userlogin.java

用JAVA做的图书借阅信息系统

import java.awt.*;
import java.sql.*;
import java.awt.event.*;
public class UserLogin extends Dialog implements ActionListener
{
	int inputtimes=0;
	Button 确认,退出;
	Label l1,l2;
	TextField password,username;
	Panel p;
	Label message;
	Connection con;
    Statement sql;
    ResultSet rs;
	UserLogin(Frame f,String s,boolean b)
	{
		super(f,s,b);
		p=new Panel();
		GridLayout net=new GridLayout(4,2);
		net.setHgap(5);
		net.setVgap(30);
		p.setLayout(net);
		确认=new Button("确认");
		退出=new Button("退出");
		l1=new Label("请输入用户名：",Label.RIGHT);
		l2=new Label("请输入用户密码：",Label.RIGHT);
		password=new TextField(10);
		password.setEchoChar('*');
		username=new TextField(10);
		p.add(l1);p.add(username);
		p.add(l2);p.add(password);;
		p.add(确认);p.add(退出);
		message=new Label("",Label.CENTER);
		add(message,"South");
		add(new Label(),"North");
		add(new Label("             "),"East");
		add(new Label("             "),"West");
		add(p,"Center");
		确认.addActionListener(this);
		退出.addActionListener(this);
		setBounds(210,120,400,250);
		validate();
	}
	public void actionPerformed(ActionEvent e)
	{
		if(e.getSource()==确认)
		{
			inputtimes++;
			String name=username.getText().trim();
			String pass=password.getText().trim();
			try
			{
				Class.forName("com.ms.jdbc.odbc.JdbcOdbcDriver");
			}
			catch(ClassNotFoundException e1)
			{
				message.setText("无法建立数据源！");
			}
			try
			{
				con=DriverManager.getConnection("jdbc:odbc:book","","");
				sql=con.createStatement();
			}
			catch(SQLException e2)
			{
				message.setText("没有找到数据表！");
			}
			try
			{
				rs=sql.executeQuery("SELECT 用户名,密码 FROM 用户信息表");
				boolean b=false;
				while ((b=rs.next())==true)
				{
					String tname=rs.getString("用户名");
					String tpass=rs.getString("密码");
					if(tname.equals(name)&&tpass.equals(pass))
					{
						setVisible(false);
						dispose();
						//con.close();
						new MainMenu();
					}
					else
					{
						Color c1=this.getBackground();
						if(inputtimes<=3)
						{
							message.setBackground(Color.red);
							message.setText("输入有误，重新输入！");
							try
							{
								Thread.sleep(3000);
								username.setText("");
								password.setText("");
								message.setBackground(c1);
								message.setText("");
							}
							catch(InterruptedException ee){}
						}
						else
						{
							message.setBackground(Color.red);
							message.setText("您不是合法用户，不能使用本系统！");
							try
							{
								Thread.sleep(3000);
							}
							catch(InterruptedException ee){}
							setVisible(false);
							System.exit(0);
						}				
						
					}
				}
				
			}
			catch(SQLException e3){}			
		}
		if(e.getSource()==退出)
		{
			setVisible(false);
			System.exit(0);
		}
	}
}