netty 解决TCP粘包与拆包问题(三)

时间：2023-03-08 17:03:56

今天使用netty的固定长度进行解码

固定长度解码的原理就是按照指定消息的长度对消息自动解码。

在netty实现中，只需要采用FiexedLengthFrameDecoder解码器即可...

以下是服务端代码

 package com.ming.netty.nio.stickpack;

 import java.net.InetSocketAddress;

 import io.netty.bootstrap.ServerBootstrap;

 import io.netty.channel.ChannelFuture;

 import io.netty.channel.ChannelInitializer;

 import io.netty.channel.ChannelOption;

 import io.netty.channel.EventLoopGroup;

 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.codec.string.StringDecoder;

 import io.netty.handler.logging.LogLevel;

 import io.netty.handler.logging.LoggingHandler;

 public class EchoServer {

     public void bind(String addr,int port) throws Exception{

         EventLoopGroup bossGroup=new NioEventLoopGroup();

         EventLoopGroup workGroup=new NioEventLoopGroup();

         try {

             ServerBootstrap server=new ServerBootstrap();

             server.group(bossGroup,workGroup)

                   .channel(NioServerSocketChannel.class)

                   .option(ChannelOption.SO_BACKLOG, 100)

                   .handler(new LoggingHandler(LogLevel.INFO))

                   .childHandler(new ChannelInitializer<SocketChannel>() {

                     @Override

                     protected void initChannel(SocketChannel sc) throws Exception {

                         sc.pipeline().addLast(new FixedLengthFrameDecoder(50));//FixedLengthFrameDecoder 这个类就是固定长度解码器，意思就是将消息指定长度进行解码

                         sc.pipeline().addLast(new StringDecoder());

                         sc.pipeline().addLast(new EchoServerHandler());

                     }

                 });

             ChannelFuture f=server.bind(new InetSocketAddress(addr, port)).sync();

             System.out.println("启动服务器:"+f.channel().localAddress());

             //等等服务器端监听端口关闭

             f.channel().closeFuture().sync();

         } catch (Exception e) {

             e.printStackTrace();

         }finally{

             bossGroup.shutdownGracefully();

             workGroup.shutdownGracefully();

         }

     }

     public static void main(String[] args) throws Exception{

         new EchoServer().bind("192.168.1.108", 8500);

     }

 }
 package com.ming.netty.nio.stickpack;

 import io.netty.buffer.ByteBuf;

 import io.netty.buffer.Unpooled;

 import io.netty.channel.ChannelHandlerAdapter;

 import io.netty.channel.ChannelHandlerContext;

 public class EchoServerHandler extends ChannelHandlerAdapter{

     int count=0;

     @Override

     public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

         String body=(String)msg;

         System.out.println("服务器收到"+(++count)+"次客户端消息，消息是:"+body);

         body+="$_";

         ByteBuf rep=Unpooled.copiedBuffer(body.getBytes());

         ctx.writeAndFlush(rep);

     }

     @Override

     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {

         cause.printStackTrace();

         ctx.close();

     }

 }

注意: FixedLengthFrameDecoder 这个类解码后，你客户端每次就会按照指定长度进行数据接收了，哈哈...例子中是50个长度的字符哈...

天天学习，天天进步。。。。。。

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