servletask.java

在线教育平台： 从小学

package edu;

import java.io.IOException;
import java.sql.SQLException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class Servletask extends javax.servlet.http.HttpServlet implements
		javax.servlet.Servlet {
	public void doGet(HttpServletRequest req, HttpServletResponse res)
			throws ServletException, IOException {
		int id = 0;
		int success = 0;
		HttpSession session = req.getSession(true);
		String sort = null;
		try {
			sort = session.getAttribute("sort").toString();
		} catch (NullPointerException e) {
		}
		String action = null;
		action = req.getParameter("action");
		try {
			id = Integer.valueOf(req.getParameter("id")).intValue();
		} catch (NumberFormatException e) {
		}
		AskBean asks = null;

		if (sort != null) {
			if ("new".equalsIgnoreCase(action)) {
				asks = doNew(req, res);

			}

			if ("update".equalsIgnoreCase(action)) {
				try {
					asks = doUpdate(req, res, id);

					sendBean(req, res, asks, "answer.jsp?ask_id=" + id);
				} catch (SQLException e) {
				}
			}

			if ("delete".equalsIgnoreCase(action)) {

				if (sort.equals("admin")) {
					try {
						success = doDelete(id);
					} catch (SQLException e) {
					}
				} else
					doError(req, res, "你无权操作，或你还没有登陆！");

				if (success != 1) {
					doError(req, res, "删除失败. Rows affected: " + success);
				} else {
					res.sendRedirect("index.jsp");
				}
			}
		} else
			doError(req, res, "你无权操作，或你还没有登陆！");

	}

	public AskBean doNew(HttpServletRequest req, HttpServletResponse res)
			throws ServletException, IOException {

		AskBean asks = new AskBean();
		String title = new String(req.getParameter("title").getBytes(
				"ISO8859_1"));
		String content = new String(req.getParameter("content").getBytes(
				"ISO8859_1"));
		String time = new String(req.getParameter("time").getBytes("ISO8859_1"));
		String sort = new String(req.getParameter("sort").getBytes("ISO8859_1"));
		int grade_id = 0, class_id = 0, u_id = 0, answer_id = 0, subject_id = 0;
		try {
			u_id = Integer.valueOf(req.getParameter("u_id")).intValue();
			answer_id = Integer.valueOf(req.getParameter("answer_id"))
					.intValue();
			subject_id = Integer.valueOf(req.getParameter("subject_id"))
					.intValue();
			class_id = Integer.valueOf(req.getParameter("class_id")).intValue();
			grade_id = Integer.valueOf(req.getParameter("grade_id")).intValue();
		} catch (NumberFormatException e) {
		}
		try {
			asks.setSort(sort);
			asks.setTitle(title);
			asks.setContent(content);
			asks.setTime(time);
			asks.setU_id(u_id);
			asks.setAnswer_id(answer_id);
			asks.setClass_id(class_id);
			asks.setGrade_id(grade_id);
			asks.setSubject_id(subject_id);
			asks.addAsk();
			res.sendRedirect("asklist.jsp?grade_id=" + grade_id + "&class_id="
					+ class_id + "&subject_id=" + subject_id);
		} catch (NullPointerException e) {
		}
		return asks;
	}

	public AskBean doUpdate(HttpServletRequest req, HttpServletResponse res,
			int id) throws ServletException, IOException, SQLException {
		AskBean asks = new AskBean();
		String title = new String(req.getParameter("title").getBytes(
				"ISO8859_1"));
		String content = new String(req.getParameter("content").getBytes(
				"ISO8859_1"));
		String time = new String(req.getParameter("time").getBytes("ISO8859_1"));
		// int u_id=0;
		// try{
		// u_id=Integer.valueOf(req.getParameter("u_id")).intValue();
		//
		// }catch(NumberFormatException e){}

		if (isTrue(req, res, title, content)) {

			asks.setTitle(title);
			asks.setContent(content);
			asks.setTime(time);
			// asks.setU_id(u_id);

			asks.updateAsk(id);
		}
		return asks;
	}

	public int doDelete(int id) throws SQLException {
		int num = 0;
		AskBean asks = new AskBean();
		num = asks.deleteAsk(id);
		return num;
	}

	public void sendBean(HttpServletRequest req, HttpServletResponse res,
			AskBean asks, String target) throws ServletException, IOException {
		req.setAttribute("asks", asks);
		try {
			RequestDispatcher rd = req.getRequestDispatcher(target);
			rd.forward(req, res);
		} catch (Throwable t) {
		}
	}

	public void doError(HttpServletRequest req, HttpServletResponse res,
			String str) throws ServletException, IOException {
		req.setAttribute("problem", str);
		try {
			RequestDispatcher rd = req.getRequestDispatcher("/errorpage.jsp");
			rd.forward(req, res);
		} catch (Throwable t) {
		}
	}

	public boolean isTrue(HttpServletRequest req, HttpServletResponse res,
			String title, String content) throws ServletException, IOException {
		boolean f = true;
		String message = "";
		if (title == null || title.equals("")) {
			f = false;
			message = "主题不能为空，请重新填写！";
			doError(req, res, message);
		}
		if (content == null || content.equals("")) {
			f = false;
			message = "内容不能为空，请重新填写！";
			doError(req, res, message);
		}
		return f;
	}

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