netty 解决TCP粘包与拆包问题(三)

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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