userlogin.java

图书馆管理系统：该系统的开发主要包括用户登陆

import java.sql.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.event.*;
import java.awt.GridLayout;

 public class userLogin extends JFrame implements ActionListener{
	public userLogin(BookManagerMain bMain)
	{
		myBook=bMain;
		setTitle("用户登陆");
		JPanel panel1=new JPanel();
		panel1.setSize(100,200);
		panel1.setLayout(new GridLayout(3,2,20,20));
		userlbl=new JLabel("用户名");
		passwordlbl=new JLabel("密码");
		usertex=new JTextField("");
		passwordtex=new JPasswordField("");
		surebtn=new JButton("确定");
		cancelbtn=new JButton("取消");
		panel1.add(userlbl);
		panel1.add(usertex);
		panel1.add(passwordlbl);
		panel1.add(passwordtex);
		panel1.add(surebtn);
		panel1.add(cancelbtn);
		getContentPane().add(panel1);
		surebtn.addActionListener(this);
		cancelbtn.addActionListener(this);
	} 
	public void actionPerformed(ActionEvent e)
	{
		Object source=e.getSource();
		if(source==surebtn)
		{
			if(usertex.getText().trim().equals(""))
			{
			JOptionPane.showMessageDialog(null,"用户名不能为空!");
			return;
		}
		if(new String(passwordtex.getPassword()).trim().equals(""))
		{
			JOptionPane.showMessageDialog(null,"密码名不能为空!");
			return;
		}
		String strsql;
		strsql=("select * from 读者权限表 where 用户名='"+usertex.getText().trim()+"'and 密码='"+(new String(passwordtex.getPassword()).trim())+"'");
		rs=db.getResult(strsql);
		
		boolean isexist=false;
		try{
			isexist=rs.first();		
		}
		catch(SQLException w)
		{
			System.out.println(w);}
		if(!isexist){
			JOptionPane.showMessageDialog(null,"用户名不存在,或密码不正确");
			myBook.setEnabled("else");
		}
		else{
			try{
				rs.first();
				myBook.setEnabled(rs.getString("权限").trim());
				this.dispose();
			}
			catch(SQLException es){
			}
		}
		if(source==cancelbtn)
		{
			myBook.setEnabled("");
			this.dispose();
			return;
		}
	}
	if(source==cancelbtn)
		{
			myBook.setEnabled("");
			this.dispose();
			return;
		}
		}
	private BookManagerMain myBook;
	private JLabel userlbl;
	private JLabel passwordlbl;
	private JTextField usertex;
	private JPasswordField passwordtex;
	private JButton surebtn;
	private JButton cancelbtn;
	private GridLayout gl;
	private char[] ch;
	private ResultSet rs;
	private DBManager db=new DBManager();
}