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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