netty 3.9.2 UDP协议服务器和客户端DEMO

说明：基于netty 3.9.2的udp协议实现的（如果你使用的版本是4.X或5.X，请参考其他方法）；程序的逻辑结构是，客户端发送给服务端一串数据，服务器端返回给客户端“A”。在进行游戏开发时需要对udp的丢包进行处理，可以利用服务器端的返回值进行相关处理，以确定是否重发，这方面具体没有实现。

文章结构：

一、服务器端

1、UDPServer

2、UdpChannelPipelineFactory

3、UDPServerHandler

二、客户端

1、UDPClient

2、UDPClientChannelPipelineFactory

3、UDPClientHandler

三、ScanGetPort获取一个可用的端口号

一、服务器端

1、UDPServer

初始化一个ConnectionlessBootstrap，setPipelineFactory，绑定一个端口号。ScanGetPort是一个工具类就是，获取一个可用的端口号，源代码在最后面贴出。

package com.ls.udp.server;

import java.net.InetSocketAddress;
import java.util.concurrent.Executors;

import org.jboss.netty.bootstrap.ConnectionlessBootstrap;
import org.jboss.netty.channel.socket.nio.NioDatagramChannelFactory;

import com.andy.server.util.ScanGetPort;

public class UDPServer {

    public final int PORT;
    public UDPServer(int port){
        PORT=port;
    }
    private ConnectionlessBootstrap  bootstrap;
    void start(){
        //init the bootstrap
        bootstrap=new ConnectionlessBootstrap(new NioDatagramChannelFactory(Executors.newCachedThreadPool()));
        bootstrap.setPipelineFactory(new UdpChannelPipelineFactory());
        bootstrap.bind(new InetSocketAddress(PORT));
        System.out.println("server start at:"+":"+PORT);
    }

    public static void main(String[] args) {
        /*
         * 获取一个可用的端口号
         */
        int port= new ScanGetPort().getPot(8080);
        new UDPServer(port).start();
    }

}

2、UdpChannelPipelineFactory

注册一个handler

package com.ls.udp.server;

import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.Channels;

public class UdpChannelPipelineFactory implements ChannelPipelineFactory{

    /**
     * set the channel pipeline
     *
     */
    @Override
    public ChannelPipeline getPipeline() throws Exception {
        ChannelPipeline pipeline = Channels.pipeline();
        pipeline.addLast("handler", new UDPServerHandler());
        return pipeline;
    }
}

3、UDPServerHandler

handler类

package com.ls.udp.server;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.DynamicChannelBuffer;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelUpstreamHandler;

public class UDPServerHandler extends SimpleChannelUpstreamHandler{

    /**
     *  对于ChannelHandler，
     *  是UDP与TCP区别的核心所在。
     *  大家都知道UDP是无连接的，
     *  也就是说你通过 MessageEvent 参数对象的 getChannel() 方法获取当前会话连接，
     *  但是其 isConnected() 永远都返回 false。
     *  UDP 开发中在消息获取事件回调方法中，
     *  获取了当前会话连接 channel 对象后可直接通过 channel 的 write 方法发送数据给对端 channel.write(message, remoteAddress)，
     *  第一个参数仍然是要发送的消息对象，
     *  第二个参数则是要发送的对端 SocketAddress 地址对象。
     *  这里最需要注意的一点是SocketAddress，在TCP通信中我们可以通过channel.getRemoteAddress()获得，
     *  但在UDP通信中，我们必须从MessageEvent中通过调用getRemoteAddress()方法获得对端的SocketAddress 地址。
     */
    @Override
    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e)
            throws Exception {

        ChannelBuffer buffer = (ChannelBuffer)e.getMessage();
        byte[] recByte=buffer.copy().toByteBuffer().array();

        String msg=new String(recByte);
        System.out.println("from client:"+msg);

        ChannelBuffer responseBuffer= new DynamicChannelBuffer(1);

        responseBuffer.writeBytes("A".getBytes());

        //write to the client
        e.getChannel().write(responseBuffer, e.getRemoteAddress());

        super.messageReceived(ctx, e);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e)
            throws Exception {
        super.exceptionCaught(ctx, e);
    }

}

二、客户端

（基本结构和服务器端很像，不再赘述）

1、UDPClient

package com.ls.udp.client;

import java.net.InetSocketAddress;
import java.util.Scanner;

import org.jboss.netty.bootstrap.ConnectionlessBootstrap;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.DynamicChannelBuffer;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.socket.nio.NioDatagramChannelFactory;

public class UDPClient {

    private ConnectionlessBootstrap  bootstrap;
    private Channel channel;
    public void start(){
        //init the bootstrap
        bootstrap=new ConnectionlessBootstrap(new NioDatagramChannelFactory());
        bootstrap.setPipelineFactory(new UDPClientChannelPipelineFactory());
        bootstrap.setOption("localAddress", new InetSocketAddress(10001));
        channel=bootstrap.bind();
    }

    public void writebytes(byte[] bt,InetSocketAddress isa){
        if(bootstrap==null){
            this.start();
        }
        ChannelBuffer responseBuffer= new DynamicChannelBuffer(12);

        responseBuffer.writeBytes(bt);
        channel.write(responseBuffer, isa);
    }

    public static void main(String[] args) {

        UDPClient uClient=new UDPClient();

        Scanner scanner=new Scanner(System.in);
        String lienString=scanner.nextLine();
        while(!lienString.equals("bye")){

            uClient.writebytes(lienString.getBytes(), new InetSocketAddress("192.168.1.107",8080));
            lienString=scanner.nextLine();
        }
    }

}

2、UDPClientChannelPipelineFactory

package com.ls.udp.client;

import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.Channels;
public class UDPClientChannelPipelineFactory implements ChannelPipelineFactory{

    /**
     * set the channel pipeline
     *
     */
    @Override
    public ChannelPipeline getPipeline() throws Exception {
        ChannelPipeline pipeline = Channels.pipeline();
        pipeline.addLast("handler", new UDPClientHandler());
        return pipeline;
    }
}

3、UDPClientHandler

package com.ls.udp.client;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelUpstreamHandler;

public class UDPClientHandler extends SimpleChannelUpstreamHandler{

    @Override
    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e)
            throws Exception {

        ChannelBuffer buffer = (ChannelBuffer)e.getMessage();
        byte[] recByte=buffer.copy().toByteBuffer().array();

        String msg=new String(recByte);
        System.out.println("from server:"+msg);

        super.messageReceived(ctx, e);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e)
            throws Exception {
        super.exceptionCaught(ctx, e);
    }

}

三、ScanGetPort获取一个可用的端口号

package com.andy.server.util;

import java.io.IOException;
import java.net.ServerSocket;
/**
 * get the port
 * @author red
 *
 */
public class ScanGetPort {
    public synchronized  int  getPot(int first){
        for(int i=first;i<65535;++i){
            ServerSocket ss=null;
            try {
                 ss= new ServerSocket(i);
            } catch (IOException e) {
                //e.printStackTrace();
            }finally{
                if(ss!=null){
                    if(ss.isBound()){
                        try {
                            ss.close();
                            System.out.println(i);
                            return i;
                        } catch (IOException e) {
                            e.printStackTrace();
                        }

                    }
                }
            }
        }
        return -1;
    }
}