目录
- 一、固定长度方式解决粘包问题(代码示例)
- 1.1、固定长度方式解决粘包问题的服务端代码示例
- 1.2、固定长度方式解决粘包问题的客户端代码示例
- 1.3、分别启动服务端,客户端,查看服务端结果输出
一、固定长度方式解决粘包问题(代码示例)
1.1、固定长度方式解决粘包问题的服务端代码示例
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让所有数据包长度固定(假设长度为 16 字节),服务器端加入
ch.pipeline().addLast(new FixedLengthFrameDecoder(16));
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服务端完整代码示例
package com.example.nettytest.netty.day5; 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.FixedLengthFrameDecoder; import io.netty.handler.logging.LogLevel; import io.netty.handler.logging.LoggingHandler; import lombok.extern.slf4j.Slf4j; /** * @description: 固定长度方式解决粘包 问题服务端示例 * @author: xz */ @Slf4j public class NettyFixLengthServer { public static void main(String[] args) { new NettyFixLengthServer().start(); } void start() { NioEventLoopGroup boss = new NioEventLoopGroup(1); NioEventLoopGroup worker = new NioEventLoopGroup(); try { ServerBootstrap serverBootstrap = new ServerBootstrap() .channel(NioServerSocketChannel.class) //调整 netty 的接受缓冲区(byteBuf) .childOption(ChannelOption.RCVBUF_ALLOCATOR,new AdaptiveRecvByteBufAllocator(16,16,16)) .group(boss, worker) .childHandler(new ChannelInitializer<SocketChannel>() { @Override protected void initChannel(SocketChannel ch) throws Exception { //设置定长解码器,位置必须再LoggingHandler之前,作用让所有数据包长度固定(假设长度为 16 字节) ch.pipeline().addLast(new FixedLengthFrameDecoder(16)); ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG)); ch.pipeline().addLast(new ChannelInboundHandlerAdapter() { //会在连接channel建立成功后,触发active事件 @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { log.debug("connected>>>>>>>>>>>>>>>> {}", ctx.channel()); super.channelActive(ctx); } @Override public 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"); } } }
1.2、固定长度方式解决粘包问题的客户端代码示例
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客户端代码示例
package com.example.nettytest.netty.day5; 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 io.netty.handler.logging.LogLevel; import io.netty.handler.logging.LoggingHandler; import lombok.extern.slf4j.Slf4j; import java.util.Arrays; import java.util.Random; /** * @description: 固定长度方式解决粘包 问题客户端示例 * @author: xz */ @Slf4j public class NettyFixLengthClient { public static void main(String[] args) { send(); } //剩余位置用下划线填充 public static byte[] fill10Bytes(char c,int len){ byte[] bytes = new byte[16]; Arrays.fill(bytes, (byte) '_'); for (int i = 0; i < len; i++) { bytes[i] = (byte) c; } System.out.println(new String(bytes)); return bytes; } private static void send() { NioEventLoopGroup worker = new NioEventLoopGroup(); try { Bootstrap bootstrap = new Bootstrap(); bootstrap.channel(NioSocketChannel.class); bootstrap.group(worker); bootstrap.handler(new ChannelInitializer<SocketChannel>() { @Override protected void initChannel(SocketChannel ch) throws Exception { log.debug("connetted..."); ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG)); ch.pipeline().addLast(new ChannelInboundHandlerAdapter() { @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { log.debug("sending..."); //设置ByteBuf ByteBuf buffer = ctx.alloc().buffer(); // 发送内容随机的数据包 Random r = new Random(); char c = '0'; for (int i = 0; i < 10; i++) { //剩余位置用下划线填充方法 byte[] bytes =fill10Bytes(c,r.nextInt(16)+1); c++; //写入到ByteBuf buffer.writeBytes(bytes); } ctx.writeAndFlush(buffer); } }); } }); ChannelFuture channelFuture = bootstrap.connect("localhost", 8080).sync(); channelFuture.channel().closeFuture().sync(); } catch (InterruptedException e) { log.error("client error", e); } finally { worker.shutdownGracefully(); } } }
1.3、分别启动服务端,客户端,查看服务端结果输出
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先启动服务端
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再启动客户端
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再次查看服务端
由输出结果可知,固定长度方式解决粘包问题的缺点: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。