netty入门实例

《Netty 5用户指南》http://ifeve.com/netty5-user-guide/

Netty是一个NIO框架，使用它可以简单快速地开发网络应用程序，比如客户端和服务端的协议。

Netty大大简化了网络程序的开发过程比如TCP和UDP的 Socket的开发。

1、Client.java

 1 package com.yxq.test;
 2 import io.netty.bootstrap.Bootstrap;
 3 import io.netty.buffer.Unpooled;
 4 import io.netty.channel.ChannelFuture;
 5 import io.netty.channel.ChannelInitializer;
 6 import io.netty.channel.EventLoopGroup;
 7 import io.netty.channel.nio.NioEventLoopGroup;
 8 import io.netty.channel.socket.SocketChannel;
 9 import io.netty.channel.socket.nio.NioSocketChannel;
10 
11 public class Client {
12 
13     public static void main(String[] args) throws Exception {
14 
15         EventLoopGroup workgroup = new NioEventLoopGroup();
16         Bootstrap b = new Bootstrap();
17         b.group(workgroup)
18                 .channel(NioSocketChannel.class)
19                 .handler(new ChannelInitializer<SocketChannel>() {
20                     @Override
21                     protected void initChannel(SocketChannel sc) throws Exception {
22                         sc.pipeline().addLast(new ClientHandler());
23                     }
24                 });
25 
26         ChannelFuture cf1 = b.connect("127.0.0.1", 8765).sync();
27 
28         //buf
29         cf1.channel().writeAndFlush(Unpooled.copiedBuffer("777".getBytes()));
30 
31         cf1.channel().closeFuture().sync();
32         workgroup.shutdownGracefully();
33 
34     }
35 }

2、ClientHandler.java

 1 package com.yxq.test;
 2 
 3 import io.netty.buffer.ByteBuf;
 4 import io.netty.buffer.Unpooled;
 5 import io.netty.channel.ChannelHandlerAdapter;
 6 import io.netty.channel.ChannelHandlerContext;
 7 import io.netty.util.ReferenceCountUtil;
 8 
 9 public class ClientHandler extends ChannelHandlerAdapter {
10 
11     @Override
12     public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
13         try {
14             //do something msg
15             ByteBuf buf = (ByteBuf)msg;
16             byte[] data = new byte[buf.readableBytes()];
17             buf.readBytes(data);
18             String request = new String(data, "utf-8");
19             System.out.println("Client: " + request);
20 
21 
22         } finally {
23             ReferenceCountUtil.release(msg);
24         }
25     }
26 
27     @Override
28     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
29         cause.printStackTrace();
30         ctx.close();
31     }
32 }

3、Server.java

 1 package com.yxq.test;
 2 import io.netty.bootstrap.ServerBootstrap;
 3 import io.netty.channel.ChannelFuture;
 4 import io.netty.channel.ChannelInitializer;
 5 import io.netty.channel.ChannelOption;
 6 import io.netty.channel.EventLoopGroup;
 7 import io.netty.channel.nio.NioEventLoopGroup;
 8 import io.netty.channel.socket.SocketChannel;
 9 import io.netty.channel.socket.nio.NioServerSocketChannel;
10 
11 public class Server {
12 
13     public static void main(String[] args) throws Exception {
14         //1 第一个线程组 是用于接收Client端连接的
15         EventLoopGroup bossGroup = new NioEventLoopGroup();
16         //2 第二个线程组 是用于实际的业务处理操作的
17         EventLoopGroup workerGroup = new NioEventLoopGroup();
18 
19         //3 创建一个辅助类Bootstrap，就是对我们的Server进行一系列的配置
20         ServerBootstrap b = new ServerBootstrap();
21         //把俩个工作线程组加入进来
22         b.group(bossGroup, workerGroup)
23                 //我要指定使用NioServerSocketChannel这种类型的通道
24                 .channel(NioServerSocketChannel.class)
25                 //一定要使用 childHandler 去绑定具体的 事件处理器
26                 .childHandler(new ChannelInitializer<SocketChannel>() {
27                     @Override
28                     protected void initChannel(SocketChannel sc) throws Exception {
29                         sc.pipeline().addLast(new ServerHandler());
30                     }
31                 });
32 
33         //绑定指定的端口 进行监听
34         ChannelFuture f = b.bind(8765).sync();
35 
36         //Thread.sleep(1000000);
37         f.channel().closeFuture().sync();
38 
39         bossGroup.shutdownGracefully();
40         workerGroup.shutdownGracefully();
41 
42 
43 
44     }
45 
46 }

4、ServerHandler.java

 1 package com.yxq.test;
 2 
 3 import io.netty.buffer.ByteBuf;
 4 import io.netty.buffer.Unpooled;
 5 import io.netty.channel.ChannelFuture;
 6 import io.netty.channel.ChannelFutureListener;
 7 import io.netty.channel.ChannelHandlerAdapter;
 8 import io.netty.channel.ChannelHandlerContext;
 9 import io.netty.util.ReferenceCountUtil;
10 
11 public class ServerHandler  extends ChannelHandlerAdapter {
12 
13     @Override
14     public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
15 
16         //do something msg
17         ByteBuf buf = (ByteBuf)msg;
18         byte[] data = new byte[buf.readableBytes()];
19         buf.readBytes(data);
20         String request = new String(data, "utf-8");
21         System.out.println("Server: " + request);
22         //写给客户端
23         String response = "我是反馈的信息";
24         ctx.writeAndFlush(Unpooled.copiedBuffer("888".getBytes()));
25         //.addListener(ChannelFutureListener.CLOSE);
26 
27 
28     }
29 
30     @Override
31     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
32         cause.printStackTrace();
33         ctx.close();
34     }
35 
36 }

打印：

先启server端，再启client端