servletanswer.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 Servletanswer extends javax.servlet.http.HttpServlet implements
		javax.servlet.Servlet {
	public void doGet(HttpServletRequest req, HttpServletResponse res)
			throws ServletException, IOException {
		int id = 0, ask_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();
			ask_id = Integer.valueOf(req.getParameter("ask_id")).intValue();
		} catch (NumberFormatException e) {
		}
		AnswerBean answers = null;

		if (sort != null) {
			if ("new".equalsIgnoreCase(action)) {

				answers = doNew(req, res);

				sendBean(req, res, answers, "/answer.jsp?ask_id=" + id);
			}

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

					sendBean(req, res, answers, "/answer.jsp?ask_id=" + ask_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("answer.jsp?ask_id=" + ask_id);
				}
			}
		} else
			doError(req, res, "你无权操作，或你还没有登陆！");
	}

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

		AnswerBean answers = new AnswerBean();
		String sort = new String(req.getParameter("sort").getBytes("ISO8859_1"));
		String content = new String(req.getParameter("content").getBytes(
				"ISO8859_1"));
		String time = new String(req.getParameter("time").getBytes("ISO8859_1"));
		int ans_id = 0, id = 0;
		try {
			ans_id = Integer.valueOf(req.getParameter("ans_id")).intValue();
			id = Integer.valueOf(req.getParameter("id")).intValue();

		} catch (NumberFormatException e) {
		}
		answers.setSort(sort);
		answers.setContent(content);
		answers.setTime(time);
		answers.setAns_id(ans_id);
		answers.setAsk_id(id);

		answers.addAnswer();
		return answers;
	}

	public AnswerBean doUpdate(HttpServletRequest req, HttpServletResponse res,
			int id) throws ServletException, IOException, SQLException {
		AnswerBean answers = new AnswerBean();

		String content = new String(req.getParameter("content").getBytes(
				"ISO8859_1"));
		String time = new String(req.getParameter("time").getBytes("ISO8859_1"));

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

			answers.setContent(content);
			answers.setTime(time);

			answers.updateAnswer(id);
		}
		return answers;
	}

	public int doDelete(int id) throws SQLException {
		int num = 0;
		AnswerBean answers = new AnswerBean();
		num = answers.deleteAnswer(id);
		return num;
	}

	public void sendBean(HttpServletRequest req, HttpServletResponse res,
			AnswerBean answers, String target) throws ServletException,
			IOException {
		req.setAttribute("answers", answers);
		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 content) throws ServletException, IOException {
		boolean f = true;
		String 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);
	}
}