（1）服务端Server
package com.xm.netty.demo04; import java.net.InetSocketAddress; import io.netty.bootstrap.ServerBootstrap; import io.netty.channel.Channel; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelInitializer; import io.netty.channel.EventLoopGroup; import io.netty.channel.nio.NioEventLoopGroup; import io.netty.channel.socket.nio.NioServerSocketChannel; import io.netty.handler.codec.FixedLengthFrameDecoder; import io.netty.handler.codec.string.StringDecoder; public class Server { private final int port; public Server(int port) { this.port = port; } public static void main(String[] args) { int port = 8989; try { new Server(port).start(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } private void start() throws InterruptedException { EventLoopGroup g1 = new NioEventLoopGroup(); EventLoopGroup g2 = new NioEventLoopGroup(); try { ServerBootstrap bootstrap = new ServerBootstrap(); bootstrap .group(g1,g2) .channel(NioServerSocketChannel.class) .localAddress(new InetSocketAddress( port)) .childHandler(new ChannelInitializer() { @Override protected void initChannel(Channel ch) throws Exception { ch.pipeline().addLast(new FixedLengthFrameDecoder(5)); ch.pipeline().addLast(new StringDecoder()); ch.pipeline().addLast(new ServerHandler()); } }); ChannelFuture future = bootstrap.bind().sync(); future.channel().closeFuture().sync(); } finally { g1.shutdownGracefully().sync(); g2.shutdownGracefully().sync(); } } }（2）服务端ServerHandler
package com.xm.netty.demo04; import java.time.LocalDateTime; import java.time.format.DateTimeFormatter; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelHandlerAdapter; import io.netty.channel.ChannelHandlerContext; import io.netty.util.CharsetUtil; public class ServerHandler extends ChannelHandlerAdapter { @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { String str = (String) msg; System.out.println("Server:"+str); ctx.writeAndFlush(Unpooled.copiedBuffer(str.getBytes())); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { cause.printStackTrace(); ctx.close(); } @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { System.out.println(DateTimeFormatter.ISO_LOCAL_DATE_TIME.format(LocalDateTime.now())+"一个客户端连接上服务器！"); } }（3）客户端Client
package com.xm.netty.demo04; import java.time.LocalDateTime; import java.time.format.DateTimeFormatter; import io.netty.bootstrap.Bootstrap; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelInitializer; import io.netty.channel.EventLoopGroup; import io.netty.channel.nio.NioEventLoopGroup; import io.netty.channel.socket.SocketChannel; import io.netty.channel.socket.nio.NioSocketChannel; import io.netty.handler.codec.FixedLengthFrameDecoder; import io.netty.handler.codec.string.StringDecoder; public class Client { private final int port; private final String host; public Client(int port, String host) { this.port = port; this.host = host; } public static void main(String[] args) { String host = "127.0.0.1"; int port = 8989; try { new Client(port, host).start(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } private void start() throws InterruptedException { EventLoopGroup group = new NioEventLoopGroup(); try { Bootstrap bootstrap = new Bootstrap(); bootstrap .group(group) .channel(NioSocketChannel.class) .remoteAddress(host, port) .handler(new ChannelInitializer<SocketChannel>() { @Override protected void initChannel(SocketChannel ch) throws Exception { ch.pipeline().addLast(new FixedLengthFrameDecoder(5)); ch.pipeline().addLast(new StringDecoder()); ch.pipeline().addLast(new ClientHandler()); } }); ChannelFuture future = bootstrap.connect().sync(); for(int i=123450;i<123460;i++) { String str = ""+i; future.channel().write(Unpooled.copiedBuffer(str.getBytes())); } future.channel().flush(); //future.channel().writeAndFlush(Unpooled.copiedBuffer("Hello Netty!".getBytes())); future.channel().closeFuture().sync(); } finally { group.shutdownGracefully().sync(); } } }（4）客户端ClientHandler
package com.xm.netty.demo04; import java.time.LocalDateTime; import java.time.format.DateTimeFormatter; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelHandlerAdapter; import io.netty.channel.ChannelHandlerContext; import io.netty.util.CharsetUtil; import io.netty.util.ReferenceCountUtil; public class ClientHandler extends ChannelHandlerAdapter { @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { try { String str = (String) msg; System.out.println("Client:"+str); } finally { ReferenceCountUtil.release(msg); } } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { cause.printStackTrace(); ctx.close(); } @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { System.out.println(DateTimeFormatter.ISO_LOCAL_DATE_TIME.format(LocalDateTime.now())+"已连接服务器！"); } }
运行结果截图
（1）服务端运行结果：
（2）客户端运行结果：