loginframe.java

由java编写的学生选课管理系统

import java.sql.*;
import java.io.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.border.*;
import javax.swing.table.*;


/**
  a logining frame with a Logining panel
*/

public class LoginFrame extends JFrame
{
	public LoginFrame()
	{
		setTitle("登录窗口");
    setResizable(false);
		setLocation(350,200);
		setSize(DEFAULT_WIDTH,DEFAULT_HEIGHT);
		
    //add main panel to frame
	
		JPanel mainPanel = new JPanel(new GridBagLayout());
		constraints = new GridBagConstraints();
		
		label1 = new JLabel("用户帐号", new ImageIcon("01.gif"), SwingConstants.CENTER);
		constraints.weightx = 100;
		constraints.weighty = 100;
		constraints.gridx = 0;
		constraints.gridx = 0;
		constraints.gridwidth = 1;
		constraints.gridheight = 1;
		mainPanel.add(label1,constraints);
		
		myTextField = new JTextField();
		myTextField.setPreferredSize(new Dimension(120, 25));
		constraints.gridx = 0;
		constraints.gridx = 1;
		constraints.gridwidth = 1;
		constraints.gridheight = 1;
		mainPanel.add(myTextField,constraints);
		
		label2 = new JLabel("登录密码", new ImageIcon("02.gif"), SwingConstants.CENTER);
		constraints.gridx = 1;
		constraints.gridx = 0;
		constraints.gridwidth = 1;
		constraints.gridheight = 1;
		mainPanel.add(label2,constraints);
		
		passwordField = new JPasswordField();
		passwordField.setPreferredSize(new Dimension(120, 25));
		constraints.gridx = 1;
		constraints.gridx = 1;
		constraints.gridwidth = 1;
		constraints.gridheight = 1;
		mainPanel.add(passwordField,constraints);
		
		label3 = new JLabel("用户类型", new ImageIcon("03.gif"), SwingConstants.CENTER);
		constraints.gridx = 2;
		constraints.gridx = 0;
		constraints.gridwidth = 1;
		constraints.gridheight = 1;
		mainPanel.add(label3,constraints);
		
	  userCombo = new JComboBox();
	  userCombo.setPreferredSize(new Dimension(120, 25));
		userCombo.setEditable(false);
		userCombo.addItem("学生");
		userCombo.addItem("教师");
		userCombo.addItem("管理员");
		userCombo.setSelectedItem("学生");
		selectedItem = (String)userCombo.getSelectedItem();
		constraints.gridx = 2;
		constraints.gridx = 1;
		constraints.gridwidth = 1;
		constraints.gridheight = 1;
		mainPanel.add(userCombo,constraints);
		
		//get selected item, so we can decide to show which frame
		userCombo.addActionListener(new
		  ActionListener()
		  {
		  	public void actionPerformed(ActionEvent e)
		  	{
		      selectedItem = (String)userCombo.getSelectedItem();     //方法别忘了加括号
		    }
		  });
		add(mainPanel, BorderLayout.CENTER);
		
		//add button panel to the frame
		
		JPanel buttonPanel = new JPanel();
	  //add login button
		JButton loginButton = new JButton("确定");
		loginButton.addActionListener(new 
		  ActionListener()
		  {
		  	public void actionPerformed(ActionEvent e)
		  	{
		  		loginDispose();                          //要补充的方法
		  		
	  		  if(login == 1)                                //学要改的
		  		{
  	  		  if(selectedItem.equals("学生"))
		  			{
		  				JFrame f = new StudentsFrame();
		  				f.setVisible(true);
		  				dispose();
		  			}
		  			
		  			else if(selectedItem.equals("教师"))
		  			{
  	  				JFrame f = new TeacherFrame();                   //teacher frame~~
		  				f.setVisible(true);
		  				dispose();
		  			

            }
		  			
		  			
		  			
		  			else if(selectedItem.equals("管理员"))
		  			{
		  				JFrame f = new ManagerFrame();
		  				f.setVisible(true);
		  				dispose();
		  			}
		  		}
		  			
		  		
		  		
		  	}
		  });
		buttonPanel.add(loginButton);
		
		//add cancel button
		JButton cancelButton = new JButton("取消");
		cancelButton.addActionListener(new
		  ActionListener()
		  {
		  	public void actionPerformed(ActionEvent e)
		  	{
		  		System.exit(0);
		  	}
		  });
		buttonPanel.add(cancelButton);
		
		//add about button
		JButton aboutButton = new JButton("关于");
		aboutButton.addActionListener(new
		  ActionListener()
		  {
		  	public void actionPerformed(ActionEvent e)
		  	{
		  		JOptionPane.showMessageDialog(LoginFrame.this, 
		  		                     "        作者：李常友\n指导老师：龙毅宏", 
		  		                              "作品信息",
		  		                              JOptionPane.INFORMATION_MESSAGE,
		  		                              new ImageIcon("01.gif"));
		  		 
		  		 return;
		  	
		  		
		  	}
		  });
		buttonPanel.add(aboutButton);
		
		add(buttonPanel, BorderLayout.SOUTH);
	}
		
   private void loginDispose()              
   {

     	String url = "jdbc:odbc:java"; //数据源名字为java
    	String username = "sa"; 
    	String password = ""; 
    	//加载驱动程序以连接数据库
      	try 
      	{ 
        	Class.forName( "sun.jdbc.odbc.JdbcOdbcDriver" ); 
        	loginConnection = DriverManager.getConnection( url, username, password ); 
      	} 
      	//捕获加载驱动程序异常
      	catch ( ClassNotFoundException cnfex ) 
      	{ 
         	JOptionPane.showMessageDialog (LoginFrame.this ,cnfex ,
              "学生选课管理系统", JOptionPane.WARNING_MESSAGE ); 
         	System.exit( 1 );     // terminate program 
      	} 
      	//捕获连接数据库异常
      	catch ( SQLException sqlex ) 
      	{ 
         	//sqlex.printStackTrace();
         	JOptionPane.showMessageDialog (LoginFrame.this ,"无法连接到SQL SERVER ，\n请确认SQL SERVER是否运行\n或数据源设置是否正确！ " ,
          "学生选课管理系统", JOptionPane.WARNING_MESSAGE );  
         	System.exit( 1 );  // terminate program 
      	} 
     	
     	try
     	{
     		String loginQuery;
     		String loginUserName =  myTextField.getText();             
        String loginPassword = new String(passwordField.getPassword());
        if(myTextField.getText().equals( "" ))
   	      {
   	         JOptionPane.showMessageDialog( LoginFrame.this, "用户名必须为字母、数字和、汉字\n及其组合，不允许为空格键。",
   	                                       "登陆", JOptionPane.WARNING_MESSAGE ); 
                 //setTitle( "无记录显示" ); 
             return; 	
   	      }
        if(selectedItem.equals("教师"))
   			   loginQuery = "SELECT * FROM 教师表 WHERE(登陆帐号='" + loginUserName  + "' AND 登陆密码 ='" + loginPassword + "')";	
   			else if(selectedItem.equals("管理员"))
   			   loginQuery = "SELECT * FROM 管理员 WHERE(用户名='" + loginUserName + "' AND 密码 ='" + loginPassword + "')";			  
   			else //(selectedItem.equals("学生"))
         	   loginQuery = "SELECT * FROM 学生基本信息表 WHERE(学号='" + loginUserName + "' AND 密码 ='" + loginPassword + "')";
   			loginStatement = loginConnection.createStatement(); 
        loginResultSet = loginStatement.executeQuery( loginQuery ); 
        boolean Records = loginResultSet.next();
        if ( ! Records ) 
      	{ 
        		JOptionPane.showMessageDialog(LoginFrame.this, "没有此用户或密码错误" ); 
        		return; 
      	} 
      	else
      	{
      			login = 1 ;	
      	}
      	loginConnection.close();
      }
     	catch(SQLException sqlex)
     	{
     		//sqlex.printStackTrace();
     		JOptionPane.showMessageDialog (LoginFrame.this,sqlex ,
          "学生选课管理系统",JOptionPane.WARNING_MESSAGE ); 
     	}
     	
  }
		
		
		
		
		
		
		

		
		private static final int DEFAULT_WIDTH  = 300;
		private static final int DEFAULT_HEIGHT = 200;
		private GridBagConstraints constraints;
		private JLabel label1, label2, label3;
	  private JPasswordField passwordField;
		private JComboBox userCombo;
		private String selectedItem;
		private int login = 0;
		private Connection loginConnection;
    private Statement loginStatement; 	
    private ResultSet loginResultSet;
    
    public static JTextField myTextField;           //声明登陆名为全局变量!!!!!
    
   
    

}