Netty入门

涉及的java类
TimerServer
TimerServerHandler
TimerClient
TimerClientHandler

pxm.xml

  <dependency>
      <groupId>io.netty</groupId>
      <artifactId>netty-all</artifactId>
      <version>4.1.6.Final</version>
    </dependency>

TimerServer

package com.itcast.io.netty;

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;

/**
 * Created by Administrator on 2019/6/23.
 */
public class TimerServer {
    public void bind(int port) throws Exception {
        //配置服务端的线程组，两个线程组，一个用于服务端接收客户端连接，另一个进行SocketChannel的网络读写
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            //ServerBootstrap用于启动NIO服务端的辅助启动类，目的是降低服务端开发复杂度
            ServerBootstrap bootstrap = new ServerBootstrap();
            bootstrap.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 1024)
                    .childHandler(new ChildChannelHandler());
            //绑定端口，同步等待成功
            ChannelFuture future=bootstrap.bind(port).sync();

            //等待服务端监听端口关闭
            future.channel().closeFuture().sync();
        }finally {
            //优雅退出，释放线程资源
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }

    private class ChildChannelHandler extends ChannelInitializer<SocketChannel> {

        protected void initChannel(SocketChannel socketChannel) throws Exception {
            socketChannel.pipeline().addLast(new TimerServerHandler());
        }
    }

    public static void main(String[] args)throws Exception{
        int port=8081;
        if(args!=null&&args.length>0){
            try {
                port=Integer.valueOf(args[0]);
            }catch (NumberFormatException e){

            }
        }
        new TimerServer().bind(port);
    }

}

TimerServerHandler

package com.itcast.io.netty;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.*;

import java.sql.Date;


/**
 * Created by Administrator on 2019/6/23.
 */
class TimerServerHandler extends ChannelInboundHandlerAdapter  {

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
            throws Exception {
        ctx.close();
    }
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        //ByteBuf类似于JDK中的java.nio.ByteBuffer对象，不过它提供了更加强大和灵活的功能。
        ByteBuf buf=(ByteBuf) msg;
        byte[] req=new byte[buf.readableBytes()];
        buf.readBytes(req);
        String body=new String(req, "UTF-8");
        System.out.println("The time server receive order : "+body);
        String currentTime="QUERY TIME ORDER".equalsIgnoreCase(body) ? new
                Date(System.currentTimeMillis()).toString() : "BAD ORDER";
        ByteBuf resp=Unpooled.copiedBuffer(currentTime.getBytes());
        ctx.write(resp);
    }

    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        ctx.flush();
    }
}

TimerClient

package com.itcast.io.netty;

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;

/**
 * Created by Administrator on 2019/6/23.
 */
public class TimerClient {
    public void connect(String host, int port) throws Exception {
        //配置客户端NIO线程组
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(group).channel(NioSocketChannel.class)
                    .option(ChannelOption.TCP_NODELAY, true)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            socketChannel.pipeline().addLast(new TimerClientHandler());
                        }
                    });
            //发起异步连接操作，同步等待连接成功
            ChannelFuture future=bootstrap.connect(host,port).sync();

            //等待客户端链路关闭
            future.channel().closeFuture().sync();
        }finally {
            //优雅退出，释放NIO线程组
            group.shutdownGracefully();
        }
    }

    public static void main(String[] args)throws Exception{
        int port=8081;
        if(args!=null&&args.length>0){
            try {
                port=Integer.valueOf(port);
            }catch (NumberFormatException e){

            }
        }
        new TimerClient().connect("127.0.0.1",port);
    }

}

TimerClientHandler

package com.itcast.io.netty;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.*;

import java.util.logging.Logger;

/**
 * Created by Administrator on 2019/6/23.
 */
public class TimerClientHandler extends ChannelInboundHandlerAdapter  {

    private static final Logger logger = Logger.getLogger(TimerClientHandler.class.getName());

    private final ByteBuf firstMessage;

    public TimerClientHandler() {
        byte[] request = "QUERY TIME ORDER".getBytes();
        firstMessage = Unpooled.buffer(request.length);
        firstMessage.writeBytes(request);
    }

    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        logger.warning("Unexpected exception from downstream : "+cause.getMessage());
        ctx.close();
    }

    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("client channelActive" + firstMessage);
        ctx.writeAndFlush(firstMessage);
    }

    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("Now is :"+body);
    }
}