Java 模拟一个桌面登录窗口

桌面登录窗口

首先定义一个Login类继承JFrame类
在Java中，要定义一个桌面窗口，就得继承JFrame类，我们知道，Java是面向对象编程语言，也就是在java中万事万物皆对象，窗口在Java中也被定义为一个对象。自定义一个窗口类需要继承JFrame类

package com.test.ddz;

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.beans.PropertyChangeListener;

import javax.swing.Action;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPasswordField;
import javax.swing.JTextField;

public class Login extends JFrame {
  //窗口上的组件就是窗口的属性
  JLabel unameJLabel;
  JLabel pwdJLabel;
  JTextField unameJTextField;
  JPasswordField pwdJTextField;
  JButton loginJButton;
  JButton cancelJButton;
  //初始化组件的信息和窗口信息
  public Login(String title) {
    //显示调用父类的有参构造函数
    super(title);
    //创建用户名标签
    this.unameJLabel = new JLabel("用户名");
    //创建密码标签
    this.pwdJLabel = new JLabel("密码");
    //创建用户名文本框
    this.unameJTextField = new JTextField();
    //创建密码文本框
    this.pwdJTextField = new JPasswordField();
    //创建登录和取消按钮
    this.loginJButton = new JButton("登录");
    this.cancelJButton = new JButton("取消");
    
    //设置布局
    this.setLayout(new GridLayout(3,2));
    
    //创建一个内部类对象（监听对象）监视登录按钮
    MyEvent myEvent = new MyEvent();
    //给按钮添加一个监听接口
    this.loginJButton.addActionListener(myEvent);
    
    //将组件添加到窗口中
       this.add(this.unameJLabel);
       this.add(this.unameJTextField);
       this.add(this.pwdJLabel);
       this.add(this.pwdJTextField);
       this.add(this.loginJButton);
       this.add(this.cancelJButton);
       
       this.setSize(400,300);
       
       this.setLocationRelativeTo(null);
      
       this.setVisible(true);
       
       this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    
  }
  
  //创建一个内部类对象 实现action接口 目的是创建一个监听器对象 监听按钮的行为
  class MyEvent implements Action
  {
    //监视单机的行为
    @Override
    public void actionPerformed(ActionEvent e) {
      // TODO Auto-generated method stub
      //JOptionPane.showMessageDialog(null,unameJTextField.getText());
      String uname = unameJTextField.getText();
      
      String pwd = new String(pwdJTextField.getPassword());
      
      if(uname.equals("test") && pwd.equals("666")) {
        //JOptionPane.showMessageDialog(null, "跳到主窗口");
        new MainFrame();
      }else {
        JOptionPane.showMessageDialog(null, "用户名或密码出错");
      }
    }

    @Override
    public Object getValue(String key) {
      // TODO Auto-generated method stub
      return null;
    }

    @Override
    public void putValue(String key, Object value) {
      // TODO Auto-generated method stub
      
    }

    @Override
    public void setEnabled(boolean b) {
      // TODO Auto-generated method stub
      
    }

    @Override
    public boolean isEnabled() {
      // TODO Auto-generated method stub
      return false;
    }

    @Override
    public void addPropertyChangeListener(PropertyChangeListener listener) {
      // TODO Auto-generated method stub
      
    }

    @Override
    public void removePropertyChangeListener(PropertyChangeListener listener) {
      // TODO Auto-generated method stub
      
    }
    
  }
}

再定义一个MainFrame类，也继承JFrame类

package com.test.ddz;

import javax.swing.JFrame;

public class MainFrame extends JFrame {
  
  private MyPanel myPanel;
  
  public MainFrame() {
    super("测试窗口");
    
    this.myPanel = new MyPanel();
    
    this.myPanel.setBounds(0,0,1200,700);
    
    this.add(myPanel);
    
    this.setSize(1200,700);
    this.setLocationRelativeTo(null);
    this.setVisible(true);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }
}

在MainFrame窗口类上设置画布，所以再定义一个画布，MyPanel类

package com.test.ddz;

import java.awt.Graphics;
import java.awt.Image;

import javax.swing.ImageIcon;
import javax.swing.JPanel;

public class MyPanel extends JPanel{
  
  protected void paintComponent(Graphics g) {
    
    Image image = new ImageIcon("images/bg/bg1.png").getImage();
    
    g.drawImage(image,0,0,this.getWidth(),this.getHeight(),null);
    
  }

}

创建main方法，new一个Login对象

package com.test.ddz;

public class Test {
  public static void main(String[] args) {
    new Login("测试登录");
  }
}

运行效果