coursesvlt.java

一个学生课绩管理系统

package control;

import java.io.*;
import java.sql.*;
import database.course;
import javax.servlet.*;
import javax.servlet.http.*;

public class CourseSvlt extends HttpServlet {

	public void doGet(HttpServletRequest req, HttpServletResponse res)
			throws ServletException, IOException {
		String cour_id = req.getParameter("id");
		int success = 0;
		String action = action = req.getParameter("action");
		course cour = null;
		String message = "";

		if ("new".equalsIgnoreCase(action)) {
			cour = doNew(req, res);
			sendBean(req, res, cour, "/getcourse.jsp");
		}

		if ("update".equalsIgnoreCase(action)) {
			try {
				cour = doUpdate(req, res, cour_id);
				sendBean(req, res, cour, "/getcourse.jsp");
			} catch (SQLException e) {
				System.out.println(e);
			}
		}

		if ("delete".equalsIgnoreCase(action)) {
			try {
				success = doDelete(cour_id);
			} catch (SQLException e) {
			}
			if (success != 1) {
				doError(req, res,
						"CourseSvlt: Delete unsuccessful. Rows affected: "
								+ success);
			} else {
				res.sendRedirect("http://localhost:8080/test/getcourse.jsp");
			}
		}
	}

	public course doNew(HttpServletRequest req, HttpServletResponse res)
			throws ServletException, IOException {
		course cour = new course();
		String cour_id = req.getParameter("id");
		int mark;
		String name = new String(req.getParameter("name").getBytes("ISO8859_1"));
		try {
			mark = Integer.parseInt(req.getParameter("mark"));
		} catch (NumberFormatException e) {
			mark = 0;
		}
		String dep = new String(req.getParameter("dep").getBytes("ISO8859_1"));
		String prepare = req.getParameter("prepare");
		if (isTrue(req, res, cour_id, name) && hasLogin(req, res, cour_id)
				&& isCompare(prepare, dep, req, res)) {

			cour.setId(cour_id);
			cour.setName(name);
			cour.setDep(dep);
			cour.setPrepare(prepare);
			cour.setMark(mark);
			cour.addCourse();
		}
		return cour;
	}

	public boolean isCompare(String prepare, String dep,
			HttpServletRequest req, HttpServletResponse res)
			throws ServletException, IOException {
		boolean f = true;
		String tempDep = null;
		String message = null;
		course cour = new course();
		if (!prepare.equalsIgnoreCase("0")) {
			tempDep = cour.getPrepareDep(prepare);
			if (tempDep.equals("public"))
				return true;
			if (dep.equalsIgnoreCase(tempDep))
				f = true;
			else {
				f = false;
				message = "错误，课程所在系与预修课所在系不一致！";
				doError(req, res, message);
			}
		}
		return f;
	}

	public course doUpdate(HttpServletRequest req, HttpServletResponse res,
			String id) throws ServletException, IOException, SQLException {
		course cour = new course();
		String name = new String(req.getParameter("name").getBytes("ISO8859_1"));
		int mark = Integer.parseInt(req.getParameter("mark"));

		String dep = req.getParameter("dep");
		String prepare = req.getParameter("prepare");

		if (isTrue(req, res, id, name) && isCompare(prepare, dep, req, res)) {

			cour.setName(name);
			cour.setMark(mark);
			cour.setDep(dep);
			cour.setPrepare(prepare);

			cour.updateCourse(id);
		}
		return cour;
	}

	public int doDelete(String id) throws SQLException {
		int num = 0;
		course cour = new course();
		num = cour.deleteCourse(id);
		return num;
	}

	public void sendBean(HttpServletRequest req, HttpServletResponse res,
			course cour, String target) throws ServletException, IOException {
		req.setAttribute("cour", cour);
		RequestDispatcher rd = getServletContext().getRequestDispatcher(target);
		rd.forward(req, res);
	}

	public void doError(HttpServletRequest req, HttpServletResponse res,
			String str) throws ServletException, IOException {

		req.setAttribute("problem", str);
		RequestDispatcher rd = getServletContext().getRequestDispatcher(
				"/errorpage.jsp");
		rd.forward(req, res);
	}

	public boolean hasLogin(HttpServletRequest req, HttpServletResponse res,
			String id) throws ServletException, IOException {
		boolean f = true;
		String message = "对不起，该课程号已经被注册过了!";
		course cour = new course();
		f = cour.hasLogin(id);
		if (f == false) {
			doError(req, res, message);
		}
		return f;
	}

	public boolean isTrue(HttpServletRequest req, HttpServletResponse res,
			String id, String name) throws ServletException, IOException {
		boolean f = true;
		String message = "";
		if (id == null || id.equals("")) {
			f = false;
			message = "错误，课程号不能为空！";
			doError(req, res, message);
		}

		if (name == null || name.equals("")) {
			f = false;
			message = "课程名不能为空，请重新填写！";
			doError(req, res, message);
		}

		return f;

	}

	public void doPost(HttpServletRequest req, HttpServletResponse res)
			throws ServletException, IOException {

		doGet(req, res);

	}

}