denlu.java

创建一个数据库dbstu,其中包括下列表： １.student(学号

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
class Denlu extends JDialog implements ActionListener 
{static int bianliang=0;
		JPanel p1=new JPanel();              //定义并建立面板
	JPanel p2=new JPanel();
	JPanel p3=new JPanel();
	JPanel p4=new JPanel();
	JPanel p5=new JPanel();
	JTextField txtUserName=new JTextField(15);            //用户名文本框
	JPasswordField txtPassWord=new JPasswordField(15);  //密码域
	JButton ok=new JButton("确定");
	JButton cancel=new JButton("取消");
	public Denlu()
	{	setModal(true);                       //设置模态
		setBackground(Color.LIGHT_GRAY);  //设置背景色
		Container contentPane=this.getContentPane();         //取出内容面板
		contentPane.setLayout(new GridLayout(5,1));          //设置布局为5行1列
		p2.add(new JLabel("用户名："));p2.add(txtUserName);  //将组件添加到中间容器
		p3.add(new JLabel("密　码："));p3.add(txtPassWord);
		p4.add(ok);p4.add(cancel);
		ok.addActionListener(this);   //注册事件接听者
		cancel.addActionListener(this);
		txtUserName.addActionListener(this);
		txtPassWord.addActionListener(this);
        contentPane.add(p1);       //将面板添加到内容面板
        contentPane.add(p2);
        contentPane.add(p3);
        contentPane.add(p4);
        contentPane.add(p5);
        setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);  //设置自动关闭窗口
        setSize(300, 220);                                        //设置窗口的大小
        Dimension screen=Toolkit.getDefaultToolkit().getScreenSize(); 
        setLocation((screen.width-300)/2,(screen.height-220)/2);      
		setTitle("登录窗口");
		setResizable(false);        //不让用户改变窗口的大小
        setVisible(true);
JFrame.setDefaultLookAndFeelDecorated(true);
     Font font = new Font("JFrame", Font.PLAIN, 14);
     Enumeration keys = UIManager.getLookAndFeelDefaults().keys();
     while (keys.hasMoreElements()) {
       Object key = keys.nextElement();
       if(UIManager.get(key) instanceof Font)UIManager.put(key, font);
     }	}
	
	public void actionPerformed(ActionEvent e)
	{	if(e.getSource()==ok||e.getSource()==txtPassWord)//单击确定按钮或密码域中按回车   
		{	if(txtUserName.getText().trim().equals("jiangyan")&&txtPassWord.getText().trim().equals("jiangyan"))
	  		{//new Windowm();	               //关闭登录窗口
	  			new Jcaidan();//
	  			dispose();//	new MainWindow();    //调出主窗口
		//	LoginWindow.setDefaultCloseOperation(HIDE_ON_CLOSE);
		//.setDefaultLookAndFeelDecorated(false);	//
			}
			else if(bianliang==2)
	{JOptionPane.showMessageDialog(null,"你不是合法用户");
		dispose();	}
			else   
			{	JOptionPane.showMessageDialog(null,"用户名或密码错误!");
				txtUserName.requestFocus();           //设置焦点
				txtUserName.setSelectionStart(0);    //设置选中文本开始位置
				txtUserName.setSelectionEnd(txtUserName.getText().length());//设置选中长度
			bianliang++;}
			
		}    
		else if(e.getSource()==cancel) //单击取消按钮
		{	dispose();                         //关闭窗口
			System.exit(0);                   //退出程序	
		}
		else if(e.getSource()==txtUserName)  //在用户名文本框按回车焦点移到密码域
			txtPassWord.requestFocus();//
	
	}
/*	public static void main(String args[])
	{	JDialog.setDefaultLookAndFeelDecorated(true);
  		Font font = new Font("JFrame", Font.PLAIN, 14);
        Enumeration keys = UIManager.getLookAndFeelDefaults().keys();
        while(keys.hasMoreElements()) 
        {	Object key = keys.nextElement();
            if(UIManager.get(key) instanceof Font) 
            {	UIManager.put(key, font);
			}
		}
	 	new Denlu();
	}*/
}