Java基於UDP的多點廣播數據報技術的一個實現例子

This is a UDP network program. The following presents a multicast datagram program, which is actually a new technology.

[java]

1. package com.han;
2. import java.net.*;
3. /**
4. * This is a UDP network program.
5. * The following presents a multicast datagram program,
6. * which is actually a new technology.
7. *
8. * @author HAN
9. *
10. */
11. public class Weather extends Thread{
12. String weather ="節目預告： 八點有大型晚會，請收聽";
13. int port =9898;
14. InetAddress iaddress;//沒法初始化，這裡只能聲明。因為初始化new對象時要拋出異常所以在成員變量區域是語法通不過的。
15. MulticastSocket socket;
16. //在構造方法中初始化成員變量
17. Weather(){
18. try {
19. //A multicast group is specified by a class D IP address
20. //and by a standard UDP port number.
21. //Class D IP addresses are in the range 224.0.0.0 to 239.255.255.255, inclusive.
22. //The address 224.0.0.0 is reserved and should not be used.
23. iaddress=InetAddress.getByName("233.0.0.0");
24. socket=new MulticastSocket(port);
25. socket.setTimeToLive(1);
26. socket.joinGroup(iaddress);
27. }catch(Exception e){
28. e.printStackTrace();
29. }
31. }
32. @Override //最簡單的方法也就是建立一個線程來運行
33. public void run(){
34. while(true){
35. byte[] data=weather.getBytes();
36. DatagramPacket packet=new DatagramPacket(data,data.length,iaddress,port);
37. // System.out.println(weather);
38. System.out.println(new String(data));
39. try {
40. socket.send(packet);
41. sleep(3000);//線程休眠3秒
42. } catch (Exception e) {
43. // TODO Auto-generated catch block
44. e.printStackTrace();
45. }
46. }
47. }
48. public static void main(String[] args){
49. Weather w=new Weather();
50. w.start();
51. }
52. }

[java]

1. package com.han;
2. import java.awt.BorderLayout;
3. import java.awt.Color;
4. import java.awt.event.*;
5. import java.io.IOException;
6. import java.net.DatagramPacket;
7. import java.net.InetAddress;
8. import java.net.MulticastSocket;
9. import javax.swing.JButton;
10. import javax.swing.JFrame;
11. import javax.swing.JPanel;
12. import javax.swing.JScrollPane;
13. import javax.swing.JTextArea;
14. /**
15. * This is the receive part.
16. * @author HAN
17. *
18. */
19. public class Receive extends JFrame implements Runnable, ActionListener{
20. private static final long serialVersionUID = 3362377947503474102L;
21. int port=9898;
22. InetAddress group;
23. MulticastSocket socket; //socket sends and receives the packet.
24. DatagramPacket packet;
25. JButton ince=new JButton("開始接收");
26. JButton stop=new JButton("停止接收");
27. JTextArea inceAr=new JTextArea(10,20);
28. JTextArea inced=new JTextArea(10,20);
29. Thread thread;
30. boolean b = false;
31. byte[] buf=new byte[30];// If the message is longer than the packet's length, the message is truncated.
33. //在構造方法中設置具體參數特性，也就是初始化
34. public Receive(){
35. super("廣播數據報");
36. thread=new Thread(this);
37. ince.addActionListener(this);
38. stop.addActionListener(this);
39. inceAr.setForeground(Color.blue);
40. JPanel north=new JPanel();
41. north.add(ince);
42. north.add(stop);
43. add(north,BorderLayout.NORTH);
44. JPanel center=new JPanel();
45. JScrollPane sp=new JScrollPane(inceAr);
46. JScrollPane sp2=new JScrollPane(inced);
47. inceAr.setLineWrap(true);
48. inceAr.setEditable(false);
49. inced.setLineWrap(true);
50. inced.setEditable(false);
51. center.add(sp);
52. center.add(sp2);
53. add(center,BorderLayout.CENTER);
54. pack(); //JFrame inherited from Window
55. validate();
56. setVisible(true);
57. setDefaultCloseOperation(EXIT_ON_CLOSE);
58. try {
59. socket=new MulticastSocket(port);
60. //A multicast group is specified by a class D IP address
61. //and by a standard UDP port number.
62. //Class D IP addresses are in the range 224.0.0.0 to 239.255.255.255, inclusive.
63. //The address 224.0.0.0 is reserved and should not be used.
64. group=InetAddress.getByName("233.0.0.0");
65. socket.joinGroup(group);
66. packet=new DatagramPacket(buf,buf.length);
68. } catch (IOException e) {
69. // TODO Auto-generated catch block
70. e.printStackTrace();
71. }
73. }
74. @Override
75. public void run(){
76. while(true){
77. try {
78. socket.receive(packet);
79. } catch (IOException e) {
80. // TODO Auto-generated catch block
81. e.printStackTrace();
82. }
83. // String message=new String(buf);
84. String message=new String(packet.getData(),0,packet.getLength());//very important !!
85. // System.out.println(message.length());
86. inceAr.setText("正在接受的內容： \n"+message);
87. inced.append(message+"\n");
88. if(b==true){
89. break;
90. }
91. }
92. }
93. public void actionPerformed(ActionEvent e){
94. Object object=e.getSource();
95. if(object==ince){
96. //If this thread is already on the state "run", do nothing.
97. if(!thread.isAlive()){
98. thread=new Thread(this);
99. thread.start();
100. ince.setBackground(Color.red);
101. stop.setBackground(Color.yellow);
102. b=false;
103. }
104. }
105. if(object==stop){
106. ince.setBackground(Color.yellow);
107. stop.setBackground(Color.red);
108. b=true;
109. }
110. }
111. public static void main(String[] args){
112. @SuppressWarnings("unused")
113. Receive rec=new Receive();
114. // rec.setSize(460, 200);//提供了額外設置窗體大小的方式
115. }
116. }