dataexchangetest.java

Java程序设计实验与实训源代码经典的JAVA学习教材

//DataExchangeTest.java
//一个能进行数据交流的图形界面程序
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class DataExchangeTest
{
   public static void main(String[] args)
   {  
      DataExchangeFrame frame = new DataExchangeFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.show();
   }
}
//菜单的框架，包含"File"关联，显示一个关键词对话
class DataExchangeFrame extends JFrame 
{  
   public DataExchangeFrame()
   {
      setTitle("数据交流测试");
      setSize(WIDTH, HEIGHT);
      // 构造一个文件菜单      
      JMenuBar mbar = new JMenuBar();
      setJMenuBar(mbar);
      JMenu fileMenu = new JMenu("文件");
      mbar.add(fileMenu);
      // 增加连接和返回按钮项目
      JMenuItem connectItem = new JMenuItem("连接");
      connectItem.addActionListener(new ConnectAction());
      fileMenu.add(connectItem);
      // Exit 项目的返回程序
      JMenuItem exitItem = new JMenuItem("返回");
      exitItem.addActionListener(new
         ActionListener()
         {
            public void actionPerformed(ActionEvent event)
            {
               System.exit(0);
            }
         });
      fileMenu.add(exitItem);

      textArea = new JTextArea();
      getContentPane().add(new JScrollPane(textArea), 
         BorderLayout.CENTER);
   }

   public static final int WIDTH = 300;
   public static final int HEIGHT = 200;  

   private PasswordChooser dialog = null;
   private JTextArea textArea;

   //连接程序取回对话密码.
      private class ConnectAction implements ActionListener
   {
      public void actionPerformed(ActionEvent event)
      {
         // 若用户首先连接对话框

         if (dialog == null) 
            dialog = new PasswordChooser();
         
         // 设置默认值
         dialog.setUser(new User("姓名", null));

         // 中断对话
         if (dialog.showDialog(DataExchangeFrame.this, 
            "Connect"))
         {
            // 若连接完毕，接受用户输入
            User u = dialog.getUser();
            textArea.append(
               "用户姓名 = " + u.getName()
               + ", 密码= " + (new String(u.getPassword()))
               + "\n");
         }
      }
   }
}

// 密码选择框它显示在对话框的内层
class PasswordChooser extends JPanel 
{  
   public PasswordChooser()
   {  
      setLayout(new BorderLayout());

      // 构造一个面板显示用户姓名和密码

      JPanel panel = new JPanel();
      panel.setLayout(new GridLayout(2, 2));
      panel.add(new JLabel("用户姓名:"));
      panel.add(username = new JTextField(""));
      panel.add(new JLabel("密码:"));
      panel.add(password = new JPasswordField(""));
      add(panel, BorderLayout.CENTER);

      // 创建 Ok and Cancel 命令钮由它们终止对话
      
      JButton okButton = new JButton("Ok");
      okButton.addActionListener(new
         ActionListener()
         {
            public void actionPerformed(ActionEvent event)
            {
               ok = true;
               dialog.setVisible(false);
            }
         });

      JButton cancelButton = new JButton("Cancel");
      okButton.addActionListener(new
         ActionListener()
         {
            public void actionPerformed(ActionEvent event)
            {
               dialog.setVisible(false);
            }
         });

      // 增加按钮到边界

      JPanel buttonPanel = new JPanel();
      buttonPanel.add(okButton);
      buttonPanel.add(cancelButton);
      add(buttonPanel, BorderLayout.SOUTH);
   }

   //设置对话默认程序u,默认用户信息
   public void setUser(User u)
   {
      username.setText(u.getName());
   }

   //得到用户对话后，反馈用户声明描述对话的信息 
   public User getUser()
   {
      return new User(username.getText(), 
         password.getPassword());
   }

   //在对话程序面板显示选择框构成对话窗口的信息
   public boolean showDialog(Component parent, String title)
   {  
      ok = false;

      // 查找所拥有的对话框

      Frame owner = null;
      if (parent instanceof Frame)
         owner = (Frame) parent;
      else 
         owner = (Frame)SwingUtilities.getAncestorOfClass(
            Frame.class, parent);

      // 若某时或用户已经改变，制造一个新的对话框
      
      if (dialog == null || dialog.getOwner() != owner) 
      {      
         owner = null;
         dialog = new JDialog(owner, true);
         dialog.getContentPane().add(this);
         dialog.pack();
      }

      // 设置标题和显示对话

      dialog.setTitle(title);
      dialog.show();
      return ok;
   }

   private JTextField username;
   private JPasswordField password;
   private boolean ok;
   private JDialog dialog;
}

//用户已经登记姓名和密码，存储信息在数组
class User
{
   public User(String aName, char[] aPassword)
   {
      name = aName;
      password = aPassword;
   }
   
   public String getName() { return name; }
   public char[] getPassword() { return password; }

   public void setName(String aName) { name = aName; }
   public void setPassword(char[] aPassword) 
   { password = aPassword; }

   private String name;
   private char[] password;
}