modcourse.java~28~

自己写的学生选课系统,多多关照.以后共同学习

package student;

import javax.swing.JComboBox;
import java.awt.Rectangle;
import java.sql.*;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import javax.swing.JOptionPane;
import javax.swing.JLabel;
import java.awt.Color;
import java.awt.event.ActionEvent;

public class ModCourse extends CourseInput {
    public ModCourse() {

        try {
            jbInit();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    private void jbInit() throws Exception {
        jComboBoxSearch.setBackground(new Color(136, 136, 226));
        jComboBoxSearch.setBounds(new Rectangle(269, 40, 105, 23));
        jComboBoxSearch.addItemListener(new
                                        ModCourse_jComboBoxSearch_itemAdapter(this));


        String sql = "select Cname from course"; //查询course表里面所包含的课程

        ResultSet rs = DBManager.getResult(sql); //返回结果集

        try {
            while (rs.next()) {
                String str = new String();
                str = rs.getString("Cname"); //取结果集中的元素
                jComboBoxSearch.addItem(str); //添加到jComboBoxSearch
            }

        } catch (Exception ex) {

        }
        this.getContentPane().add(jLabel1);
        this.getContentPane().add(jComboBoxSearch);
        jLabel1.setText("选择你要修改的课程：");
        jLabel1.setBounds(new Rectangle(264, 13, 127, 17));
    }


    JComboBox jComboBoxSearch = new JComboBox();
    JLabel jLabel1 = new JLabel();
    public void jComboBoxSearch_itemStateChanged(ItemEvent e) {

        String sql = " select *  from course where Cname = '" +
                     jComboBoxSearch.getSelectedItem().toString().trim() + "'";
        System.out.println(sql); //在控制台输出sql语句 以便调试
        ResultSet rs = DBManager.getResult(sql);
        try {
            if (rs.next()) {
                jTextFieldNum.setText(rs.getString(1));
                jTextFieldName.setText(rs.getString(2).trim());
                jTextFieldCredit.setText(rs.getString(3));
                jTextFieldSemste.setText(rs.getString(4));
                jTextFieldPeriod.setText(rs.getString(5));
                jTextFieldTeacher.setText(rs.getString(6));

            } else {
                JOptionPane.showMessageDialog(this, "出错！");
            }
        } catch (SQLException ex) {
        }

    }
//重载Course里面的jButton1_actionPerformed（）方法
    public void jButton1_actionPerformed(ActionEvent e) {
        //检查课程号是否为空
        if (jTextFieldNum.getText().trim().equals("")) {
            JOptionPane.showMessageDialog(this, "课程号不能为空");
        }
        //检查课程名是否为空
        if (jTextFieldNum.getText().trim().equals("")) {
            JOptionPane.showMessageDialog(this, "课程名不能为空");
        }
        //修改语句
        String sql =
                "update Course set Cname='"
                + jTextFieldName.getText().trim() + "',"
                + "Ccredit = " +
                Float.parseFloat(jTextFieldCredit.getText().trim()) +
                ","
                + "Semester = " +
                Integer.parseInt(jTextFieldSemste.getText().trim()) +
                ","
                + "Period = " + jTextFieldPeriod.getText().trim() +
                ","
                + "Teacher = '" + jTextFieldTeacher.getText().trim() +
                "' where cno = '" + jTextFieldNum.getText().trim() + "'";

        System.out.println(sql); //在控制台输出sql语句 以便调试

        if (DBManager.executeSql(sql)) {
            JOptionPane.showMessageDialog(this, "课程修改成功！");
        } else {
            JOptionPane.showMessageDialog(this, "课程修改失败！");
        }


    }


}


/***********************下面为监听类*******************************/
class ModCourse_jComboBoxSearch_itemAdapter implements ItemListener {
    private ModCourse adaptee;
    ModCourse_jComboBoxSearch_itemAdapter(ModCourse adaptee) {
        this.adaptee = adaptee;
    }

    public void itemStateChanged(ItemEvent e) {
        adaptee.jComboBoxSearch_itemStateChanged(e);
    }
}