//DataExchangeTest.java
//一個能進行數據交流的圖形界面程序
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();
   }
}
//菜單的框架，包含"File"關聯，顯示一個關鍵詞對話
class DataExchangeFrame extends JFrame 
{  
   public DataExchangeFrame()
   {
      setTitle("數據交流測試");
      setSize(WIDTH, HEIGHT);
      // 構造一個文件菜單      
      JMenuBar mbar = new JMenuBar();
      setJMenuBar(mbar);
      JMenu fileMenu = new JMenu("文件");
      mbar.add(fileMenu);
      // 增加連接和返回按鈕項目
      JMenuItem connectItem = new JMenuItem("連接");
      connectItem.addActionListener(new ConnectAction());
      fileMenu.add(connectItem);
      // Exit 項目的返回程序
      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;

   //連接程序取回對話密碼.
      private class ConnectAction implements ActionListener
   {
      public void actionPerformed(ActionEvent event)
      {
         // 若用戶首先連接對話框

         if (dialog == null) 
            dialog = new PasswordChooser();
         
         // 設置默認值
         dialog.setUser(new User("姓名", null));

         // 中斷對話
         if (dialog.showDialog(DataExchangeFrame.this, 
            "Connect"))
         {
            // 若連接完畢，接受用戶輸入
            User u = dialog.getUser();
            textArea.append(
               "用戶姓名 = " + u.getName()
               + ", 密碼= " + (new String(u.getPassword()))
               + "\n");
         }
      }
   }
}

// 密碼選擇框它顯示在對話框的內層
class PasswordChooser extends JPanel 
{  
   public PasswordChooser()
   {  
      setLayout(new BorderLayout());

      // 構造一個面板顯示用戶姓名和密碼

      JPanel panel = new JPanel();
      panel.setLayout(new GridLayout(2, 2));
      panel.add(new JLabel("用戶姓名:"));
      panel.add(username = new JTextField(""));
      panel.add(new JLabel("密碼:"));
      panel.add(password = new JPasswordField(""));
      add(panel, BorderLayout.CENTER);

      // 創建 Ok and Cancel 命令鈕由它們終止對話
      
      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);
            }
         });

      // 增加按鈕到邊界

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

   //設置對話默認程序u,默認用戶信息
   public void setUser(User u)
   {
      username.setText(u.getName());
   }

   //得到用戶對話后，反饋用戶聲明描述對話的信息 
   public User getUser()
   {
      return new User(username.getText(), 
         password.getPassword());
   }

   //在對話程序面板顯示選擇框構成對話窗口的信息
   public boolean showDialog(Component parent, String title)
   {  
      ok = false;

      // 查找所擁有的對話框

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

      // 若某時或用戶已經改變，制造一個新的對話框
      
      if (dialog == null || dialog.getOwner() != owner) 
      {      
         owner = null;
         dialog = new JDialog(owner, true);
         dialog.getContentPane().add(this);
         dialog.pack();
      }

      // 設置標題和顯示對話

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

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

//用戶已經登記姓名和密碼，存儲信息在數組
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;
}