teachersvlt.java

一个学生课绩管理系统

package control;

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

import database.teacher;

public class TeacherSvlt extends HttpServlet {

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

		String tea_id = req.getParameter("id");
		int success = 0;
		String action = action = req.getParameter("action");
		teacher tea = null;
		String message = "";

		if ("new".equalsIgnoreCase(action)) {
			tea = doNew(req, res);

			sendBean(req, res, tea, "/getteacher.jsp");
		}

		if ("update".equalsIgnoreCase(action)) {
			try {
				tea = doUpdate(req, res, tea_id);
				sendBean(req, res, tea, "/getteacher.jsp");
			} catch (SQLException e) {
			}
		}

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

	public teacher doNew(HttpServletRequest req, HttpServletResponse res)
			throws ServletException, IOException {
		teacher tea = new teacher();
		String tea_id = req.getParameter("id");
		String name = new String(req.getParameter("name").getBytes("ISO8859_1"));
		String password = req.getParameter("password");
		String title = new String(req.getParameter("title").getBytes(
				"ISO8859_1"));

		if (isTrue(req, res, tea_id, name, password)
				&& hasLogin(req, res, tea_id)) {

			tea.setId(tea_id);
			tea.setName(name);
			tea.setPassword(password);
			tea.setTitle(title);
			tea.addTeacher();
		}
		return tea;

	}

	public teacher doUpdate(HttpServletRequest req, HttpServletResponse res,
			String id) throws ServletException, IOException, SQLException {
		teacher tea = new teacher();

		String name = new String(req.getParameter("name").getBytes("ISO8859_1"));
		String password = req.getParameter("password");
		String title = new String(req.getParameter("title").getBytes(
				"ISO8859_1"));
		if (isTrue(req, res, id, name, password)) {
			tea.setId(id);
			tea.setName(name);
			tea.setPassword(password);
			tea.setTitle(title);
			tea.update();
		}
		return tea;
	}

	public int doDelete(String id) throws SQLException {
		int num = 0;
		teacher tea = new teacher();
		num = tea.delete(id);
		return num;
	}

	public void sendBean(HttpServletRequest req, HttpServletResponse res,
			teacher tea, String target) throws ServletException, IOException {
		req.setAttribute("tea", tea);
		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，该教师号已经被注册过了!";
		teacher tea = new teacher();
		f = tea.hasLogin(id);
		if (f == false) {
			doError(req, res, message);
		}
		return f;
	}

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

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

		if (password == null || password.equals("")) {
			f = false;
			message = "密码不能为空，请重新填写！";
			doError(req, res, message);
		}
		return f;
	}

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

}