Netty中分隔符和定长解码器的应用

一.使用DelimiterBasedFrameDecoder自动完成以分隔符作为结束标志的解码

1.1 DelimiterBasedFrameDecoder服务端开发

1.1.1 EchoServer实现

import io.netty.bootstrap.ServerBootstrap;

import io.netty.buffer.ByteBuf;

import io.netty.buffer.Unpooled;

import io.netty.channel.ChannelFuture;

import io.netty.channel.ChannelInitializer;

import io.netty.channel.ChannelOption;

import io.netty.channel.EventLoopGroup;

importio.netty.channel.nio.NioEventLoopGroup;

importio.netty.channel.socket.SocketChannel;

import io.netty.channel.socket.nio.NioServerSocketChannel;

importio.netty.handler.codec.DelimiterBasedFrameDecoder;

importio.netty.handler.codec.LineBasedFrameDecoder;

importio.netty.handler.codec.string.StringDecoder;

import io.netty.handler.logging.LogLevel;

import io.netty.handler.logging.LoggingHandler;

/*

 * 利用DelimiterBasedFrameDecoder完成以分隔符作为码流结束的标识

 */

public class EchoServer {

        

         publicvoid bind(int port) throws Exception{

                   //配置服务端的NIO线程组

                   EventLoopGroupbossGroup =new NioEventLoopGroup();

                   EventLoopGroupworkerGroup =new NioEventLoopGroup();

         try{

                   //用于启动NIO服务器的辅助启动类，降低服务端的开发复杂度

                   ServerBootstrapb=new ServerBootstrap();

                   b.group(bossGroup,workerGroup).

                   channel(NioServerSocketChannel.class)

                   .option(ChannelOption.SO_BACKLOG,100)

                   .handler(newLoggingHandler(LogLevel.INFO))

                   .childHandler(newChannelInitializer<SocketChannel>() {

                            @Override

                            publicvoid initChannel(SocketChannel ch) throws Exception{

                                     ByteBufdelimiter=Unpooled.copiedBuffer("$_".getBytes());

                                     ch.pipeline().addLast(

                                                        newDelimiterBasedFrameDecoder(1024,delimiter)); // 单条消息最大长度：1024

                                     ch.pipeline().addLast(newStringDecoder());

                                     ch.pipeline().addLast(newEchoServerHandler());

                            }

                            });

                           

                  

                   //绑定端口，同步等待成功

                   ChannelFuturef=b.bind(port).sync();

                   //等待服务端监听端口关闭

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

        

                  

         }catch (Exception e) {

                   //TODO: handle exception

         }finally{

                   //优雅退出，释放线程池资源

                   bossGroup.shutdownGracefully();

                   workerGroup.shutdownGracefully();

         }

        

         }

 

        

         publicstatic void main(String[] args) throws Exception{

                   intport=8080;

                   if(args!=null&&args.length>0){

                            try{

                                     port=Integer.valueOf(args[0]);

                            }catch (NumberFormatException e) {

                                     //TODO: handle exception

                            }

                   }

                   newEchoServer().bind(port);

         }}

1.1.2 EchoServerHandler实现

import io.netty.buffer.ByteBuf;

import io.netty.buffer.Unpooled;

import io.netty.channel.ChannelHandlerAdapter;

import io.netty.channel.ChannelHandlerContext;

/*

 * 利用LineBasedFrameDecoder解决TCP粘包问题

 */

public classEchoServerHandler extends ChannelHandlerAdapter{

     

   int counter =0;

   @Override

   public voidchannelRead(ChannelHandlerContext ctx,Object msg)throwsException{

     

      Stringbody=(String)msg;

      System.out.println("This is"+++counter+"times receive client: ["+body+"]" );

      body+="$_";

         ByteBufecho=Unpooled.copiedBuffer(body.getBytes());

         ctx.writeAndFlush(echo);

   }

 

  

   @Override

   public voidexceptionCaught(ChannelHandlerContext ctx,Throwable cause){

      cause.printStackTrace();

      ctx.close();  // 发生异常，关闭链路

   }

}

1.2 DelimitedBasedFrameDecoder客户端开发

1.2.1 EchoClient实现

import client.TimeClient;

import io.netty.bootstrap.Bootstrap;

import io.netty.buffer.ByteBuf;

import io.netty.buffer.Unpooled;

import io.netty.channel.ChannelFuture;

import io.netty.channel.ChannelInitializer;

import io.netty.channel.ChannelOption;

import io.netty.channel.EventLoopGroup;

importio.netty.channel.nio.NioEventLoopGroup;

importio.netty.channel.socket.SocketChannel;

importio.netty.channel.socket.nio.NioSocketChannel;

importio.netty.handler.codec.DelimiterBasedFrameDecoder;

importio.netty.handler.codec.string.StringDecoder;

 

public class EchoClient {

        

         publicvoid connect(int port,String host) throws Exception{

                   //配置客户端NIO线程组

                   EventLoopGroupgroup=new NioEventLoopGroup();

                   try{

                            Bootstrapb=new Bootstrap();

                            b.group(group).channel(NioSocketChannel.class)

                            .option(ChannelOption.TCP_NODELAY,true)

                            .handler(newChannelInitializer<SocketChannel>() {

                                     @Override

                                     publicvoid initChannel(SocketChannel ch) throws Exception{

                                               ByteBufdelimiter=Unpooled.copiedBuffer("$_".getBytes());

                                               ch.pipeline().addLast(newDelimiterBasedFrameDecoder(1024,delimiter));

                                               ch.pipeline().addLast(newStringDecoder());

                                               ch.pipeline().addLast(newEchoClientHandler());

                                     }

                            });

                            //发起异步连接操作

                            ChannelFuturef=b.connect(host,port).sync();

                            //等待客户端链路关闭

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

                   }catch (Exception e) {

                            //TODO: handle exception

                   }finally{

                            //优雅退出，释放NIO线程组

                            group.shutdownGracefully();

                   }

         }

        

         publicstatic void main(String[] args) throws Exception{

                   intport=8080;

                   if(args!=null&&args.length>0){

                            try{

                                     port=Integer.valueOf(args[0]);

                                    

                            }catch (NumberFormatException e) {

                                     //TODO: handle exception

                                    

                            }

                            newTimeClient().connect(port,"127.0.0.1");

                   }

         }

 

}

1.2.2 EchoClientHandler实现

import io.netty.buffer.Unpooled;

importio.netty.channel.ChannelHandlerAdapter;

importio.netty.channel.ChannelHandlerContext;

 

public class EchoClientHandler extendsChannelHandlerAdapter{

        private int counter;

        static final String ECHO_REQ="Welcome to Netty.$_";

        

        public EchoClientHandler(){

                 

        }

        

        @Override

        public void channelActive(ChannelHandlerContext ctx){

                 for(int i=0;i<10;i++){

                           ctx.writeAndFlush(Unpooled.copiedBuffer(ECHO_REQ.getBytes()));

                 }

        }

        

        public void channelRead(ChannelHandlerContext ctx,Object msg) throwsException{

                 ctx.flush();

        }

        

        @Override

        public voidexceptionCaught(ChannelHandlerContext ctx,Throwable cause){

                 cause.printStackTrace();

                 ctx.close();

        }

}

二.使用FiexLengthFrameDecoder定长解码器进行自动解码

2.1 FixLengthFrameDecoder服务的开发

2.1.1 EchoServer实现

package fixedlength;

import io.netty.bootstrap.ServerBootstrap;

import io.netty.buffer.ByteBuf;

import io.netty.buffer.Unpooled;

import io.netty.channel.ChannelFuture;

import io.netty.channel.ChannelInitializer;

import io.netty.channel.ChannelOption;

import io.netty.channel.EventLoopGroup;

importio.netty.channel.nio.NioEventLoopGroup;

importio.netty.channel.socket.SocketChannel;

importio.netty.channel.socket.nio.NioServerSocketChannel;

importio.netty.handler.codec.DelimiterBasedFrameDecoder;

import io.netty.handler.codec.FixedLengthFrameDecoder;

importio.netty.handler.codec.LineBasedFrameDecoder;

importio.netty.handler.codec.string.StringDecoder;

import io.netty.handler.logging.LogLevel;

importio.netty.handler.logging.LoggingHandler;

/*

 * 利用FixedLengthFrameDecoder固定解码长度

 */

public class EchoServer {

        

         publicvoid bind(int port) throws Exception{

                   //配置服务端的NIO线程组

                   EventLoopGroupbossGroup =new NioEventLoopGroup();

                   EventLoopGroupworkerGroup =new NioEventLoopGroup();

         try{

                   //用于启动NIO服务器的辅助启动类，降低服务端的开发复杂度

                   ServerBootstrapb=new ServerBootstrap();

                   b.group(bossGroup,workerGroup).

                   channel(NioServerSocketChannel.class)

                   .option(ChannelOption.SO_BACKLOG,100)

                   .handler(newLoggingHandler(LogLevel.INFO))

                   .childHandler(newChannelInitializer<SocketChannel>() {

                            @Override

                            publicvoid initChannel(SocketChannel ch) throws Exception{

                                     ByteBufdelimiter=Unpooled.copiedBuffer("$_".getBytes());

                                     ch.pipeline().addLast(

                                                        newFixedLengthFrameDecoder(20)); // 固定解码长度为20

                                     ch.pipeline().addLast(newStringDecoder());

                                     ch.pipeline().addLast(newEchoServerHandler());

                            }

                            });

                           

                  

                   //绑定端口，同步等待成功

                   ChannelFuturef=b.bind(port).sync();

                   //等待服务端监听端口关闭

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

        

                  

         }catch (Exception e) {

                   //TODO: handle exception

         }finally{

                   //优雅退出，释放线程池资源

                   bossGroup.shutdownGracefully();

                   workerGroup.shutdownGracefully();

         }

        

         }

 

        

         publicstatic void main(String[] args) throws Exception{

                   intport=8080;

                   if(args!=null&&args.length>0){

                            try{

                                     port=Integer.valueOf(args[0]);

                            }catch (NumberFormatException e) {

                                     //TODO: handle exception

                            }

                   }

                   newEchoServer().bind(port);

         }

 

}

2.1.2 EchoServerHandler实现

import io.netty.channel.ChannelHandlerAdapter;

import io.netty.channel.ChannelHandlerContext;

/*

 * 打印读取的消息

 */

public classEchoServerHandler extends ChannelHandlerAdapter{

         

   @Override

   public voidchannelRead(ChannelHandlerContext ctx,Object msg)throwsException{

      System.out.println("Receive client:["+msg+"]");

     

   }

   @Override

   public voidexceptionCaught(ChannelHandlerContext ctx,Throwable cause){

      cause.printStackTrace();

      ctx.close();  // 发生异常，关闭链路

   }

}

  利用FixedLengthFrameDecoder解码器，无论一次接受多少数据报，它都会按照构造函数中固定长度进行解码