netty学习demo01

最近一直在学习netty，吧自己学的时敲的代码和犯错的地方分析，希望能帮助到和我一样的新手

以时间请求通信为例（这也是netty权威指南的上的java代码）

分享一下我简单粗暴的学习方法，不懂的代码先敲3遍以上，在去看书会比直接看书效果好。

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;public class TimeServer {public void bind(int port) throws Exception {EventLoopGroup bossgroup = new NioEventLoopGroup();EventLoopGroup workgroup = new NioEventLoopGroup();try {ServerBootstrap b = new ServerBootstrap();b.group(bossgroup,workgroup).channel(NioServerSocketChannel.class)    .option(ChannelOption.SO_BACKLOG, 1024)    .childHandler(new ChildChannelHandler());ChannelFuture f = b.bind(port).sync();f.channel().closeFuture().sync();//这个地方我是过一次直接关闭（f.channel().close（）），导致的问题是客户端启动后发送完消息直接就关闭了} finally {bossgroup.shutdownGracefully();workgroup.shutdownGracefully();}}private class ChildChannelHandler extends ChannelInitializer<SocketChannel>{@Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new TimeServerHandler());}}public static void main(String[] args) throws Exception {int port =8080;try {if(args!=null && args.length>0) {port = Integer.valueOf(args[0]);}} catch (Exception e) {// TODO: handle exception}new TimeServer().bind(port);}}

服务器的TimeServerHandler方法需要继承ChannelHandlerAdapter

import io.netty.buffer.ByteBuf;import io.netty.buffer.Unpooled;import io.netty.channel.ChannelHandlerAdapter;import io.netty.channel.ChannelHandlerContext;public class TimeServerHandler extends ChannelHandlerAdapter {@Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {ByteBuf buf = (ByteBuf) msg;byte[] rep = new byte[buf.readableBytes()];buf.readBytes(rep);String body = new String(rep,"utf-8");System.out.println("The time server receive order : "+body);String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body) ? new java.util.Date(System.currentTimeMillis()).toString() : "BAD ORDER";ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes());ctx.write(resp);}@Overridepublic void channelReadComplete(ChannelHandlerContext ctx) throws Exception {ctx.flush();}@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {ctx.close();}}

客户端

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 TimeClient {public void connect(int port,String host) throws Exception {EventLoopGroup group = new NioEventLoopGroup();try {Bootstrap b = new Bootstrap();b.group(group).channel(NioSocketChannel.class)  .option(ChannelOption.TCP_NODELAY, true)  .handler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel arg0) throws Exception {arg0.pipeline().addLast(new TimeClientHandler());}});ChannelFuture f = b.connect(host,port).sync();f.channel().closeFuture().sync();} finally {group.shutdownGracefully();}}public static void main(String[] args) throws Exception {int port=8080;try {if (args!=null && args.length>0) {port = Integer.valueOf(args[0]);}} catch (Exception e) {}new TimeClient().connect(port, "127.0.0.1");}}

客户端的TimeClientHandler

import java.util.logging.Logger;import com.phei.netty.nio.TimeClientHandle;import io.netty.buffer.ByteBuf;import io.netty.buffer.Unpooled;import io.netty.channel.ChannelHandlerAdapter;import io.netty.channel.ChannelHandlerContext;public class TimeClientHandler extends ChannelHandlerAdapter {private static final Logger logger = Logger.getLogger(TimeClientHandle.class.getName());private final ByteBuf firstMessage;public TimeClientHandler() {byte[] req = "QUERY TIME ORDER".getBytes();firstMessage = Unpooled.buffer(req.length);firstMessage.writeBytes(req);}@Overridepublic 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("Now is"+body);}@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {ctx.writeAndFlush(firstMessage);}@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause){logger.warning("Unexpected exception from downstream : "+ cause.getMessage());ctx.close();}}