使用JDK的NIO类库开发程序步骤十分繁琐，而且容易出错。下面使用netty进行入门开发
本例使用netty 4.0的jar包（netty 5.0由于各种原因被原作者放弃）
netty jar包下载地址http://download.csdn.net/detail/hueason/9832925
package com.hueason.netty.n2.simpledemo; import io.netty.bootstrap.ServerBootstrap; import io.netty.channel.*; import io.netty.channel.nio.NioEventLoopGroup; import io.netty.channel.socket.SocketChannel; import io.netty.channel.socket.nio.NioServerSocketChannel; /** * Created by Administrator on 2017/4/20. */ public class TimeServer { public void bind(int port) throws Exception { //配置服务端的NIO线程组 EventLoopGroup bossGroup = new NioEventLoopGroup(); EventLoopGroup workerGroup = new NioEventLoopGroup(); try { ServerBootstrap b = new ServerBootstrap(); b.group(bossGroup, workerGroup) .channel(NioServerSocketChannel.class) .option(ChannelOption.SO_BACKLOG, 1024) .childHandler(new ChildChannelHandler()); //绑定端口，同步等待成功 完成之后会返回ChannelFuture用于异步操作的通知回调 ChannelFuture f = b.bind(port).sync(); //等待服务器监听端口关闭 f.channel().closeFuture().sync(); } finally { //优雅退出，释放线程池资源 bossGroup.shutdownGracefully(); workerGroup.shutdownGracefully(); } } private class ChildChannelHandler extends ChannelInitializer<SocketChannel> { @Override protected void initChannel(SocketChannel socketChannel) throws Exception { socketChannel.pipeline().addLast(new TimeServerHandler()); } } public static void main(String[] args) throws Exception { int port = 8080; if (args != null && args.length > 0){ try { port = Integer.valueOf(args[0]); } catch (NumberFormatException e) { e.printStackTrace(); } } new TimeServer().bind(port); } } package com.hueason.netty.n2.simpledemo; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelInboundHandlerAdapter; import java.util.Date; /** * Created by Administrator on 2017/4/20. */ public class TimeServerHandler extends ChannelInboundHandlerAdapter{ @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { ByteBuf buf = (ByteBuf) msg; byte[] req = new byte[buf.readableBytes()]; buf.readBytes(req); String body = new String(req,"UTF-8"); System.out.println("The time server receive order "+body); String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body)?new Date(System.currentTimeMillis()).toString():"BAD ORDER"; ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes()); ctx.write(resp); } @Override public void channelReadComplete(ChannelHandlerContext ctx) throws Exception { ctx.flush(); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { ctx.close(); } } 客户端 package com.hueason.netty.n2.simpledemo; import io.netty.bootstrap.Bootstrap; 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.NioSocketChannel; /** * Created by Administrator on 2017/4/26. */ public class TimeClient { public void connect(int port,String host) throws InterruptedException { //配置客户端NIO线程组 EventLoopGroup group = new NioEventLoopGroup(); try { Bootstrap b = new Bootstrap(); b.group(group).channel(NioSocketChannel.class) .option(ChannelOption.TCP_NODELAY,true) .handler(new ChannelInitializer<SocketChannel>() { @Override protected void initChannel(SocketChannel socketChannel) throws Exception { socketChannel.pipeline().addLast(new TimeClientHandler()); } }); //发起异步连接操作 ChannelFuture f = b.connect(host,port).sync(); //等待客户端链路关闭 f.channel().closeFuture().sync(); }finally { //优雅退出，释放NIO线程组 group.shutdownGracefully(); } } public static void main(String[] args) throws InterruptedException { int port = 8080; if(args != null && args.length >0){ port = Integer.valueOf(args[0]); } new TimeClient().connect(port,"127.0.0.1"); } } package com.hueason.netty.n2.simpledemo; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelInboundHandlerAdapter; import java.util.logging.Logger; /** * Created by Administrator on 2017/4/26. */ public class TimeClientHandler extends ChannelInboundHandlerAdapter { private static final Logger logger = Logger.getLogger(TimeClientHandler.class.getName()); private final ByteBuf firstMessage; public TimeClientHandler() { byte[] req = "QUERY TIME ORDER".getBytes(); this.firstMessage = Unpooled.buffer(req.length); firstMessage.writeBytes(req); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { //释放资源 logger.warning("Unexpected exception from downstream :" + cause.getMessage()); ctx.close(); } @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {//服务端返回应答时，该方法被调用 ByteBuf buf = (ByteBuf) msg; byte[] req = new byte[buf.readableBytes()]; buf.readBytes(req); String body = new String(req, "UTF-8"); System.out.println("Now is :" + body); } @Override public void channelActive(ChannelHandlerContext ctx) throws Exception {//客户端和服务端的TCP链路建立成功之后，Netty的NIO线程会调用该方法 ctx.writeAndFlush(firstMessage); } }相比于http://blog.csdn.net/hueason/article/details/71082084传统NIO开发难度大大降低
