5f 5f 5f 5f 34 34 34 5f 5f 5f 5f 5f |3333____444_____|
|00000030| 5f 5f 35 35 5f 5f 5f 5f 5f 5f 5f 5f 36 36 36 36 |__55________6666|
|00000040| 36 36 36 5f 5f 5f 37 37 37 37 37 5f 5f 5f 5f 5f |666___77777_____|
|00000050| 38 38 38 38 5f 5f 5f 5f 5f 5f 39 39 39 39 39 5f |8888______99999_|
|00000060| 5f 5f 5f 5f |____ |
-------------------------------------------------------------------------
13:51:29 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0xdc9dffac, L:/127.0.0.1:50973 - R:/127.0.0.1:8080] FLUSH
服务端输出重点看服务端输出服务端每10个字节接收作为一条消息交给后面的handler处理并没有发生半包
13:51:21 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0xafdaf078] binding...
13:51:21 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0xafdaf078, L:/0:0:0:0:0:0:0:0:8080] bound...
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] REGISTERED
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] ACTIVE
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 30 30 30 30 30 30 5f 5f 5f 5f |000000____ |
-------------------------------------------------------------------------
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 31 31 31 5f 5f 5f 5f 5f 5f 5f |111_______ |
-------------------------------------------------------------------------
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 32 32 32 32 32 32 32 32 32 32 |2222222222 |
-------------------------------------------------------------------------
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 33 33 33 33 33 33 5f 5f 5f 5f |333333____ |
-------------------------------------------------------------------------
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 34 34 34 5f 5f 5f 5f 5f 5f 5f |444_______ |
-------------------------------------------------------------------------
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 35 35 5f 5f 5f 5f 5f 5f 5f 5f |55________ |
-------------------------------------------------------------------------
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 36 36 36 36 36 36 36 5f 5f 5f |6666666___ |
-------------------------------------------------------------------------
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 37 37 37 37 37 5f 5f 5f 5f 5f |77777_____ |
-------------------------------------------------------------------------
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 38 38 38 38 5f 5f 5f 5f 5f 5f |8888______ |
-------------------------------------------------------------------------
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 39 39 39 39 39 5f 5f 5f 5f 5f |99999_____ |
-------------------------------------------------------------------------
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ COMPLETE
缺点是数据包的大小不好把握
长度定的太大浪费长度定的太小对某些数据包又显得不够
方法3固定分隔符
服务端代码
服务端加入默认以 \n 或 \r\n 作为分隔符的处理器如果超出最大长度仍未出现分隔符则抛出异常
Slf4j
public class HelloWorldServer {void start() {NioEventLoopGroup boss new NioEventLoopGroup(1);NioEventLoopGroup worker new NioEventLoopGroup();try {ServerBootstrap serverBootstrap new ServerBootstrap();// 为现象明显服务端修改一下接收缓冲区其它代码不变// (调整系统的接收缓冲区即滑动窗口)// serverBootstrap.option(ChannelOption.SO_RCVBUF, 10);// 调整netty的接收缓冲区// serverBootstrap.childOption(ChannelOption.RCVBUF_ALLOCATOR,// new AdaptiveRecvByteBufAllocator(16, 16, 16));serverBootstrap.channel(NioServerSocketChannel.class);serverBootstrap.group(boss, worker);serverBootstrap.childHandler(new ChannelInitializerSocketChannel() {Overrideprotected void initChannel(SocketChannel ch) throws Exception {// 注意顺序: 要先添加基于分隔符的解码处理器, 再添加日志处理器ch.pipeline().addLast(new LineBasedFrameDecoder(1024));ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));}});ChannelFuture channelFuture serverBootstrap.bind(8080);log.debug({} binding..., channelFuture.channel());channelFuture.sync();log.debug({} bound..., channelFuture.channel());channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error(server error, e);} finally {boss.shutdownGracefully();worker.shutdownGracefully();log.debug(stoped);}}public static void main(String[] args) {new HelloWorldServer().start();}
}
客户端代码
客户端在每条消息之后加入 \n 分隔符
Slf4j
public class HelloWorldClient {public static void main(String[] args) {send();}private static void send() {NioEventLoopGroup worker new NioEventLoopGroup();try {Bootstrap bootstrap new Bootstrap();bootstrap.channel(NioSocketChannel.class);bootstrap.group(worker);bootstrap.handler(new ChannelInitializerSocketChannel() {Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {// 会在连接 channel 建立成功之后会触发 active事件Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {/*在每条消息后面加上1个\n, 来表示消息的分隔符*/ByteBuf buf ctx.alloc().buffer();char c 0;Random r new Random();for (int i 0; i 10; i) {StringBuilder sb makeString(c, r.nextInt(256) 1);buf.writeBytes(sb.toString().getBytes());c;}// 还是1次性写入bufctx.writeAndFlush(buf);}});}});ChannelFuture channelFuture bootstrap.connect(127.0.0.1, 8080).sync();channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error(client error, e);} finally {worker.shutdownGracefully();}}public static StringBuilder makeString(char c, int len) {StringBuilder sb new StringBuilder(len 2);for (int i 0; i len; i) {sb.append(c);}sb.append(\n);return sb;}
}客户端输出
14:27:28 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x45f4846a] REGISTERED
14:27:28 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x45f4846a] CONNECT: /127.0.0.1:8080
14:27:28 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x45f4846a, L:/127.0.0.1:54341 - R:/127.0.0.1:8080] ACTIVE
14:27:28 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x45f4846a, L:/127.0.0.1:54341 - R:/127.0.0.1:8080] WRITE: 1445B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000010| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000020| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000030| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000040| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000050| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000060| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000070| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000080| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000090| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000a0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000b0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000c0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000d0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000e0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000f0| 30 30 30 30 0a 31 31 31 31 31 31 31 31 31 31 31 |0000.11111111111|
|00000100| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000110| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000120| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000130| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000140| 31 31 31 31 31 31 31 31 31 31 31 31 31 0a 32 32 |1111111111111.22|
|00000150| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000160| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000170| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000180| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000190| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000001a0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000001b0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000001c0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000001d0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000001e0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000001f0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000200| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000210| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000220| 32 32 0a 33 33 33 33 33 33 33 33 33 33 33 33 33 |22.3333333333333|
|00000230| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000240| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000250| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000260| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000270| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000280| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000290| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000002a0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000002b0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000002c0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000002d0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000002e0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000002f0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000300| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000310| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000320| 0a 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |.444444444444444|
|00000330| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000340| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000350| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000360| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000370| 34 34 0a 35 35 35 35 35 35 35 35 35 35 35 35 35 |44.5555555555555|
|00000380| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|00000390| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|000003a0| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|000003b0| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|000003c0| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|000003d0| 35 35 35 35 35 35 35 0a 36 36 36 36 36 36 36 36 |5555555.66666666|
|000003e0| 36 36 36 36 36 36 0a 37 37 37 37 37 37 37 37 37 |666666.777777777|
|000003f0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000400| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000410| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000420| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000430| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000440| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000450| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000460| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000470| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000480| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000490| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000004a0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000004b0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000004c0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000004d0| 37 0a 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |7.88888888888888|
|000004e0| 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |8888888888888888|
|000004f0| 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |8888888888888888|
|00000500| 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |8888888888888888|
|00000510| 38 38 38 38 38 38 38 0a 39 39 39 39 39 39 39 39 |8888888.99999999|
|00000520| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000530| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000540| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000550| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000560| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000570| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000580| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000590| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|000005a0| 39 39 39 39 0a |9999. |
-------------------------------------------------------------------------
14:27:28 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x45f4846a, L:/127.0.0.1:54341 - R:/127.0.0.1:8080] FLUSH
服务端输出
14:27:25 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0xd4acc436] binding...
14:27:25 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0xd4acc436, L:/0:0:0:0:0:0:0:0:8080] bound...
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] REGISTERED
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] ACTIVE
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 244B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000010| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000020| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000030| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000040| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000050| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000060| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000070| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000080| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000090| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000a0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000b0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000c0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000d0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000e0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000f0| 30 30 30 30 |0000 |
-------------------------------------------------------------------------
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 88B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000010| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000020| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000030| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000040| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000050| 31 31 31 31 31 31 31 31 |11111111 |
-------------------------------------------------------------------------
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 212B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000010| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000020| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000030| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000040| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000050| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000060| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000070| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000080| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000090| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000000a0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000000b0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000000c0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000000d0| 32 32 32 32 |2222 |
-------------------------------------------------------------------------
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 253B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000010| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000020| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000030| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000040| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000050| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000060| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000070| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000080| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000090| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000000a0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000000b0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000000c0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000000d0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000000e0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000000f0| 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333 |
-------------------------------------------------------------------------
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 81B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000010| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000020| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000030| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000040| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000050| 34 |4 |
-------------------------------------------------------------------------
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 100B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|00000010| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|00000020| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|00000030| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|00000040| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|00000050| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|00000060| 35 35 35 35 |5555 |
-------------------------------------------------------------------------
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 14B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 36 36 36 36 36 36 36 36 36 36 36 36 36 36 |66666666666666 |
-------------------------------------------------------------------------
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 234B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000010| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000020| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000030| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000040| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000050| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000060| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000070| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000080| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000090| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000000a0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000000b0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000000c0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000000d0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000000e0| 37 37 37 37 37 37 37 37 37 37 |7777777777 |
-------------------------------------------------------------------------
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 69B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |8888888888888888|
|00000010| 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |8888888888888888|
|00000020| 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |8888888888888888|
|00000030| 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |8888888888888888|
|00000040| 38 38 38 38 38 |88888 |
-------------------------------------------------------------------------
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 140B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000010| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000020| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000030| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000040| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000050| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000060| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000070| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000080| 39 39 39 39 39 39 39 39 39 39 39 39 |999999999999 |
-------------------------------------------------------------------------
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ COMPLETE
缺点处理字符数据比较合适但如果内容本身包含了分隔符字节数据常常会有此情况那么就会解析错误
方法4预设长度
在发送消息前先约定用定长字节表示接下来数据的长度
LengthFieldBasedFrameDecoder lengthFieldOffset - 长度字段偏移量 lengthFieldLength - 长度字段长度 lengthAdjustment - 长度字段为基准还要跳过几个字节才是内容 initialBytesTostrip - 从头剥离几个字节
// 最大长度长度偏移长度占用字节长度调整剥离字节数
ch.pipeline().addLast(new LengthFieldBasedFrameDecoder(1024, 0, 1, 0, 1));测试示例使用EmbeddedChannel模拟
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufAllocator;
import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;public class TestLengthFieldDecoder {public static void main(String[] args) {// 注意处理器的添加顺序EmbeddedChannel channel new EmbeddedChannel(new LengthFieldBasedFrameDecoder(1024, 0, 4, 1, 5),new LoggingHandler(LogLevel.DEBUG));// 4 个字节的内容长度 实际内容ByteBuf buffer ByteBufAllocator.DEFAULT.buffer();// 模拟对方发送过来消息send(buffer, Hello, world);send(buffer, Hi!);// 把消息写入channelchannel.writeInbound(buffer);}private static void send(ByteBuf buffer, String content) {// 实际内容byte[] bytes content.getBytes();// 实际内容长度int length bytes.length;// 写入内容长度buffer.writeInt(length);// 写入版本号buffer.writeByte(1);// 写入实际内容buffer.writeBytes(bytes);}
}
// 输出
/*
16:09:07 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] REGISTERED
16:09:07 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] ACTIVE
16:09:07 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] READ: 12B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 48 65 6c 6c 6f 2c 20 77 6f 72 6c 64 |Hello, world |
-------------------------------------------------------------------------
16:09:07 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] READ: 3B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 48 69 21 |Hi! |
-------------------------------------------------------------------------
16:09:07 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] READ COMPLETE
*/2. 协议设计与解析
2.1 为什么需要协议
TCP/IP 中消息传输基于流的方式没有边界。
协议的目的就是划定消息的边界制定通信双方要共同遵守的通信规则
例如在网络上传输
下雨天留客天留我不留是中文一句著名的无标点符号句子在没有标点符号情况下这句话有数种拆解方式而意思却是完全不同所以常被用作讲述标点符号的重要性
一种解读
下雨天留客天留我不留另一种解读
下雨天留客天留我不留如何设计协议呢其实就是给网络传输的信息加上“标点符号”。但通过分隔符来断句不是很好因为分隔符本身如果用于传输那么必须加以区分。因此下面一种协议较为常用
定长字节表示内容长度 实际内容例如假设一个中文字符长度为 3按照上述协议的规则发送信息方式如下就不会被接收方弄错意思了
0f下雨天留客06天留09我不留小故事 很久很久以前一位私塾先生到一家任教。双方签订了一纸协议“无鸡鸭亦可无鱼肉亦可白菜豆腐不可少不得束修金”。此后私塾先生虽然认真教课但主人家则总是给私塾先生以白菜豆腐为菜丝毫未见鸡鸭鱼肉的款待。私塾先生先是很不解可是后来也就想通了主人把鸡鸭鱼肉的钱都会换为束修金的也罢。至此双方相安无事。 年关将至一个学年段亦告结束。私塾先生临行时也不见主人家为他交付束修金遂与主家理论。然主家亦振振有词“有协议为证——无鸡鸭亦可无鱼肉亦可白菜豆腐不可少不得束修金。这白纸黑字明摆着的你有什么要说的呢” 私塾先生据理力争“协议是这样的——无鸡鸭亦可无鱼肉亦可白菜豆腐不可少不得束修金。” 双方唇枪舌战你来我往真个是不亦乐乎 这里的束修金也作“束脩”应当是泛指教师应当得到的报酬 2.2 redis 协议举例
使用netty编写客户端连接redis并且发送set aaa bbbget aaa 这2个命令
Slf4j
public class TestRedis {/*set name zhangsan*3 3个元素 \r\n$3 第一个元素3个字节 \r\nset set 3个字节$4 第二个元素4个字节 \r\nnamename 4个字节$8 第三个元素8个字节 \r\nzhangsanzhangsan 8个字节*/public static void main(String[] args) {NioEventLoopGroup worker new NioEventLoopGroup();byte[] LINE new byte[]{13, 10};System.out.println(LINE_BYTES[0] \r);System.out.println(LINE_BYTES[1] \n);try {Bootstrap bootstrap new Bootstrap();bootstrap.channel(NioSocketChannel.class);bootstrap.group(worker);bootstrap.handler(new ChannelInitializerSocketChannel() {Overrideprotected void initChannel(SocketChannel ch) {ch.pipeline().addLast(new LoggingHandler());ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {// 会在连接 channel 建立成功后会触发 active 事件Overridepublic void channelActive(ChannelHandlerContext ctx) {// 执行命令: set aaa bbbset(ctx);// 执行命令: get aaaget(ctx);}private void get(ChannelHandlerContext ctx) {ByteBuf buf ctx.alloc().buffer();buf.writeBytes(*2.getBytes());buf.writeBytes(LINE);buf.writeBytes($3.getBytes());buf.writeBytes(LINE);buf.writeBytes(get.getBytes());buf.writeBytes(LINE);buf.writeBytes($3.getBytes());buf.writeBytes(LINE);buf.writeBytes(aaa.getBytes());buf.writeBytes(LINE);ctx.writeAndFlush(buf);}private void set(ChannelHandlerContext ctx) {ByteBuf buf ctx.alloc().buffer();buf.writeBytes(*3.getBytes());buf.writeBytes(LINE);buf.writeBytes($3.getBytes());buf.writeBytes(LINE);buf.writeBytes(set.getBytes());buf.writeBytes(LINE);buf.writeBytes($3.getBytes());buf.writeBytes(LINE);buf.writeBytes(aaa.getBytes());buf.writeBytes(LINE);buf.writeBytes($3.getBytes());buf.writeBytes(LINE);buf.writeBytes(bbb.getBytes());buf.writeBytes(LINE); // 注意最后面的这个\r\n也不能省略ctx.writeAndFlush(buf); }Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {ByteBuf buf (ByteBuf) msg;System.out.println(buf.toString(Charset.defaultCharset()));// 我觉得这里应该需要释放buf吧??}});}});ChannelFuture channelFuture bootstrap.connect(localhost, 6379).sync();channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error(client error, e);} finally {worker.shutdownGracefully(); // 优雅关闭}}
}
// 输出日志
/*12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1] REGISTERED
12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1] CONNECT: localhost/127.0.0.1:6379
12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1, L:/127.0.0.1:58542 - R:localhost/127.0.0.1:6379] ACTIVE
12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1, L:/127.0.0.1:58542 - R:localhost/127.0.0.1:6379] WRITE: 31B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 2a 33 0d 0a 24 33 0d 0a 73 65 74 0d 0a 24 33 0d |*3..$3..set..$3.|
|00000010| 0a 61 61 61 0d 0a 24 33 0d 0a 62 62 62 0d 0a |.aaa..$3..bbb.. |
-------------------------------------------------------------------------
12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1, L:/127.0.0.1:58542 - R:localhost/127.0.0.1:6379] FLUSH
12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1, L:/127.0.0.1:58542 - R:localhost/127.0.0.1:6379] WRITE: 22B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 2a 32 0d 0a 24 33 0d 0a 67 65 74 0d 0a 24 33 0d |*2..$3..get..$3.|
|00000010| 0a 61 61 61 0d 0a |.aaa.. |
-------------------------------------------------------------------------
12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1, L:/127.0.0.1:58542 - R:localhost/127.0.0.1:6379] FLUSH
12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1, L:/127.0.0.1:58542 - R:localhost/127.0.0.1:6379] READ: 14B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 2b 4f 4b 0d 0a 24 33 0d 0a 62 62 62 0d 0a |OK..$3..bbb.. |
-------------------------------------------------------------------------
OK
$3
bbb12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1, L:/127.0.0.1:58542 - R:localhost/127.0.0.1:6379] READ COMPLETE*/2.3 http 协议举例
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.http.*;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import lombok.extern.slf4j.Slf4j;Slf4j
public class TestHttp {public static void main(String[] args) throws InterruptedException {NioEventLoopGroup boss new NioEventLoopGroup(1);NioEventLoopGroup worker new NioEventLoopGroup();try {ServerBootstrap serverBootstrap new ServerBootstrap().group(boss, worker).channel(NioServerSocketChannel.class).childHandler(new ChannelInitializerSocketChannel() {Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));// 配置http编解码器包括编码、解码// 解码 - 把发向服务端的请求ByteBuf解码// 编码 - 把发给客户端的数据编码成ByteBuf, 以便写出字节数据// HttpServerCodec继承自CombinedChannelDuplexHandlerHttpRequestDecoder,// HttpResponseEncoderch.pipeline().addLast(new HttpServerCodec());// 注意写入的泛型, 表示该处理器只处理该类型的消息ch.pipeline().addLast(new SimpleChannelInboundHandlerHttpRequest() {Overrideprotected void channelRead0(ChannelHandlerContext ctx, HttpRequest msg) throws Exception {// 获取请求urilog.info(msg.uri());// 响应对象DefaultFullHttpResponse response new DefaultFullHttpResponse(msg.protocolVersion(), HttpResponseStatus.OK);byte[] content h1hello,world/h1.getBytes();response.content().writeBytes(content);// 告诉浏览器, 响应内容就这么长, 不然浏览器会一直傻傻的等待接收后面的内容// 网站图标位置一直在转圈圈response.headers().set(HttpHeaderNames.CONTENT_LENGTH, content.length);// 写回响应// 这个response将会经过HttpServerCodec出站处理器将它编码了// 再返回回去ctx.writeAndFlush(response);}});/*// 当浏览器发起1个get请求后, 该处理器的channelRead方法被调用了2次// - 第一次传过来的msg是 DefaultHttpRequest(decodeResult: success,version: HTTP/1.1)// - 第二次传过来的是 EmptyLastHttpContentch.pipeline().addLast(new ChannelInboundHandlerAdapter() {Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {log.info(接收到请求: {}, msg);// HttpServerCodec会把接收到的请求, // 分为 HttpRequest 和 HttpContent(对该handler进行了2次调用)// 如果只处理其中某一种类型的消息可以如上使用// SimpleChannelInboundHandler// 并指定泛型比如上面就指定了HttpRequestif (msg instanceof HttpRequest) { // 请求行 和 请求头log.info(HttpRequest msg: {}, msg);} else if (msg instanceof HttpContent) { // 请求体log.info(HttpContent msg: {}, msg);}}});*/}});ChannelFuture channelFuture serverBootstrap.bind(8080).sync();channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {e.printStackTrace();} finally {boss.shutdownGracefully();worker.shutdownGracefully();}}
}2.4 自定义协议要素
魔数用来在第一时间判定是否是无效数据包版本号可以支持协议的升级序列化算法消息正文到底采用哪种序列化反序列化方式可以由此扩展例如json、protobuf、hessian、jdk指令类型是登录、注册、单聊、群聊… 跟业务相关请求序号为了双工通信提供异步能力正文长度消息正文
编解码器
根据上面的要素设计一个登录请求消息和登录响应消息并使用 Netty 完成收发
MessageCodec
Slf4j
public class MessageCodec extends ByteToMessageCodecMessage {Overridepublic void encode(ChannelHandlerContext ctx, Message msg, ByteBuf out) throws Exception {// 1. 4 字节的魔数out.writeBytes(new byte[]{1, 2, 3, 4});// 2. 1 字节的版本,out.writeByte(1);// 3. 1 字节的序列化方式 jdk 0 , json 1out.writeByte(0);// 4. 1 字节的指令类型out.writeByte(msg.getMessageType());// 5. 4 个字节out.writeInt(msg.getSequenceId());// 无意义对齐填充为了满2^n固定字节数, 正好凑够16个固定字节数out.writeByte(0xff);/* 将Message对象先转为字节数组(使用ByteArrayOutputStream ObjectOutputStream),然后把字节数组写到ByteBuf中 */// 6. 获取内容的字节数组ByteArrayOutputStream bos new ByteArrayOutputStream();ObjectOutputStream oos new ObjectOutputStream(bos);oos.writeObject(msg);byte[] bytes bos.toByteArray();// 7. 长度out.writeInt(bytes.length);// 8. 写入内容out.writeBytes(bytes);log.info(message 编码完成...{}, msg);}Overrideprotected void decode(ChannelHandlerContext ctx, ByteBuf in, ListObject out) throws Exception {// 读取 4 字节的魔数读指针向后移动4位int magicNum in.readInt();// 读取 1 字节的版本byte version in.readByte();// 读取 1 字节的序列化方式byte serializerType in.readByte();// 读取 1 字节的指令类型byte messageType in.readByte();// 读取 4 个字节 序列idint sequenceId in.readInt();// 读取 无意义 的字节将读指针向后移动1位in.readByte();// 读取 长度int length in.readInt();// 使用读取到的长度创建字节数组byte[] bytes new byte[length];// 将ByteBuf读取到字节数组in.readBytes(bytes, 0, length);/* 这里将ByteBuf的数据, 通过jdk反序列化的方式, 转为java对象,那就要保证这个数据一定是对象完整的序列化字节数据,如果不是一个完整的数据即出现半包的情况, 那就废了。因此*/// jdk反序列化 将字节数组 转为 Message对象ObjectInputStream ois new ObjectInputStream(new ByteArrayInputStream(bytes));Message message (Message) ois.readObject();log.debug({}, {}, {}, {}, {}, {}, magicNum, version, serializerType, messageType, sequenceId, length);log.debug(message 解码完成{}, message);// 将消息添加到out集合当中out.add(message);}
}TestMessageCodec
Slf4j
public class TestMessageCodec {public static void main(String[] args) throws Exception {EmbeddedChannel channel new EmbeddedChannel(new LoggingHandler(),// 参数的含义数据的最大长度为1024个字节、从索引0开始,偏移12个字节开始,是实际内容长度信息、// 实际内容长度占4个字节、不做调整(即不偏移,实际内容长度后面开始就是实际内容)、// 不剥离前面的字节因为在MessageCodec中有解析前面的字节// 帧解码器解决粘包半包问题// 如果发现数据不完整(即发生了半包问题), 它是不会把消息传递给下一个处理器处理的,// 等数据完整了它才会把完整的消息发给下一个处理器// 此处可用来解决半包的问题: 也就是说, 实际内容长度可能有239个字节, 但是本次只收到了100个字节,// 那如果往后面读的话, 就读不满239个字节, 那就等接收到下一次消息后,// 一直到满了239个字节, 再把这个完整的消息, 传递给下一个handlernew LengthFieldBasedFrameDecoder(1024, 12, 4, 0, 0),// 自定义编解码器new MessageCodec());log.info(------------------测试编码-----------------);// 测试encodeLoginRequestMessage message new LoginRequestMessage(zhangsan, 123);// 向channel中写出数据MessageCodec会对message作编码处理写入到ByteBufchannel.writeOutbound(message);log.info(------------------测试解码-----------------);// 测试decode// 先使用MessageCodec将message写入到ByteBufByteBuf buf ByteBufAllocator.DEFAULT.buffer();new MessageCodec().encode(null, message, buf);// 将buf切片成2部分, 模拟半包(先接收100字节, 然后再接收剩下的字节),// 注意: 须使用LengthFieldBasedFrameDecoder处理半包问题ByteBuf s1 buf.slice(0, 100);ByteBuf s2 buf.slice(100, buf.readableBytes() - 100);s1.retain(); // 引用计数1即现在为2// 这个方法默认会释放bufrelease 1,接收半包后的数据时,buf被释放了就会报错(下面这句会报错)// 因此上面就使用了s1.retain()让引用计数1了channel.writeInbound(s1);channel.writeInbound(s2);}
}输出
观察下面的输出
编码的时候, 写出了224个字节解码的时候接受了2次第一次接受收了100个字节第二次接收了124个字节并且只出现了1次解码完成这说明在出现了半包的情况下LengthFieldBasedFrameDecoder帮助我们解决了半包问题并且它会接收一个完整的包后才会传给后面的handler可以留意一下在写出的时候第一行的字节数据 正好 符合 我们的编码规则哦
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] REGISTERED
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] ACTIVE
21:50:22 [INFO ] [main] c.i.a.c.TestMessageCodec - ------------------测试编码-----------------
21:50:22 [INFO ] [main] c.i.p.MessageCodec - message 编码完成...LoginRequestMessage(superMessage(sequenceId0, messageType0), usernamezhangsan, password123)
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] WRITE: 214B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 01 02 03 04 01 00 00 00 00 00 00 ff 00 00 00 c6 |................|
|00000010| ac ed 00 05 73 72 00 25 63 6e 2e 69 74 63 61 73 |....sr.%cn.itcas|
|00000020| 74 2e 6d 65 73 73 61 67 65 2e 4c 6f 67 69 6e 52 |t.message.LoginR|
|00000030| 65 71 75 65 73 74 4d 65 73 73 61 67 65 a0 3f 71 |equestMessage.?q|
|00000040| cb 31 45 b5 88 02 00 02 4c 00 08 70 61 73 73 77 |.1E.....L..passw|
|00000050| 6f 72 64 74 00 12 4c 6a 61 76 61 2f 6c 61 6e 67 |ordt..Ljava/lang|
|00000060| 2f 53 74 72 69 6e 67 3b 4c 00 08 75 73 65 72 6e |/String;L..usern|
|00000070| 61 6d 65 71 00 7e 00 01 78 72 00 19 63 6e 2e 69 |ameq.~..xr..cn.i|
|00000080| 74 63 61 73 74 2e 6d 65 73 73 61 67 65 2e 4d 65 |tcast.message.Me|
|00000090| 73 73 61 67 65 3d dd 19 a0 bc 07 47 cb 02 00 02 |ssage.....G....|
|000000a0| 49 00 0b 6d 65 73 73 61 67 65 54 79 70 65 49 00 |I..messageTypeI.|
|000000b0| 0a 73 65 71 75 65 6e 63 65 49 64 78 70 00 00 00 |.sequenceIdxp...|
|000000c0| 00 00 00 00 00 74 00 03 31 32 33 74 00 08 7a 68 |.....t..123t..zh|
|000000d0| 61 6e 67 73 61 6e |angsan |
-------------------------------------------------------------------------
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] FLUSH
21:50:22 [INFO ] [main] c.i.a.c.TestMessageCodec - ------------------测试解码-----------------
21:50:22 [INFO ] [main] c.i.p.MessageCodec - message 编码完成...LoginRequestMessage(superMessage(sequenceId0, messageType0), usernamezhangsan, password123)
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] READ: 100B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 01 02 03 04 01 00 00 00 00 00 00 ff 00 00 00 c6 |................|
|00000010| ac ed 00 05 73 72 00 25 63 6e 2e 69 74 63 61 73 |....sr.%cn.itcas|
|00000020| 74 2e 6d 65 73 73 61 67 65 2e 4c 6f 67 69 6e 52 |t.message.LoginR|
|00000030| 65 71 75 65 73 74 4d 65 73 73 61 67 65 a0 3f 71 |equestMessage.?q|
|00000040| cb 31 45 b5 88 02 00 02 4c 00 08 70 61 73 73 77 |.1E.....L..passw|
|00000050| 6f 72 64 74 00 12 4c 6a 61 76 61 2f 6c 61 6e 67 |ordt..Ljava/lang|
|00000060| 2f 53 74 72 |/Str |
-------------------------------------------------------------------------
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] READ COMPLETE
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] READ: 114B-------------------------------------------------| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
-------------------------------------------------------------------------
|00000000| 69 6e 67 3b 4c 00 08 75 73 65 72 6e 61 6d 65 71 |ing;L..usernameq|
|00000010| 00 7e 00 01 78 72 00 19 63 6e 2e 69 74 63 61 73 |.~..xr..cn.itcas|
|00000020| 74 2e 6d 65 73 73 61 67 65 2e 4d 65 73 73 61 67 |t.message.Messag|
|00000030| 65 3d dd 19 a0 bc 07 47 cb 02 00 02 49 00 0b 6d |e.....G....I..m|
|00000040| 65 73 73 61 67 65 54 79 70 65 49 00 0a 73 65 71 |essageTypeI..seq|
|00000050| 75 65 6e 63 65 49 64 78 70 00 00 00 00 00 00 00 |uenceIdxp.......|
|00000060| 00 74 00 03 31 32 33 74 00 08 7a 68 61 6e 67 73 |.t..123t..zhangs|
|00000070| 61 6e |an |
-------------------------------------------------------------------------
21:50:22 [DEBUG] [main] c.i.p.MessageCodec - 16909060, 1, 0, 0, 0, 198
21:50:22 [DEBUG] [main] c.i.p.MessageCodec - message 解码完成LoginRequestMessage(superMessage(sequenceId0, messageType0), usernamezhangsan, password123)
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] READ COMPLETE什么时候可以加 Sharable
当 handler 不保存状态时就可以安全地在多线程下被共享但要注意对于编解码器类不能继承 ByteToMessageCodec 或 CombinedChannelDuplexHandler 父类他们的构造方法对 Sharable 有限制如果能确保编解码器不会保存状态可以继承 MessageToMessageCodec 父类
Slf4j
ChannelHandler.Sharable
/*** 必须和 LengthFieldBasedFrameDecoder 一起使用确保接到的 ByteBuf 消息是完整的*/
public class MessageCodecSharable extends MessageToMessageCodecByteBuf, Message {Overrideprotected void encode(ChannelHandlerContext ctx, Message msg, ListObject outList) throws Exception {ByteBuf out ctx.alloc().buffer();// 1. 4 字节的魔数out.writeBytes(new byte[]{1, 2, 3, 4});// 2. 1 字节的版本,out.writeByte(1);// 3. 1 字节的序列化方式 jdk 0 , json 1out.writeByte(0);// 4. 1 字节的指令类型out.writeByte(msg.getMessageType());// 5. 4 个字节out.writeInt(msg.getSequenceId());// 无意义对齐填充out.writeByte(0xff);// 6. 获取内容的字节数组ByteArrayOutputStream bos new ByteArrayOutputStream();ObjectOutputStream oos new ObjectOutputStream(bos);oos.writeObject(msg);byte[] bytes bos.toByteArray();// 7. 长度out.writeInt(bytes.length);// 8. 写入内容out.writeBytes(bytes);outList.add(out);}Overrideprotected void decode(ChannelHandlerContext ctx, ByteBuf in, ListObject out) throws Exception {int magicNum in.readInt();byte version in.readByte();byte serializerType in.readByte();byte messageType in.readByte();int sequenceId in.readInt();in.readByte();int length in.readInt();byte[] bytes new byte[length];in.readBytes(bytes, 0, length);ObjectInputStream ois new ObjectInputStream(new ByteArrayInputStream(bytes));Message message (Message) ois.readObject();log.debug({}, {}, {}, {}, {}, {}, magicNum, version, serializerType, messageType, sequenceId, length);log.debug({}, message);out.add(message);}
}3. 聊天室案例
3.1 聊天室业务介绍
/*** 用户管理接口*/
public interface UserService {/*** 登录* param username 用户名* param password 密码* return 登录成功返回 true, 否则返回 false*/boolean login(String username, String password);
}/*** 会话管理接口*/
public interface Session {/*** 绑定会话* param channel 哪个 channel 要绑定会话* param username 会话绑定用户*/void bind(Channel channel, String username);/*** 解绑会话* param channel 哪个 channel 要解绑会话*/void unbind(Channel channel);/*** 获取属性* param channel 哪个 channel* param name 属性名* return 属性值*/Object getAttribute(Channel channel, String name);/*** 设置属性* param channel 哪个 channel* param name 属性名* param value 属性值*/void setAttribute(Channel channel, String name, Object value);/*** 根据用户名获取 channel* param username 用户名* return channel*/Channel getChannel(String username);
}/*** 聊天组会话管理接口*/
public interface GroupSession {/*** 创建一个聊天组, 如果不存在才能创建成功, 否则返回 null* param name 组名* param members 成员* return 成功时返回组对象, 失败返回 null*/Group createGroup(String name, SetString members);/*** 加入聊天组* param name 组名* param member 成员名* return 如果组不存在返回 null, 否则返回组对象*/Group joinMember(String name, String member);/*** 移除组成员* param name 组名* param member 成员名* return 如果组不存在返回 null, 否则返回组对象*/Group removeMember(String name, String member);/*** 移除聊天组* param name 组名* return 如果组不存在返回 null, 否则返回组对象*/Group removeGroup(String name);/*** 获取组成员* param name 组名* return 成员集合, 没有成员会返回 empty set*/SetString getMembers(String name);/*** 获取组成员的 channel 集合, 只有在线的 channel 才会返回* param name 组名* return 成员 channel 集合*/ListChannel getMembersChannel(String name);
}3.2 聊天室业务-登录
Slf4j
public class ChatServer {public static void main(String[] args) {NioEventLoopGroup boss new NioEventLoopGroup();NioEventLoopGroup worker new NioEventLoopGroup();LoggingHandler LOGGING_HANDLER new LoggingHandler(LogLevel.DEBUG);MessageCodecSharable MESSAGE_CODEC new MessageCodecSharable();try {ServerBootstrap serverBootstrap new ServerBootstrap();serverBootstrap.channel(NioServerSocketChannel.class);serverBootstrap.group(boss, worker);serverBootstrap.childHandler(new ChannelInitializerSocketChannel() {Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new ProcotolFrameDecoder());ch.pipeline().addLast(LOGGING_HANDLER);ch.pipeline().addLast(MESSAGE_CODEC);ch.pipeline().addLast(new SimpleChannelInboundHandlerLoginRequestMessage() {Overrideprotected void channelRead0(ChannelHandlerContext ctx, LoginRequestMessage msg) throws Exception {String username msg.getUsername();String password msg.getPassword();boolean login UserServiceFactory.getUserService().login(username, password);LoginResponseMessage message;if(login) {message new LoginResponseMessage(true, 登录成功);} else {message new LoginResponseMessage(false, 用户名或密码不正确);}ctx.writeAndFlush(message);}});}});Channel channel serverBootstrap.bind(8080).sync().channel();channel.closeFuture().sync();} catch (InterruptedException e) {log.error(server error, e);} finally {boss.shutdownGracefully();worker.shutdownGracefully();}}
}Slf4j
public class ChatClient {public static void main(String[] args) {NioEventLoopGroup group new NioEventLoopGroup();LoggingHandler LOGGING_HANDLER new LoggingHandler(LogLevel.DEBUG);MessageCodecSharable MESSAGE_CODEC new MessageCodecSharable();CountDownLatch WAIT_FOR_LOGIN new CountDownLatch(1);AtomicBoolean LOGIN new AtomicBoolean(false);try {Bootstrap bootstrap new Bootstrap();bootstrap.channel(NioSocketChannel.class);bootstrap.group(group);bootstrap.handler(new ChannelInitializerSocketChannel() {Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new ProcotolFrameDecoder());
// ch.pipeline().addLast(LOGGING_HANDLER);ch.pipeline().addLast(MESSAGE_CODEC);ch.pipeline().addLast(client handler, new ChannelInboundHandlerAdapter() {// 接收响应消息Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {log.debug(msg: {}, msg);if ((msg instanceof LoginResponseMessage)) {LoginResponseMessage response (LoginResponseMessage) msg;if (response.isSuccess()) {// 如果登录成功LOGIN.set(true);}// 唤醒 system in 线程WAIT_FOR_LOGIN.countDown();}}// 在连接建立后触发 active 事件Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {// 负责接收用户在控制台的输入负责向服务器发送各种消息new Thread(() - {Scanner scanner new Scanner(System.in);System.out.println(请输入用户名:);String username scanner.nextLine();System.out.println(请输入密码:);String password scanner.nextLine();// 构造消息对象LoginRequestMessage message new LoginRequestMessage(username, password);// 发送消息ctx.writeAndFlush(message);System.out.println(等待后续操作...);try {WAIT_FOR_LOGIN.await();} catch (InterruptedException e) {e.printStackTrace();}// 如果登录失败if (!LOGIN.get()) {ctx.channel().close();return;}while (true) {System.out.println();System.out.println(send [username] [content]);System.out.println(gsend [group name] [content]);System.out.println(gcreate [group name] [m1,m2,m3...]);System.out.println(gmembers [group name]);System.out.println(gjoin [group name]);System.out.println(gquit [group name]);System.out.println(quit);System.out.println();String command scanner.nextLine();String[] s command.split( );switch (s[0]){case send:ctx.writeAndFlush(new ChatRequestMessage(username, s[1], s[2]));break;case gsend:ctx.writeAndFlush(new GroupChatRequestMessage(username, s[1], s[2]));break;case gcreate:SetString set new HashSet(Arrays.asList(s[2].split(,)));set.add(username); // 加入自己ctx.writeAndFlush(new GroupCreateRequestMessage(s[1], set));break;case gmembers:ctx.writeAndFlush(new GroupMembersRequestMessage(s[1]));break;case gjoin:ctx.writeAndFlush(new GroupJoinRequestMessage(username, s[1]));break;case gquit:ctx.writeAndFlush(new GroupQuitRequestMessage(username, s[1]));break;case quit:ctx.channel().close();return;}}}, system in).start();}});}});Channel channel bootstrap.connect(localhost, 8080).sync().channel();channel.closeFuture().sync();} catch (Exception e) {log.error(client error, e);} finally {group.shutdownGracefully();}}
}3.3 聊天室业务-单聊
服务器端将 handler 独立出来
登录 handler
ChannelHandler.Sharable
public class LoginRequestMessageHandler extends SimpleChannelInboundHandlerLoginRequestMessage {Overrideprotected void channelRead0(ChannelHandlerContext ctx, LoginRequestMessage msg) throws Exception {String username msg.getUsername();String password msg.getPassword();boolean login UserServiceFactory.getUserService().login(username, password);LoginResponseMessage message;if(login) {SessionFactory.getSession().bind(ctx.channel(), username);message new LoginResponseMessage(true, 登录成功);} else {message new LoginResponseMessage(false, 用户名或密码不正确);}ctx.writeAndFlush(message);}
}单聊 handler
ChannelHandler.Sharable
public class ChatRequestMessageHandler extends SimpleChannelInboundHandlerChatRequestMessage {Overrideprotected void channelRead0(ChannelHandlerContext ctx, ChatRequestMessage msg) throws Exception {String to msg.getTo();Channel channel SessionFactory.getSession().getChannel(to);// 在线if(channel ! null) {channel.writeAndFlush(new ChatResponseMessage(msg.getFrom(), msg.getContent()));}// 不在线else {ctx.writeAndFlush(new ChatResponseMessage(false, 对方用户不存在或者不在线));}}
}3.4 聊天室业务-群聊
创建群聊
ChannelHandler.Sharable
public class GroupCreateRequestMessageHandler extends SimpleChannelInboundHandlerGroupCreateRequestMessage {Overrideprotected void channelRead0(ChannelHandlerContext ctx, GroupCreateRequestMessage msg) throws Exception {String groupName msg.getGroupName();SetString members msg.getMembers();// 群管理器GroupSession groupSession GroupSessionFactory.getGroupSession();Group group groupSession.createGroup(groupName, members);if (group null) {// 发生成功消息ctx.writeAndFlush(new GroupCreateResponseMessage(true, groupName 创建成功));// 发送拉群消息ListChannel channels groupSession.getMembersChannel(groupName);for (Channel channel : channels) {channel.writeAndFlush(new GroupCreateResponseMessage(true, 您已被拉入 groupName));}} else {ctx.writeAndFlush(new GroupCreateResponseMessage(false, groupName 已经存在));}}
}群聊
ChannelHandler.Sharable
public class GroupChatRequestMessageHandler extends SimpleChannelInboundHandlerGroupChatRequestMessage {Overrideprotected void channelRead0(ChannelHandlerContext ctx, GroupChatRequestMessage msg) throws Exception {ListChannel channels GroupSessionFactory.getGroupSession().getMembersChannel(msg.getGroupName());for (Channel channel : channels) {channel.writeAndFlush(new GroupChatResponseMessage(msg.getFrom(), msg.getContent()));}}
}加入群聊
ChannelHandler.Sharable
public class GroupJoinRequestMessageHandler extends SimpleChannelInboundHandlerGroupJoinRequestMessage {Overrideprotected void channelRead0(ChannelHandlerContext ctx, GroupJoinRequestMessage msg) throws Exception {Group group GroupSessionFactory.getGroupSession().joinMember(msg.getGroupName(), msg.getUsername());if (group ! null) {ctx.writeAndFlush(new GroupJoinResponseMessage(true, msg.getGroupName() 群加入成功));} else {ctx.writeAndFlush(new GroupJoinResponseMessage(true, msg.getGroupName() 群不存在));}}
}退出群聊
ChannelHandler.Sharable
public class GroupQuitRequestMessageHandler extends SimpleChannelInboundHandlerGroupQuitRequestMessage {Overrideprotected void channelRead0(ChannelHandlerContext ctx, GroupQuitRequestMessage msg) throws Exception {Group group GroupSessionFactory.getGroupSession().removeMember(msg.getGroupName(), msg.getUsername());if (group ! null) {ctx.writeAndFlush(new GroupJoinResponseMessage(true, 已退出群 msg.getGroupName()));} else {ctx.writeAndFlush(new GroupJoinResponseMessage(true, msg.getGroupName() 群不存在));}}
}查看成员
ChannelHandler.Sharable
public class GroupMembersRequestMessageHandler extends SimpleChannelInboundHandlerGroupMembersRequestMessage {Overrideprotected void channelRead0(ChannelHandlerContext ctx, GroupMembersRequestMessage msg) throws Exception {SetString members GroupSessionFactory.getGroupSession().getMembers(msg.getGroupName());ctx.writeAndFlush(new GroupMembersResponseMessage(members));}
}3.5 聊天室业务-退出
Slf4j
ChannelHandler.Sharable
public class QuitHandler extends ChannelInboundHandlerAdapter {// 当连接断开时触发 inactive 事件Overridepublic void channelInactive(ChannelHandlerContext ctx) throws Exception {SessionFactory.getSession().unbind(ctx.channel());log.debug({} 已经断开, ctx.channel());}// 当出现异常时触发Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {SessionFactory.getSession().unbind(ctx.channel());log.debug({} 已经异常断开 异常是{}, ctx.channel(), cause.getMessage());}
}3.6 聊天室业务-空闲检测
连接假死
原因
网络设备出现故障例如网卡机房等底层的 TCP 连接已经断开了但应用程序没有感知到仍然占用着资源。公网网络不稳定出现丢包。如果连续出现丢包这时现象就是客户端数据发不出去服务端也一直收不到数据就这么一直耗着应用程序线程阻塞无法进行数据读写
问题
假死的连接占用的资源不能自动释放向假死的连接发送数据得到的反馈是发送超时
服务器端解决
怎么判断客户端连接是否假死呢如果能收到客户端数据说明没有假死。因此策略就可以定为每隔一段时间就检查这段时间内是否接收到客户端数据没有就可以判定为连接假死
// 用来判断是不是 读空闲时间过长或 写空闲时间过长
// 5s 内如果没有收到 channel 的数据会触发一个 IdleState#READER_IDLE 事件
ch.pipeline().addLast(new IdleStateHandler(5, 0, 0));
// ChannelDuplexHandler 可以同时作为入站和出站处理器
ch.pipeline().addLast(new ChannelDuplexHandler() {// 用来触发特殊事件Overridepublic void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception{IdleStateEvent event (IdleStateEvent) evt;// 触发了读空闲事件if (event.state() IdleState.READER_IDLE) {log.debug(已经 5s 没有读到数据了);ctx.channel().close();}}
});客户端定时心跳
客户端可以定时向服务器端发送数据只要这个时间间隔小于服务器定义的空闲检测的时间间隔那么就能防止前面提到的误判客户端可以定义如下心跳处理器
// 用来判断是不是 读空闲时间过长或 写空闲时间过长
// 3s 内如果没有向服务器写数据会触发一个 IdleState#WRITER_IDLE 事件
ch.pipeline().addLast(new IdleStateHandler(0, 3, 0));
// ChannelDuplexHandler 可以同时作为入站和出站处理器
ch.pipeline().addLast(new ChannelDuplexHandler() {// 用来触发特殊事件Overridepublic void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception{IdleStateEvent event (IdleStateEvent) evt;// 触发了写空闲事件if (event.state() IdleState.WRITER_IDLE) {// log.debug(3s 没有写数据了发送一个心跳包);ctx.writeAndFlush(new PingMessage());}}
});
