netty实现udp服务端和客户端

https://netty.io/wiki/

1、pom文件

     
            io.netty
            netty-all
            4.1.75.Final
        

2、服务端实现  UdpServerHandler

package com.example.demo.udp;

import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.socket.DatagramPacket;
import io.netty.util.CharsetUtil;


public class UdpServerHandler extends SimpleChannelInboundHandler {


    @Override
    public void channelRead0(ChannelHandlerContext ctx, DatagramPacket packet) throws Exception {
        String msg = packet.content().toString(CharsetUtil.UTF_8);
        System.err.println("服务端接收消息:" + msg);
        if (msg.startsWith("1")) {
            ctx.write(new DatagramPacket(
                    Unpooled.copiedBuffer("QOTM:111111", CharsetUtil.UTF_8), packet.sender()));
        } else {
            ctx.write(new DatagramPacket(
                    Unpooled.copiedBuffer("QOTM:2222222222", CharsetUtil.UTF_8), packet.sender()));
        }

    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.flush();
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        // We don't close the channel because we can keep serving requests.
    }
}

UdpServer

package com.example.demo.udp;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioDatagramChannel;

/**
 * A UDP server that responds to the QOTM (quote of the moment) request to a {@link UdpClient}.
 * 

 * Inspired by the official
 * Java tutorial.
 */
public final class UdpServer {

    private static final int PORT = Integer.parseInt(System.getProperty("port", "7686"));

    public static void main(String[] args) throws Exception {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group)
                    .channel(NioDatagramChannel.class)
                    .option(ChannelOption.SO_BROADCAST, true)
                    .handler(new UdpServerHandler());

            b.bind(PORT).sync().channel().closeFuture().await();
        } finally {
            group.shutdownGracefully();
        }
    }
}

3、客户端实现  

UdpClientHandler

package com.example.demo.udp;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.socket.DatagramPacket;
import io.netty.util.CharsetUtil;

public class UdpClientHandler extends SimpleChannelInboundHandler {

    @Override
    public void channelRead0(ChannelHandlerContext ctx, DatagramPacket msg) throws Exception {
        String response = msg.content().toString(CharsetUtil.UTF_8);
        System.err.println("客户端接收到消息:" + response);
    }

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

UdpClient

package com.example.demo.udp;

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.DatagramPacket;
import io.netty.channel.socket.nio.NioDatagramChannel;
import io.netty.util.CharsetUtil;
import io.netty.util.internal.SocketUtils;

/**
 * A UDP broadcast client that asks for a quote of the moment (QOTM) to {@link UdpServer}.
 * 

 * Inspired by the official
 * Java tutorial.
 */
public final class UdpClient {

    static final int PORT = Integer.parseInt(System.getProperty("port", "7686"));

    public static void main(String[] args) throws Exception {

        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group)
                    .channel(NioDatagramChannel.class)
                    .option(ChannelOption.SO_BROADCAST, true)
                    .handler(new UdpClientHandler());

            Channel ch = b.bind(0).sync().channel();

            // Broadcast the QOTM request to port 8080.
            ch.writeAndFlush(new DatagramPacket(
                    Unpooled.copiedBuffer("4444444", CharsetUtil.UTF_8),
                    SocketUtils.socketAddress("255.255.255.255", PORT))).sync();
            ch.closeFuture().await();
        } finally {
            group.shutdownGracefully();
        }
    }
}