login.java

中小型书店管理系统,主要是为了方便书店的管理而编写的管理系统.

import java.awt.*;
import java.awt.event.*;
import java.sql.*;

import javax.swing.*;


public class Login extends JFrame {
	private Container container;
	private GridBagLayout layout;
	private GridBagConstraints constraints;
	private JPanel panel;
	private JTextField textField;
	private JPasswordField passwordField;
	private String user,pwd,type;
	private boolean found = false;
	private int fault;
	private JLabel label1,label2;
	private JButton login,logout;
	
	public Login()
	{
		super( "登录" );
		
		container = getContentPane();
		layout = new GridBagLayout();
		
		constraints = new GridBagConstraints();
		
		panel = new JPanel();
		panel.setLayout( layout );
		
		label1 = new JLabel( "用户名" );
		label2 = new JLabel( "密码" );
		textField = new JTextField( 12 );
		passwordField = new JPasswordField( 12 );
		login = new JButton( "登录" );
		logout = new JButton( "退出" );	
			
//		JRadioButton manager = new JRadioButton( "管理员", true );
//		JRadioButton seller = new JRadioButton( "售货员", false );

		addComponent( label1, 0, 0, 4, 1 );
		addComponent( label2, 1, 0, 4, 1 );
		addComponent( textField, 0, 4, 6, 1 );
		addComponent( passwordField, 1, 4, 6, 1 );
//		addComponent( manager, 2, 0, 5, 1 );
//		addComponent( seller, 2, 5, 5, 1 );
		addComponent( login, 3, 0, 5, 1 );
		addComponent( logout, 3, 5, 5, 1 );
		
//		ButtonGroup radioGroup = new ButtonGroup();
//		radioGroup.add( manager );
//		radioGroup.add( seller );
		
		login.addActionListener(
			new ActionListener() {
				public void actionPerformed( ActionEvent event )
				{
					user = textField.getText();
					pwd = new String( passwordField.getPassword() );
					try{ 
					Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); 
					String url="jdbc:odbc:access"; 
					Connection connection=DriverManager.getConnection(url); 
					Statement statement = connection.createStatement(); 
					String sql="select * from User"; 
					ResultSet rs = statement.executeQuery(sql); 
					while( rs.next() ){
						if( user.compareTo( "" ) == 0 ) fault = 0;
						else if( pwd.compareTo( "" )==0 ) fault = 1;
						else if( user.compareTo( rs.getString( "User_id" ) ) == 0 ){
							if( pwd.compareTo( rs.getString( "Password" ) ) == 0 ){
								type = rs.getString( "User_type" );
								found = true;
							}
							else fault = 2;
						}
						else fault = 3;	
	
					}
					if( found ){
						if( type.compareTo( "M" ) == 0 )
						Manager1.main( null );
						else if( type.compareTo( "S" ) == 0 ) Sell.main( null );
						Login.this.setVisible( false );
					}
					else if( fault == 0 ){
						JOptionPane.showMessageDialog( null,"请输入用户名","错误",JOptionPane.ERROR_MESSAGE );
						passwordField.setText("");
					}
					else if( fault == 1 ){
						JOptionPane.showMessageDialog( null,"请输入密码","错误",JOptionPane.ERROR_MESSAGE );
						passwordField.setText("");
					}
					else if( fault == 2 ){
						JOptionPane.showMessageDialog( null,"密码错误,请重输","错误",JOptionPane.ERROR_MESSAGE );
						passwordField.setText("");
					}
					else if( fault == 3 ){
						JOptionPane.showMessageDialog( null,"用户名不存在,请重输","错误",JOptionPane.ERROR_MESSAGE );
						textField.setText( null );
						passwordField.setText( null );
					}

					rs.close(); 
					connection.close(); 
					} 
					catch(Exception ex){ 
					System.out.println(ex); 
					}
				}
			}
		);
		
		logout.addActionListener(
			new ActionListener() {
				public void actionPerformed( ActionEvent event )
				{
					System.exit( 0 );
				}
			}
		);
		
		container.add( panel );	
		
		setSize( 500,500 );
		setVisible( true );
	}	

	
	
	private void addComponent( Component component, int row,
							   int column, int width, int height )
	{
		constraints.gridx = column;
		constraints.gridy = row;
		constraints.gridwidth = width;
		constraints.gridheight = height;
		layout.setConstraints( component, constraints );
		panel.add( component );
	}
	
	public static void main( String args[] )
	{
		
		Login application = new Login();
		
		application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
	}
	
}