《Netty权威指南》（一）简单的时间服务器P69

由于该书是基于Netty5编写的样例代码，而Netty5已经被官方废弃。

目前基于推荐版的4.1.12.Final在学习过程中，可能会出现个别接口不一致的情况。所以记录可在4.1.12下编译通过的代码

package net.xjdsz.n;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import java.util.Date;
/**
 * Created by dingshuo on 2017/6/14.
 */
public class TimeServer {
    public void bind(int port) throws Exception{
        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 ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            socketChannel.pipeline().addLast(new 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("收到数据:"+body);
                                    String currentTime=new Date(System.currentTimeMillis()).toString();
                                    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();
                                }
                            });
                        }
                    });
            //绑定端口，同步等待成功
            ChannelFuture f=b.bind(port).sync();
            //等待服务端监听端口关闭
            f.channel().closeFuture().sync();
        }finally {
            //退出，释放资源
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
    public static void main(String[] args) throws Exception{
        TimeServer timeServer=new TimeServer();
        timeServer.bind(2000);
    }
}