Java UDP Socket编程

 1 import java.io.IOException;
 2 import java.io.InterruptedIOException;
 3 import java.net.DatagramPacket;
 4 import java.net.DatagramSocket;
 5 import java.net.InetAddress;
 6 
 7 public class UdpClient {
 8     private static final int MAXNUM = 5; // 设置重发数据的最多次数
 9     private static final int TIMEOUT = 5000;  //设置接收数据的超时时间
10     private static final int CLIENT_PORT = 2222;
11     private static final int SERVER_PORT = 3222;
12     private static final int REV_SIZE = 1024; //接收数据的存储空间大小
13     
14     public static void main(String[] args) throws IOException {
15         String str_send = "Hello UDPserver"; //要发送的字串
16         byte[] buf_rev = new byte[REV_SIZE];     //要接收的存储空间
17         
18         /*第一步 实例化DatagramSocket*/
19         DatagramSocket mSoc = new DatagramSocket(CLIENT_PORT);
20         mSoc.setSoTimeout(TIMEOUT);              //设置接收数据时阻塞的最长时间  
21         
22         /*第二步 实例化用于发送的DatagramPacket和用于接收的DatagramPacket*/
23         InetAddress inetAddress = InetAddress.getLocalHost();
24         DatagramPacket data_send = new DatagramPacket(str_send.getBytes(),
25                 str_send.length(), inetAddress, SERVER_PORT);
26         
27         DatagramPacket data_rev = new DatagramPacket(buf_rev, REV_SIZE);
28 
29         
30         /*第三步 DatagramPacket send发送数据，receive接收数据*/
31         int send_count = 0; // 重发数据的次数
32         boolean revResponse = false; // 是否接收到数据的标志位
33         while (!revResponse && send_count < MAXNUM) {
34             try {
35                 mSoc.send(data_send); //发送数据
36                 mSoc.receive(data_rev);//接收数据
37                 if (!data_rev.getAddress().getHostAddress()
38                         .equals(InetAddress.getLocalHost().getHostAddress())) {
39                     throw new IOException(
40                             "Received packet from an umknown source");
41                 }
42                 revResponse = true;
43             } catch (InterruptedIOException e) {
44                 // 如果接收数据时阻塞超时，重发并减少一次重发的次数
45                 send_count += 1;
46                 System.out.println("Time out," + (MAXNUM - send_count)
47                         + " more tries...");
48             }
49         }
50         if (revResponse) {
51             // 如果收到数据，则打印出来
52             System.out.println("client received data from server：");
53             String str_receive = new String(data_rev.getData(), 0,
54                     data_rev.getLength())
55                     + " from "
56                     + data_rev.getAddress().getHostAddress()
57                     + ":"
58                     + data_rev.getPort();
59             System.out.println(str_receive);
60             // 由于dp_receive在接收了数据之后，其内部消息长度值会变为实际接收的消息的字节数，
61             // 所以这里要将dp_receive的内部消息长度重新置为1024
62             data_rev.setLength(REV_SIZE);
63         } else {
64             // 如果重发MAXNUM次数据后，仍未获得服务器发送回来的数据，则打印如下信息
65             System.out.println("No response -- give up.");
66         }
67         
68         /*第四步 关闭DatagramPacket*/
69         mSoc.close();
70     }
71 
72 }

 1 import java.io.IOException;
 2 import java.net.DatagramPacket;
 3 import java.net.DatagramSocket;
 4 import java.net.InetAddress;
 5 
 6 public class UdpServer {
 7 
 8     private static final int SERVER_PORT = 3222;
 9     private static final int REV_SIZE = 1024; // 接收数据的存储空间大小
10 
11     public static void main(String[] args) throws IOException {
12         byte[] buf_rev = new byte[REV_SIZE];
13         String str_send = "Hello UDPclient";
14         /* 第一步 实例化DatagramSocket */
15         DatagramSocket mSoc = new DatagramSocket(SERVER_PORT);
16 
17         /* 第二步 实例化用于接收的DatagramPacket 并从DatagramSocket接收数据 */
18         DatagramPacket data_rev = new DatagramPacket(buf_rev, REV_SIZE);
19         boolean f = true;
20         while (f) {
21             mSoc.receive(data_rev);
22             InetAddress inetAddress = data_rev.getAddress();
23             int port = data_rev.getPort();
24             System.out.println("server received data from client：");
25             String str_rev = new String(data_rev.getData(), 0,
26                     data_rev.getLength())
27                     + " from " + inetAddress.getHostAddress() + ":" + port;
28             System.out.println(str_rev);
29 
30             /* 第三步 实例化用于发送的DatagramPacket，并从DatagramSocket中发送出去 */
31             DatagramPacket data_send = new DatagramPacket(str_send.getBytes(),
32                     str_send.length(), inetAddress, port);
33             mSoc.send(data_send);
34 
35             /*
36              * 由于dp_receive在接收了数据之后，其内部消息长度值会变为实际接收的消息的字节数，
37              * 所以这里要将dp_receive的内部消息长度重新置为1024
38              */
39             data_rev.setLength(REV_SIZE);
40         }
41         mSoc.close();
42 
43     }
44 }