Java實現一個登錄窗體功能

This program shows a "Login" window based on Swing JFrame. When you input the correct userID and Password, you can obtain a confirmation, or else you will be alerted by a JAVA standard message window.

The Swing JFrame used in the same time the GridLayout for the Container and the FlowLayout for the JPanel.

1. package com.han;  
2.   
3. import java.awt.Container;  
4. import java.awt.FlowLayout;  
5. import java.awt.GridLayout;  
6. import java.awt.event.ActionEvent;  
7. import java.awt.event.ActionListener;  
8. import java.util.Arrays;  
9.   
10. import javax.swing.*;  
11.   
12. /** 
13.  * This program shows a "Login" window based on Swing JFrame. 
14.  * When you input the correct userID and Password, you can obtain a confirmation, 
15.  * or else you will be alerted by a JAVA standard message window. 
16.  * <p> 
17.  * The Swing JFrame used in the same time the GridLayout for the Container and the FlowLayout for the JPanel. 
18.  * @author han 
19.  * 
20.  */  
21. public class SwingJFrameLogin {  
22.     /*define all the necessary member variables*/  
23.     String s1=null;  
24.     char[] s2=null;  
25.     JFrame frame=new JFrame();  
26.     Container c=frame.getContentPane();  
27.     /*the construct function*/  
28.     public SwingJFrameLogin() {  
29.         c.setLayout(new GridLayout(3,1,10,10));//the Container uses the GridLayout for 3 JPanels    
30.         JPanel panel1=new JPanel(new FlowLayout(FlowLayout.CENTER));//each JPanel uses the FlowLayout   
31.         JPanel panel2=new JPanel(new FlowLayout(FlowLayout.CENTER));  
32.         JPanel panel3=new JPanel(new FlowLayout());  
33.         JLabel label1=new JLabel("用戶名：");  
34.         final JTextField jt=new JTextField(10);  
35.         JLabel label2=new JLabel("密碼：");  
36.         final JPasswordField jp=new JPasswordField(6);  
37.         jp.setEchoChar((char) 0);//set the display words as visible.   
38.         final JButton jb1 = new JButton("提交");  
39.         final JButton jb2 = new JButton("重置");  
40.         panel1.add(label1);  
41.         panel1.add(jt);  
42.         panel2.add(label2);  
43.         panel2.add(jp);  
44.         panel3.add(jb1);  
45.         panel3.add(jb2);  
46.         c.add(panel1);  
47.         c.add(panel2);  
48.         c.add(panel3);        
49.         jb1.addActionListener(new ActionListener(){  
50.             @Override  
51.             public void actionPerformed(ActionEvent e) {  
52.                 String s1=jt.getText();  
53.                 char[] s2=jp.getPassword();  
54.                 System.out.println(s1);  
55.                 System.out.println(s2);  
56.                 char[] pw={'u','p','s'};  
57.                 /*System.out.println(Arrays.equals(s2,pw)); 
58.                 System.out.println(s1.equals("han"));*/  
59.                 if (s1.equals("han") && Arrays.equals(s2,pw)) {  
60.                     JOptionPane.showMessageDialog(frame,  
61.                             "登錄成功 ！","Message",JOptionPane.INFORMATION_MESSAGE);  
62.                     //frame.dispose();（等同於點擊關閉窗口時執行frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE );）   
63.                     System.exit(0);//正常退出（等同於點擊關閉窗口時執行frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE );）   
64.                 }  
65.                 else {                    
66.                     JOptionPane.showMessageDialog(frame,//it is a JAVA internal STD message BOX   
67.                             "You had input a wrong userID !!","Warning",JOptionPane.WARNING_MESSAGE);                     
68.                 }  
69.                 Arrays.fill(s2,'0'); //Zero out the possible password, for security.   
70.             }             
71.         });  
72.         jb2.addActionListener(new ActionListener(){  
73.             @Override  
74.             public void actionPerformed(ActionEvent e) {//set all the fields empty.   
75.                 jt.setText("");  
76.                 jp.setText("");               
77.             }         
78.         });  
79.         frame.pack();//automatically resize all the components to their preferred sizes.   
80.         frame.setVisible(true);  
81.         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE );  
82.     }  
83.       
84.     public static void main(String[] args) {  
85.         new SwingJFrameLogin();  
86.     }  
87. }