choosecourseservlet.java

学生信息管理系统 jsp + sql + javabean 实现

package sms.servlet;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import sms.bean.*;
import sms.db.*;
import java.sql.*;

public class ChooseCourseServlet extends HttpServlet {
    private static final String CONTENT_TYPE = "text/html; charset=GBK";

    //Initialize global variables
    public void init() throws ServletException {
    }

    //Process the HTTP Post request
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws
            ServletException, IOException {
        response.setContentType(CONTENT_TYPE);
        request.setCharacterEncoding("gb2312");
        HttpSession session = request.getSession();
        String courseId = request.getParameter("selectedCourseId");
        System.out.println("test in ChooseCourseServlet courseId:" + courseId);
        String term = request.getParameter("term");
        String week = request.getParameter("week");
        String period = request.getParameter("period");
        System.out.println("test in ChooseCourseServlet term/week/period:" +
                           term + "/" + week + "/" + period);
        if (courseId != null && courseId.length() > 0) {
            System.out.println("test in ChooseCourseServlet 1111111111"); //////////////////
            StudentBean stuBean = null;
            try {
                stuBean = (StudentBean) session.getAttribute(
                        "studentBean");
            } catch (Exception ex1) {
            }
            System.out.println("test in ChooseCourseServlet 222222222"); //////////////////
            if (stuBean == null || stuBean.getStudentId() == null) {
                System.out.println("test in ChooseCourseServlet 33333333"); //////////////////
                RequestDispatcher dispatcher = request.getRequestDispatcher(
                        "/login.jsp");
                dispatcher.forward(request, response);

            } else {
                System.out.println("test in ChooseCourseServlet 444444444"); //////////////////
                String studentId = stuBean.getStudentId();
                System.out.println(
                        "test in ChooseCourseServlet 2 term/week/period:" +
                        term + "/" + week + "/" + period); /////////////////////////
                String sql =
                        "select * from selective_course_scheme where stu_id=" +
                        studentId + " and course_id=" + courseId;
                String sql2 =
                        "insert into selective_course_scheme (stu_id,course_id) values('" +
                        studentId + "','" + courseId + "')";
                DBAccess dba = new DBAccess();
                try {
                    dba.getConnection();
                    ResultSet rs = dba.query(sql);
                    if (rs != null && rs.next()) {
                        dba.closeConnection();
                        String temp = "您已经选择了课程号为：" + courseId + "的课程，不能重复添加！";
                        request.setAttribute("noSelectARowMessege", temp);
                        RequestDispatcher dispatcher = request.
                                getRequestDispatcher(
                                        "/chooseCourse.jsp?forward=true&term=" +
                                        term +
                                        "&week=" + week + "&period=" + period);
                        dispatcher.forward(request, response);
                    }
                    int flag = dba.executeSql(sql2);
                    if (flag > 0) {
                        String temp = String.valueOf(Integer.parseInt(period) *
                                2 - 1) + "-" +
                                      String.valueOf(Integer.parseInt(period) *
                                2);
                        String temp2 = "选课成功，课程号为：" + courseId + "，上课时间：周" +
                                       week + ",第" + temp + "节！";
                        request.setAttribute("noSelectARowMessege", temp2);
                        RequestDispatcher dispatcher = request.
                                getRequestDispatcher(
                                        "/chooseCourse.jsp?forward=true&term=" +
                                        term +
                                        "&week=" + week + "&period=" + period);
                        dispatcher.forward(request, response);
                    } else {
                        request.setAttribute("noSelectARowMessege", "选课失败，请重试！");
                        RequestDispatcher dispatcher = request.
                                getRequestDispatcher(
                                        "/chooseCourse.jsp?forward=true&term=" +
                                        term +
                                        "&week=" + week + "&period=" + period);
                        dispatcher.forward(request, response);
                    }
                } catch (Exception ex) {
                } finally {
                    dba.closeConnection();
                }
            }

        } else {
            request.setAttribute("noSelectARowMessege", "请选择一条记录！");
            RequestDispatcher dispatcher = request.getRequestDispatcher(
                    "/chooseCourse.jsp?forward=true&term=" + term + "&week=" +
                    week + "&period=" + period);
            dispatcher.forward(request, response);
        }
    }

    //Clean up resources
    public void destroy() {
    }
}