Java Swing 用户登录界面

package JAVA_1;

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
import javax.swing.SwingConstants;

public class Login extends JFrame implements ActionListener
{
	JButton login = new JButton("登录");
	JButton exit = new JButton("退出");
	JLabel  name = new JLabel("用户名：");
	JLabel password = new JLabel("密码："); 
	JTextField JName = new JTextField(10); //明文账号输入
	JPasswordField JPassword = new JPasswordField(10); // 非明文密码输入；
	
	public Login() 
	{
		JPanel jp = new JPanel();
		jp.setLayout(new GridLayout(3,2));  //3行2列的面板jp（网格布局）
		
		name.setHorizontalAlignment(SwingConstants.RIGHT);  //设置该组件的对齐方式为向右对齐
		password.setHorizontalAlignment(SwingConstants.RIGHT);
		
		jp.add(name);   //将内容加到面板jp上
		jp.add(JName);  
		jp.add(password);
		jp.add(JPassword);  
		jp.add(login);
		jp.add(exit);
		
		login.addActionListener(this); //登录增加事件监听
		exit.addActionListener(this);	//退出增加事件监听
		
		this.add(jp,BorderLayout.CENTER);	//将整块面板定义在中间
		
		this.setTitle("登录窗口");
		this.setLocation(500,300);	//设置初始位置
		this.pack();  		//表示随着面板自动调整大小
		this.setVisible(true);
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}
	public void actionPerformed(ActionEvent e)  // 对时间进行处理
	{
		if(e.getSource() == exit)
		{
			int i = JOptionPane.showConfirmDialog(null,"确认要退出吗？", "确认", JOptionPane.YES_NO_OPTION);
			// 显示选择对话框
			if(i == JOptionPane.YES_OPTION);
			System.exit(0);
		}
		else
		{
			if(JName.getText().equals("admin")&& String.valueOf(JPassword.getPassword()).equals("admin"))
			{
				JOptionPane.showMessageDialog(null, "登录成功，欢迎到来！");
				//显示信息提示框
				System.exit(0);
			}
			else 
			{
				JOptionPane.showMessageDialog(null, "用户或密码错误！请从新登录！");
				//显示信息提示框
				JName.setText(""); 
				JPassword.setText("");
			}
		}
	}
	public static void main(String[] args)
	{
		JFrame.setDefaultLookAndFeelDecorated(true);
		new Login();
	}
}