Netty 4.0 demo

netty是一个异步，事件驱动的网络编程框架&工具，使用netty，可以快速开发从可维护，高性能的协议服务和客户端应用。是一个继mina之后，一个非常受欢迎的nio网络框架

netty4.x和之前的版本变化很大，包结构、对象和之前有很大不同。原来的包结构都是org.jboss.netty.*；目前改为了io.netty.* 的方式，其中，server，client的对象也和原来不同了

根据4.x的稳定版本4.0.14为蓝本，写一个hello world试试看。值得注意的是，4.0.x的beta版和final版本也有不小调整。很不幸的时，在4.x中刚出现的部分方法，到5.x中也将废弃。哎，苦逼的IT人。废话不说，看个4.x的例子吧

需要说明的是，我用的是netty4.0.13这个版本。因为netty有很多包，大家可以引入这个all包，其他的就全部包括了。

server端代码：

 package netty.test;

 import io.netty.bootstrap.ServerBootstrap;
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelFuture;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelPipeline;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.nio.NioEventLoopGroup;
 import io.netty.channel.socket.nio.NioServerSocketChannel;
 import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
 import io.netty.handler.codec.LengthFieldPrepender;
 import io.netty.handler.codec.string.StringDecoder;
 import io.netty.handler.codec.string.StringEncoder;
 import io.netty.util.CharsetUtil;

 public class MyNettyServer {
     private static final String IP = "127.0.0.1";
     private static final int PORT = 5656;
     private static final int BIZGROUPSIZE = Runtime.getRuntime().availableProcessors()*2;

     private static final int BIZTHREADSIZE = 100;
     private static final EventLoopGroup bossGroup = new NioEventLoopGroup(BIZGROUPSIZE);
     private static final EventLoopGroup workerGroup = new NioEventLoopGroup(BIZTHREADSIZE);
     public static void service() throws Exception {
         ServerBootstrap bootstrap = new ServerBootstrap();
         bootstrap.group(bossGroup, workerGroup);
         bootstrap.channel(NioServerSocketChannel.class);
         bootstrap.childHandler(new ChannelInitializer<Channel>() {

             @Override
             protected void initChannel(Channel ch) throws Exception {
                 // TODO Auto-generated method stub
                 ChannelPipeline pipeline = ch.pipeline();
                  pipeline.addLast(new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 4, 0, 4));
                     pipeline.addLast(new LengthFieldPrepender(4));
                     pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
                     pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
                     pipeline.addLast(new TcpServerHandler());
             }

         });
           ChannelFuture f = bootstrap.bind(IP, PORT).sync();
             f.channel().closeFuture().sync();
             System.out.println("TCP服务器已启动");
         }

         protected static void shutdown() {
             workerGroup.shutdownGracefully();
             bossGroup.shutdownGracefully();
         }

         public static void main(String[] args) throws Exception {
             System.out.println("开始启动TCP服务器...");
             MyNettyServer.service();
 //            HelloServer.shutdown();
         }
 }

对应的Handler对象 TcpServerHandler.java

 package netty.test;

 import io.netty.channel.ChannelHandlerAdapter;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;

 public class TcpServerHandler extends ChannelInboundHandlerAdapter {

     @Override
     public void channelRead(ChannelHandlerContext ctx, Object msg)
             throws Exception {
         // TODO Auto-generated method stub
         System.out.println("server receive message :"+ msg);
         ctx.channel().writeAndFlush("yes server already accept your message" + msg);
         ctx.close();
     }
     @Override
     public void channelActive(ChannelHandlerContext ctx) throws Exception {
         // TODO Auto-generated method stub
         System.out.println("channelActive>>>>>>>>");
     }
       @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
         System.out.println("exception is general");
     }
 }

客户端代码：

 package netty.test;

 import io.netty.bootstrap.Bootstrap;
 import io.netty.channel.ChannelFuture;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelOption;
 import io.netty.channel.ChannelPipeline;
 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.LengthFieldBasedFrameDecoder;
 import io.netty.handler.codec.LengthFieldPrepender;
 import io.netty.handler.codec.string.StringDecoder;
 import io.netty.handler.codec.string.StringEncoder;
 import io.netty.util.CharsetUtil;

 public class NettyClient implements Runnable {

     @Override
      public void run() {
             EventLoopGroup group = new NioEventLoopGroup();
             try {
                 Bootstrap b = new Bootstrap();
                 b.group(group);
                 b.channel(NioSocketChannel.class).option(ChannelOption.TCP_NODELAY, true);
                 b.handler(new ChannelInitializer<SocketChannel>() {
                     @Override
                     protected void initChannel(SocketChannel ch) throws Exception {
                         ChannelPipeline pipeline = ch.pipeline();
                         pipeline.addLast("frameDecoder", new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 4, 0, 4));
                         pipeline.addLast("frameEncoder", new LengthFieldPrepender(4));
                         pipeline.addLast("decoder", new StringDecoder(CharsetUtil.UTF_8));
                         pipeline.addLast("encoder", new StringEncoder(CharsetUtil.UTF_8));

                         pipeline.addLast("handler", new HelloClient());
                     }
                 });
                 for (int i = 0; i < 100000; i++) {
                      ChannelFuture f = b.connect("127.0.0.1", 5656).sync();
                      f.channel().writeAndFlush("hello Service!"+Thread.currentThread().getName()+":--->:"+i);
                      f.channel().closeFuture().sync();
                 }

             } catch (Exception e) {

             } finally {
                 group.shutdownGracefully();
             }
         }

         public static void main(String[] args) throws Exception {
             for (int i = 0; i < 1000; i++) {
                 new Thread(new NettyClient(),">>>this thread "+i).start();
             }
         }
 }

客户端对应的Handler对象代码，HelloClient.java

package netty.test;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

public class HelloClient extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        System.out.println("client接收到服务器返回的消息:" + msg);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        System.out.println("client exception is general");
    }
}