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1、发送数据报

(1)创建DatagramSocket并连接

DatagramSocket client = new DatagramSocket();
InetAddress addr = InetAddress.getByName(reqHost);
int port = Integer.valueOf(reqPort);
client.connect(addr, port);

(2)构造数据报

(3)发送数据

client.send(sendPacket);

(4)关闭连接

2、接受数据

(1)创建指定监听端口的socket服务

DatagramSocket server = new DatagramSocket(10001);

(2)构建接受数据报容器

 byte[] buf = new byte[1024];//接受内容的大小，注意不要溢出  
    DatagramPacket dp = new DatagramPacket(buf,0,buf.length);//定义一个接收的包  </pre>

(3)接受
server.receive(recvPacket);


(4)关闭资源
3、示例代码
public class UdpSentUtil {
	private static DatagramSocket client;
	private static String reqHost = DOGlobals.getValue("cws.host");
	private static String reqPort = DOGlobals.getValue("cws.port");
	private static RecMsg recThead;
	private static UdpSentUtil self = new UdpSentUtil();
	public static ExecutorService fixedThreadPool = Executors.newFixedThreadPool(10); 
private UdpSentUtil(){
		try {
			client = new DatagramSocket();
			InetAddress addr = InetAddress.getByName(reqHost);
			int port = Integer.valueOf(reqPort);
			client.connect(addr, port);
		recThead = new RecMsg(client);
		recThead.start();
		System.out.println("=========="+recThead.getName());
		//reciveMsg();
	} catch (SocketException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
		client = null;
	} catch (UnknownHostException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
		client = null;
	}
}

public static UdpSentUtil getInstance(){

if(self != null && client != null && client.isConnected()){

return self;

}else{

self = new UdpSentUtil();

return self;

}

}

public void sendNoRecive(byte[] sendBuf){

DatagramPacket sendPacket = new DatagramPacket(sendBuf ,sendBuf.length);

if(client != null){

try {

if(!client.isConnected()){

InetAddress addr = InetAddress.getByName(reqHost);

int port = Integer.valueOf(reqPort);

client.connect(addr, port);

}

client.send(sendPacket);

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}

class RecMsg extends Thread{

private DatagramSocket client;

private String sign;
	public RecMsg(DatagramSocket client){
		this.client = client;
		this.sign = "";
	}
	public RecMsg(DatagramSocket client,String sign){
		this.client = client;
		this.sign = sign;
	}
	
	public void run() {
		// TODO Auto-generated method stub
		byte[] recvBuf = new byte[1024*4];
        DatagramPacket recvPacket
            = new DatagramPacket(recvBuf , recvBuf.length);
        String recvStr = "";
		try {
        	while(client != null){
        		System.out.println(this.sign+"等待接受。。。。。。");
        		client.receive(recvPacket);
        		recvStr = new String(recvPacket.getData() , 0 ,recvPacket.getLength(),"UTF-8");
        		System.out.println(this.sign+"收到信息："+recvStr);
        		fixedThreadPool.execute(new ParseMsg(recvStr));
        	}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
}

/**
 * 解析信息
 * @author user
 *
 */
class ParseMsg extends Thread{
	private String msg;
	public ParseMsg(String msg){
		this.msg = msg;
	}
	
	public void run() {
		//解析xml数据
	}
	
	private void dealMsg(Document doc,String cid){
		//处理相应数据
	}
	
	private Map respToMap(List&lt;Element&gt; lrs){
		Map&lt;String,String&gt; m = new HashMap&lt;String, String&gt;();
		if(lrs != null){
			for (int i = 0; i &lt; lrs.size(); i++) {
				m.put(lrs.get(i).getName(), lrs.get(i).getText());
			}
		}
		return m;
	}
	
	public List respToList(List&lt;Element&gt; lrs){
		List&lt;Map&gt; lms = new ArrayList&lt;Map&gt;();
		if(lrs != null){
			for (int i = 0; i &lt; lrs.size(); i++) {
				lms.add(respToMap((List&lt;Element&gt;) lrs.get(i).selectNodes("./*")));
			}
		}
		return lms;
	}
}

}