简单实现 -UDP通信（xml解析）学习笔记：

简单实现发送和接收：

1.主函数：

package udp_01;

public class ChatMain {
	public static void main(String[] args) {
		ChatReceive chatReceive = new ChatReceive();
		chatReceive.start();
		ChatSender chatSender = new ChatSender();
		chatSender.start();
	}
}

2.发送端：

package udp_01;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.xml.sax.SAXException;

/*
* 发送端
*/
public class ChatSender extends Thread {
	@Override
	public void run() {
		try {
			//解析xml
			DocumentBuilderFactory builderFactory= DocumentBuilderFactory.newInstance();
			DocumentBuilder builder = builderFactory.newDocumentBuilder();
			Document document = builder.parse("src/udp.xml");
			String ip = document.getElementsByTagName("ip").item(0).getTextContent();
			String port = document.getElementsByTagName("port").item(0).getTextContent();
		
			byte[] hwa={'@','@','$','$','#','#','*','*'};
			int cmdId = 2222;  
		    int dataSize = 3333;  
		    char ciaFilePath[] = {'测','试'};
		
			String infor = new SocketPacket().getString(hwa,cmdId,dataSize,ciaFilePath);
			//建立UDP服务
			DatagramSocket socket = new DatagramSocket();
			// 准备数据，把数据封装到数据包中	
			byte data[] = infor.getBytes();
			DatagramPacket packet = null;
			packet = new DatagramPacket(data, data.length, InetAddress.getByName(ip), Integer.parseInt(port));
			// 发送数据
			socket.send(packet);
			// 关闭资源
			socket.close();
		} catch(IOException e) {
			e.printStackTrace();
		} catch (ParserConfigurationException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SAXException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

}

3.接收端：

package udp_01;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.xml.sax.SAXException;

/**
* 接收端
*/
public class ChatReceive extends Thread{
	@Override
	public void run() {
		try {
			//解析xml
			DocumentBuilderFactory builderFactory= DocumentBuilderFactory.newInstance();
			DocumentBuilder builder = builderFactory.newDocumentBuilder();
			Document document = builder.parse("src/udp.xml");
			String port = document.getElementsByTagName("port").item(0).getTextContent();
			
			// 创建UDP的服务
			DatagramSocket socket = new DatagramSocket(Integer.parseInt(port));
			// 准备空的数据包存储数据
			byte[] buf = new byte[1024];
			DatagramPacket packet = new DatagramPacket(buf, buf.length);
			boolean flag = true;
			while(flag) {
				socket.receive(packet);
				// packet.getAddress() 获取对方数据包的IP地址对象
				//System.out.println(packet.getAddress().getHostAddress() + "传送：" + new String(buf, 0 ,packet.getLength()));
				System.out.println("Header: " + new String(buf, 0 ,8 ));
				System.out.println("Data: " + new String(buf, 8 ,packet.getLength()));
			}
			// 关闭资源
			socket.close();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (ParserConfigurationException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SAXException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

4.工具类：

package udp_01;

public class SocketPacket {  
	  
    private byte hwa;
    private int cmdId;  
    private int dataSize;  
    private char ciaFilePath;  
    
    public SocketPacket() {}

    public SocketPacket(byte hwa, int cmdId, int dataSize, char ciaFilePath) {
		super();
		this.hwa = hwa;
		this.cmdId = cmdId;
		this.dataSize = dataSize;
		this.ciaFilePath = ciaFilePath;
	}

	public byte getHwa() {
		return hwa;
	}

	public void setHwa(byte hwa) {
		this.hwa = hwa;
	}

	public int getCmdId() {
		return cmdId;
	}

	public void setCmdId(int cmdId) {
		this.cmdId = cmdId;
	}

	public int getDataSize() {
		return dataSize;
	}

	public void setDataSize(int dataSize) {
		this.dataSize = dataSize;
	}

	public char getCiaFilePath() {
		return ciaFilePath;
	}

	public void setCiaFilePath(char ciaFilePath) {
		this.ciaFilePath = ciaFilePath;
	}

    //字节装转报文string  
    public String getString(byte[] hwa, int cmdId, int dataSize, char[] ciaFilePath){       
    	String s_hwa = new String(hwa);
    	String s_cmdId = String.valueOf(cmdId);
        String s_dataSize = String.valueOf(dataSize);
        String s_ciaFilePath = new String(ciaFilePath);
        return s_hwa+s_cmdId+s_dataSize+s_ciaFilePath;  
    }  
      
}  

5.xml解析：

<?xml version="1.0" encoding="UTF-8"?>
<address category="udp">
<ip>127.0.0.1</ip>
<port>9902</port>
</address>

测试结果：