Swing 示例 - 更改密码字符

以下示例展示了如何在 Java Swing 应用程序中更改密码字段的回显字符。

我们正在使用的 API 如下。

• JPasswordField - 创建密码字段。

• JPasswordField.getPassword() - 获取密码。

• JPasswordField.setEchoChar('<') - 设置密码字段的回显字符。

示例

package com.tutorialspoint.gui;
 
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
public class SwingControlDemo {
   private JFrame mainFrame;
   private JLabel headerLabel;
   private JLabel statusLabel;
   private JPanel controlPanel;

   public SwingControlDemo(){
      prepareGUI();
   }
   public static void main(String[] args){
      SwingControlDemo  swingControlDemo = new SwingControlDemo();      
      swingControlDemo.showPasswordFieldDemo();
   }
   private void prepareGUI(){
      mainFrame = new JFrame("Java Swing Examples");
      mainFrame.setSize(400,400);
      mainFrame.setLayout(new GridLayout(3, 1));
      
      mainFrame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
            System.exit(0);
         }        
      });    
      headerLabel = new JLabel("", JLabel.CENTER);        
      statusLabel = new JLabel("",JLabel.CENTER);    
      statusLabel.setSize(350,100);

      controlPanel = new JPanel();
      controlPanel.setLayout(new FlowLayout());

      mainFrame.add(headerLabel);
      mainFrame.add(controlPanel);
      mainFrame.add(statusLabel);
      mainFrame.setVisible(true);  
   }
   private void showPasswordFieldDemo(){
      headerLabel.setText("Control in action: JPasswordField"); 

      JLabel namelabel= new JLabel("User ID: ", JLabel.RIGHT);
      JLabel passwordLabel = new JLabel("Password: ", JLabel.CENTER);
      final JTextField userText = new JTextField(6);
      final JPasswordField passwordText = new JPasswordField(6);      
      passwordText.setEchoChar('~');
	  
      JButton loginButton = new JButton("Login");
      loginButton.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {     
            String data = "Username " + userText.getText();
            data += ", Password: " + new String(passwordText.getPassword()); 
            statusLabel.setText(data);        
         }
      }); 
      controlPanel.add(namelabel);
      controlPanel.add(userText);
      controlPanel.add(passwordLabel);       
      controlPanel.add(passwordText);
      controlPanel.add(loginButton);
      mainFrame.setVisible(true);  
   }
}

使用命令提示符编译该程序。转到 D:/ > SWING，并键入以下命令。

D:\SWING>javac com\tutorialspoint\gui\SwingControlDemo.java

如果没有发生错误，则表示编译成功。使用以下命令运行该程序。

D:\SWING>java com.tutorialspoint.gui.SwingControlDemo

验证以下输出。