Netty

　　首先值得注意的是netty的jar包版本问题，版本不同，运用的方式也不同。我这里用4.0版本。

　　对于小白来说，netty到底是什么，我就没必要在这里阐明了，因为百度上比我描述的更全面。

　　这里就直接开门见山，代码走起。。。

 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;

 /**
  * 服务器
  */
 public class NettyServer {
     private final int port = 8989;

     public static void main(String[] args) {
         new NettyServer().nettyServer();
     }

     public void nettyServer(){
         EventLoopGroup bossGroup = new NioEventLoopGroup();
         EventLoopGroup workerGroup = new NioEventLoopGroup();

         try {
             ServerBootstrap serverBootStrap = new ServerBootstrap();

             serverBootStrap.group(bossGroup,workerGroup).channel(NioServerSocketChannel.class)
             .option(ChannelOption.SO_BACKLOG, 1024)
             .childHandler(new ChildChannelHandler());

             ChannelFuture futrue = serverBootStrap.bind(port).sync();
             futrue.channel().closeFuture().sync();

         } catch (Exception e) {
             // TODO: handle exception
         }
     }

     private class ChildChannelHandler extends ChannelInitializer<SocketChannel>{

         @Override
         protected void initChannel(SocketChannel ch) throws Exception {
             ch.pipeline().addLast(new SimpleServerHandler());
         }

     }
 }

 import java.util.Scanner;

 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;

 public class SimpleServerHandler extends ChannelInboundHandlerAdapter {

     @Override
     public void channelActive(ChannelHandlerContext ctx) throws Exception {

         ChannelManager.serverChannel = ctx;

         new Thread(new Runnable() {

             @Override
             public void run() {
                 // TODO Auto-generated method stub
                 while(true){

                     Scanner sc = new Scanner(System.in);
                     byte [] req = sc.nextLine().getBytes();
                     ByteBuf msg = Unpooled.buffer(req.length);
                     msg.writeBytes(req);
                     ChannelManager.serverChannel.writeAndFlush(msg);
                 }
             }
         }).start();
     }

     @Override
     public void channelRead(ChannelHandlerContext ctx, Object msg)
             throws Exception {
         ByteBuf buf = (ByteBuf) msg;
         byte [] req = new byte[buf.readableBytes()];

         buf.readBytes(req);
         String message = new String(req,"UTF-8");
         System.out.println("server:"+message);
     }

 }

　　上述两个类实现netty的服务端，下面就是客户端啦

 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;

 public class NettyClient {

     public static void main(String[] args) {
         new NettyClient().connect(8989, "127.0.0.1");
     }

     public void connect(int port, String host){
         EventLoopGroup  group = new NioEventLoopGroup();

         try {
             Bootstrap bootstrap = new Bootstrap();
             bootstrap.group(group)
             .channel(NioSocketChannel.class)
             .option(ChannelOption.TCP_NODELAY, true)
             .handler(new ChannelInitializer<SocketChannel>() {

                 @Override
                 protected void initChannel(SocketChannel ch) throws Exception {
                     // TODO Auto-generated method stub
                     ch.pipeline().addLast(new SimpleClientHandler());
                 }

             });
             ChannelFuture channelFuture = bootstrap.connect(host,port).sync();
             channelFuture.channel().closeFuture().sync();

         } catch (Exception e) {
             // TODO: handle exception
         }
     }
 }

 import java.util.Scanner;

 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;

 public class SimpleClientHandler extends ChannelInboundHandlerAdapter {

     private ByteBuf clientMessage;

     public SimpleClientHandler(){
         byte [] req = "call-user-service".getBytes();
         clientMessage = Unpooled.buffer(req.length);
         clientMessage.writeBytes(req);
     }

     @Override
     public void channelActive(ChannelHandlerContext ctx) throws Exception {

         ChannelManager.clientChannel = ctx;

         new Thread(new Runnable() {

             @Override
             public void run() {
                 // TODO Auto-generated method stub
                 while(true){

                     Scanner sc = new Scanner(System.in);
                     byte [] req = sc.nextLine().getBytes();
                     ByteBuf msg = Unpooled.buffer(req.length);
                     msg.writeBytes(req);
                     ChannelManager.clientChannel.writeAndFlush(msg);
                 }
             }
         }).start();
     }

     @Override
     public void channelRead(ChannelHandlerContext ctx, Object msg)
             throws Exception {
         ByteBuf buf = (ByteBuf) msg;
         byte [] req = new byte[buf.readableBytes()];
         buf.readBytes(req);

         String message = new String(req,"UTF-8");
         System.out.println("client:"+message);
     }

     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
             throws Exception {
         ctx.close();
     }

 }

　　好了，万事俱备，再添加一个ChannelManager.java netty的通道管理器

 import io.netty.channel.ChannelHandlerContext;

 public class ChannelManager {

     public static ChannelHandlerContext serverChannel;
     public static ChannelHandlerContext clientChannel;
 }

这样就可以实现netty的前后端的控制台通讯了，代码解释就不进行了