courseservlet.java

学生成绩管理系统JPA做的

package com.fengmanfei.student.servlet;

import java.io.IOException;
import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import javax.persistence.Query;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.fengmanfei.student.entity.CourseEO;
import com.fengmanfei.student.entity.StudentEO;
import com.fengmanfei.student.exception.StudentException;

public class CourseServlet extends HttpServlet {

	private static final long serialVersionUID = -6374362036750447977L;

	EntityManagerFactory emf;

	@Override
	public void init() throws ServletException {
		emf = Persistence.createEntityManagerFactory("student");
	}

	@SuppressWarnings("unchecked")
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		EntityManager em = emf.createEntityManager();

		String action = request.getParameter("action");

		try {

			if ("list".equals(action)) {

				List<CourseEO> courseList = em.createQuery(" from CourseEO ")
						.getResultList();

				request.setAttribute("courseList", courseList);
				request.getRequestDispatcher("/listCourse.jsp").forward(
						request, response);

			} else if ("add".equals(action)) {

				String name = request.getParameter("name");
				String teacher = request.getParameter("teacher");
				String description = request.getParameter("description");

				boolean optional = "true".equals(request
						.getParameter("optional"));

				EntityTransaction trans = em.getTransaction();

				trans.begin();

				Query query = em.createQuery(
						" from CourseEO where name = :name ").setParameter(
						"name", name);

				if (query.getResultList().size() > 0) {
					throw new StudentException("已经存在课程《" + name + "》。 ");
				}

				CourseEO courseEO = new CourseEO();
				courseEO.setName(name);
				courseEO.setOptional(optional);
				courseEO.setTeacher(teacher);
				courseEO.setDescription(description);

				em.persist(courseEO);

				trans.commit();

				request.setAttribute("msg", "课程《" + courseEO.getName()
						+ "》添加成功。");

				request.setAttribute("courseEO", courseEO);
				request.getRequestDispatcher("/addCourseSuccess.jsp").forward(
						request, response);

			} else if ("edit".equals(action)) {

				int courseId = Integer.parseInt(request
						.getParameter("courseId"));

				CourseEO courseEO = em.find(CourseEO.class, courseId);

				request.setAttribute("courseEO", courseEO);
				request.getRequestDispatcher("/addCourse.jsp").forward(request,
						response);

			} else if ("save".equals(action)) {

				int id = Integer.parseInt(request.getParameter("courseId"));

				String name = request.getParameter("name");
				String teacher = request.getParameter("teacher");
				String description = request.getParameter("description");

				boolean optional = "true".equals(request
						.getParameter("optional"));

				EntityTransaction trans = em.getTransaction();

				trans.begin();

				Query query = em.createQuery(
						" from CourseEO where name = :name and id != :id ")
						.setParameter("name", name).setParameter("id", id);

				if (query.getResultList().size() > 0) {
					throw new StudentException("已经存在课程《" + name + "》。 ");
				}

				CourseEO courseEO = em.find(CourseEO.class, id);
				courseEO.setName(name);
				courseEO.setOptional(optional);
				courseEO.setTeacher(teacher);
				courseEO.setDescription(description);

				em.persist(courseEO);

				request.setAttribute("msg", "课程《" + courseEO.getName()
						+ "》修改成功");

				request.setAttribute("courseEO", courseEO);
				request.getRequestDispatcher("/addCourseSuccess.jsp").forward(
						request, response);

				trans.commit();

			} else if ("delete".equals(action)) {

				int courseId = Integer.parseInt(request
						.getParameter("courseId"));

				EntityTransaction trans = em.getTransaction();

				trans.begin();

				CourseEO courseEO = em.find(CourseEO.class, courseId);

				List<StudentEO> studentList = em.createQuery(
						" SELECT s FROM StudentEO s, IN(s.courses) c "
								+ " WHERE c.id = :courseId ").setParameter(
						"courseId", courseId).getResultList();

				if (studentList.size() > 0) {
					throw new StudentException("不能删除课程《" + courseEO.getName()
							+ "》。共有 " + studentList.size() + " 个同学选定了该课程。");
				}

				em.remove(courseEO);

				trans.commit();

				request.setAttribute("msg", "课程《" + courseEO.getName()
						+ "》删除成功");

				request.getRequestDispatcher("/addCourseSuccess.jsp").forward(
						request, response);

			} else if ("initAddStudentCourse".equals(action)) {

				int courseId = Integer.parseInt(request
						.getParameter("courseId"));

				CourseEO courseEO = em.find(CourseEO.class, courseId);

				List<StudentEO> studentList = em
						.createQuery(" from StudentEO ").getResultList();

				request.setAttribute("courseEO", courseEO);
				request.setAttribute("studentList", studentList);

				request.getRequestDispatcher("/addStudentCourse.jsp").forward(
						request, response);

			} else if ("saveStudentCourse".equals(action)) {

				int courseId = Integer.parseInt(request
						.getParameter("courseId"));

				String[] studentId = request.getParameterValues("studentId");

				EntityTransaction trans = em.getTransaction();

				trans.begin();

				CourseEO courseEO = em.find(CourseEO.class, courseId);

				em
						.createNativeQuery(
								" delete from tb_student_course where course_id = :courseId ")
						.setParameter("courseId", courseId).executeUpdate();

				for (int i = 0; studentId != null && i < studentId.length; i++) {

					int id = Integer.parseInt(studentId[i]);

					StudentEO studentEO = em.find(StudentEO.class, id);

					studentEO.getCourses().add(courseEO);

					em.merge(studentEO);
				}

				List<StudentEO> studentList = em
						.createQuery(" from StudentEO ").getResultList();

				trans.commit();

				request.setAttribute("msg", "学生选课修改成功。");

				request.setAttribute("courseEO", courseEO);
				request.setAttribute("studentList", studentList);

				request.getRequestDispatcher("/addCourseSuccess.jsp").forward(
						request, response);

			}

		} finally {
			em.close();
		}

	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doGet(request, response);
	}

	@Override
	public void destroy() {
		emf.close();
	}

}