选课.java

经过调查分析

/*
 * Xuanke1.java
 *
 * Created on 2008年11月20日, 下午8:25
 */

package javaapplication1;
import java.sql.*;
import java.util.*;
import java.awt.*;
import javax.swing.*;
/**
 *
 * @author  mis06
 */
public class 选课 extends javax.swing.JPanel {
    
    /** Creates new form Xuanke1 */
    public 选课() {
        initComponents();
    }
    
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    // <editor-fold defaultstate="collapsed" desc=" Generated Code ">//GEN-BEGIN:initComponents
    private void initComponents() {
        jLabel1 = new javax.swing.JLabel();
        jTextField1 = new javax.swing.JTextField();
        jButton1 = new javax.swing.JButton();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();
        jButton2 = new javax.swing.JButton();
        jLabel2 = new javax.swing.JLabel();
        jButton3 = new javax.swing.JButton();
        jScrollPane2 = new javax.swing.JScrollPane();
        jTextArea2 = new javax.swing.JTextArea();

        jLabel1.setText("\u8bfe\u7a0b\u53f7");

        jButton1.setText("\u9009\u4fee");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jTextArea1.setColumns(20);
        jTextArea1.setEditable(false);
        jTextArea1.setRows(5);
        jScrollPane1.setViewportView(jTextArea1);

        jButton2.setText("\u5220\u9664");
        jButton2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton2ActionPerformed(evt);
            }
        });

        jLabel2.setText("\u67e5\u770b\u5f00\u8bbe\u9009\u4fee\u8bfe\u7a0b");

        jButton3.setText("\u67e5\u770b");
        jButton3.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton3ActionPerformed(evt);
            }
        });

        jTextArea2.setColumns(20);
        jTextArea2.setEditable(false);
        jTextArea2.setRows(5);
        jScrollPane2.setViewportView(jTextArea2);

        org.jdesktop.layout.GroupLayout layout = new org.jdesktop.layout.GroupLayout(this);
        this.setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(layout.createSequentialGroup()
                .addContainerGap()
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.TRAILING)
                    .add(org.jdesktop.layout.GroupLayout.LEADING, jScrollPane1, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 404, Short.MAX_VALUE)
                    .add(org.jdesktop.layout.GroupLayout.LEADING, layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING, false)
                        .add(layout.createSequentialGroup()
                            .add(jLabel1)
                            .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED)
                            .add(jTextField1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 97, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                            .add(39, 39, 39)
                            .add(jButton1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 74, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                            .add(55, 55, 55)
                            .add(jButton2, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 74, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))
                        .add(layout.createSequentialGroup()
                            .add(jLabel2)
                            .add(19, 19, 19)
                            .add(jButton3))
                        .add(jScrollPane2, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 404, Short.MAX_VALUE)))
                .add(266, 266, 266))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(layout.createSequentialGroup()
                .addContainerGap()
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE)
                    .add(jLabel2)
                    .add(jButton3, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 23, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))
                .add(14, 14, 14)
                .add(jScrollPane2, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 179, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                .add(33, 33, 33)
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE)
                    .add(jLabel1)
                    .add(jButton1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 32, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                    .add(jButton2, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 31, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                    .add(jTextField1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 28, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))
                .add(15, 15, 15)
                .add(jScrollPane1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 78, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                .add(168, 168, 168))
        );
    }// </editor-fold>//GEN-END:initComponents

    private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_jButton3ActionPerformed
   
        Statement statement;
        try{
                Connect con=new Connect();
                statement=con.con.createStatement();
                StringBuffer results=new StringBuffer();
                
                
                String sql="SELECT * FROM 课程 WHERE 选课属性='选修'";
                
                ResultSet resultSet0=statement.executeQuery(sql);
                ResultSetMetaData metaData0=resultSet0.getMetaData();
                int numberOfColumns0=metaData0.getColumnCount();
                
                
                for(int i=1;i<=numberOfColumns0;i++)
                    results.append(metaData0.getColumnName(i)+"\t");
                
                results.append("\n");
                
                while(resultSet0.next()){
                    for(int i=1;i<=numberOfColumns0;i++)
                         results.append(resultSet0.getObject(i)+"\t");
                     results.append("\n");
                     }
                
                jTextArea2.setText(results.toString());
                   jTextArea2.setEditable(false);
                
        }
        catch(SQLException sqlException){
        JOptionPane.showMessageDialog(null,sqlException.getMessage(),"Database Error",JOptionPane.ERROR_MESSAGE);
        System.exit(1);}

       catch(ClassNotFoundException classNotFound){
       JOptionPane.showMessageDialog(null,classNotFound.getMessage(),"Driver Not Found",JOptionPane.ERROR_MESSAGE);
        System.exit(1); }
    // TODO add your handling code here:
    }//GEN-LAST:event_jButton3ActionPerformed

    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_jButton2ActionPerformed
   
        Statement statement;
        String number=new String(jTextField1.getText());
        try{
                Connect con=new Connect();
                statement=con.con.createStatement();
                
                int flag=0;
                 String str,studentNumber = null;
                
                str="SELECT 编号 FROM 用户 WHERE 状态='登录'";
                
                ResultSet resultSet1=statement.executeQuery(str);
                ResultSetMetaData metaData1=resultSet1.getMetaData();
                int numberOfColumns1=metaData1.getColumnCount();
                
                while(resultSet1.next()){
                    for(int i=1;i<=numberOfColumns1;i++)
                        studentNumber=resultSet1.getObject(i).toString();
                     }
                
                String courseNumber=null;
                String sql="select 课程号 from 成绩 where 学号='"+studentNumber+"'";
                
                ResultSet resultSet=statement.executeQuery(sql);
                ResultSetMetaData metaData=resultSet.getMetaData();
                int numberOfColumns=metaData.getColumnCount();
                
                while(resultSet.next()){
                    for(int i=1;i<=numberOfColumns;i++)
                        courseNumber=resultSet.getObject(i).toString();
                    if(courseNumber.equals(number))
                        flag++;
                    courseNumber=null;
                     }