logindialogdemo.java

java2参考大全上的例子的源码和自己的理解.

package LoginDialogDemo;

//LoginDialogDemo.java
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class LoginDialogDemo
    extends JFrame {
  JButton button = new JButton("Click Me");
  JPanel panel = new JPanel(new FlowLayout());

  public LoginDialogDemo() {
    final JFrame frame = this;
    this.getContentPane().add(panel, BorderLayout.SOUTH);
    panel.add(button);
    button.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        showLoginDialog(frame);
      }
    });
    this.setSize(300, 200);
    this.setTitle("显示登陆对话框");
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.show();
  }

  void showLoginDialog(JFrame frame) {
    JPanel p = new JPanel(new GridLayout(0, 1));
    JTextField tfUserName = new JTextField();
    JPasswordField tfPassword = new JPasswordField();
    p.add(new JLabel("Username: "));
    p.add(tfUserName);
    p.add(new JLabel("Password: "));
    p.add(tfPassword);
    /*
         JOptionPane makes it easy to pop up a standard dialog box that prompts users for a value or
         informs them of something. For information about using JOptionPane, see How to Make Dialogs,
         a section in The Java Tutorial.
     */
    /*
         public static int showConfirmDialog(Component\u00A0parentComponent,
                                         Object\u00A0message,
                                         String\u00A0title,
                                         int\u00A0optionType,
                                         int\u00A0messageType)
                                  throws HeadlessException
         Parameters:
         parentComponent - determines the Frame in which the dialog is displayed;
           if null, or if the parentComponent has no Frame, a default Frame is used.
         message - the Object to display
         title - the title string for the dialog
         optionType - an integer designating the options available on the dialog: YES_NO_OPTION, or YES_NO_CANCEL_OPTIO
         NmessageType - an integer designating the kind of message this is; primarily used to determine the icon from the pluggable Look and Feel: ERROR_MESSAGE, INFORMATION_MESSAGE, WARNING_MESSAGE, QUESTION_MESSAGE, or PLAIN_MESSAGE
     */
    if (JOptionPane.showConfirmDialog(frame // may want to pass your application frame here
                                      , p
                                      , "Login"
                                      , JOptionPane.OK_CANCEL_OPTION
                                      , JOptionPane.PLAIN_MESSAGE
                                      ) == JOptionPane.OK_OPTION) {
      System.out.println("User Name:" + tfUserName.getText());
      System.out.println("Password:" + new String(tfPassword.getPassword()));
    }
  }

  public static void main(String[] args) {
    LoginDialogDemo frame = new LoginDialogDemo();
  }
}