sendandrecievedatainmgframe.java

Java网络编程实例

package sendandrecievedata;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.net.*;

public class sendandrecievedataInMGFrame extends JFrame {
  private JPanel contentPane;
  private TextField textField1 = new TextField();
  private Button button1 = new Button();
  private Label label1 = new Label();
  private Label label2 = new Label();
  int port;                                       //声明组播使用的端口
  MulticastSocket socket;                          //声明建立组播组使用的MulticastSocket类
  InetAddress group;                               //声明建立组播组使用的组播组地址
  DatagramPacket packet;                           //声明发送和接收数据所使用的DatagramPacket类

  //Construct the frame
  public sendandrecievedataInMGFrame() {
    enableEvents(AWTEvent.WINDOW_EVENT_MASK);
    try {
      jbInit();
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }
  //Component initialization
  private void jbInit() throws Exception  {
    //setIconImage(Toolkit.getDefaultToolkit().createImage(sendandrecievedataInMGFrame.class.getResource("[Your Icon]")));
    contentPane = (JPanel) this.getContentPane();            //设计窗体布局
    textField1.setBounds(new Rectangle(88, 127, 240, 32));
    contentPane.setLayout(null);
    this.setSize(new Dimension(400, 300));
    this.setTitle("组播组中发送和接收数据");
    button1.setLabel("发送数据");
    button1.setBounds(new Rectangle(166, 186, 88, 29));
    button1.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(ActionEvent e) {
        button1_actionPerformed(e);
      }
    });
    label1.setBounds(new Rectangle(88, 84, 240, 32));
    label2.setBounds(new Rectangle(88, 41, 220, 32));
    contentPane.add(textField1, null);
    contentPane.add(button1, null);
    contentPane.add(label1, null);
    contentPane.add(label2, null);
    createMulticastGroupAndJoin();
  }
  //Overridden so we can exit when window is closed
  protected void processWindowEvent(WindowEvent e) {
    super.processWindowEvent(e);
    if (e.getID() == WindowEvent.WINDOW_CLOSING) {
      System.exit(0);
    }
  }

  public void createMulticastGroupAndJoin()           //创建一个组播组并加入此组的函数
  {
    try
    {
      port = 5000;                                      //设置组播组的监听端口为5000
      group = InetAddress.getByName("239.0.0.0");       //设置组播组的地址为239.0.0.0
      socket = new MulticastSocket(port);               //初始化MulticastSocket类并将端口号与之关联
      socket.setTimeToLive(1);                          //设置组播数据报的发送范围为本地网络
      socket.setSoTimeout(10000);                       //设置套接字的接收数据报的最长时间
      socket.joinGroup(group);                           //加入此组播组
      label2.setText("已加入地址为239.0.0.0的组播组");
    }
    catch(Exception e1)
    {
      System.out.println("Error: " + e1);               //捕捉异常情况
    }
  }

  public void sendData()                                //向组播组发送数据的函数
  {
    try
    {
      byte[] data = textField1.getText().getBytes();       //将用户所要发送的数据转换为字节形式并存储在数组中
      packet = new DatagramPacket(data, data.length, group, port);    //初始化DatagramPacket的实例
      socket.send(packet);                                   //通过MulticastSocket实例端口向组播组发送数据
    }
    catch(Exception e1)
    {
      System.out.println("Error: " + e1);                   //捕捉异常情况
    }
  }

  public String recieveData()                             //从组播组接收数据的函数
  {
    String message;
    try
    {
      packet.setData(new byte[512]);                      //设定接收数据的DatagramPacket实例的数组大小
      packet.setLength(512);                               //设定接收数据的DatagramPacket实例的长度
      socket.receive(packet);                              //通过MulticastSocket实例端口从组播组接收数据
      message = new String(packet.getData(), 0, packet.getLength());  //将接受的数据转换成字符串形式
    }
    catch(Exception e1)
    {
      System.out.println("Error: " + e1);                   //捕捉异常情况
      message = "Error: " + e1;
    }
    return message;
  }

  void button1_actionPerformed(ActionEvent e) {
    sendData();                                             //首先向组播组发送数据
    String message = recieveData();                         //然后从组播组接受此数据
    label1.setText("Data recieved: '" + message + "'");     //本机显示接收到的数据
  }
}