validatenumberservlet.java

数据结构考试 网站（jsp）

package com.dsexam;

import java.io.*;
import java.sql.*;
import java.util.Random;

import javax.sql.*;
import javax.naming.*;
import javax.servlet.*;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class validateNumberServlet extends HttpServlet {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	/**
	 * Constructor of the object.
	 */
	public validateNumberServlet() {
		super();
	}

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	/**
	 * The doGet method of the servlet. <br>
	 * 
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request
	 *            the request send by the client to the server
	 * @param response
	 *            the response send by the server to the client
	 * @throws ServletException
	 *             if an error occurred
	 * @throws IOException
	 *             if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		String strFowardURL;

		String strSNumber = request.getParameter("studentNumber");
		try {
			InitialContext initCtx = new InitialContext();
			DataSource db = (DataSource) initCtx.lookup("java:comp/env/jdbc/dstester");
			Connection conn = db.getConnection();
			Statement stmt = conn.createStatement();
			ResultSet rs = stmt.executeQuery("select * from results where snumber='" + strSNumber + "'");
			if (rs.next()) {
				String topicnumber = rs.getString(2);
				strFowardURL = "/reEnter.jsp?snumber=" + strSNumber
						+ "&topicnumber=" + topicnumber;
			} else {
				ResultSet rs2 = stmt
						.executeQuery("SELECT * FROM student where snumber='"+ strSNumber + "'");
				if (rs2.next()) {
					String password = produceRandom();
					int topicNumber = new Random().nextInt(10) + 1;
					String sql = "insert into results(snumber,password,topicnumber) "
							+ "values('"
							+ strSNumber
							+ "','"
							+ password
							+ "','" + topicNumber + "')";
					stmt.executeUpdate(sql);
					strFowardURL = "/firstEnter.jsp?topicNumber=" + topicNumber
							+ "&password=" + password + "&snumber="
							+ strSNumber + "&topicnumber=" + topicNumber;
				} else
					strFowardURL = "/error.jsp?err_no=1";
				rs2.close();
			}
			rs.close();
			stmt.close();
			conn.close();
			
			ServletContext context = getServletContext();
			RequestDispatcher dispatcher = context.getRequestDispatcher(strFowardURL);
			dispatcher.forward(request, response);
		} catch (Exception e) {
			System.err.println("抛出异常: "+e.getMessage());
		}

	}

	private String produceRandom() {
		// TODO Auto-generated method stub
		String sRand = "";
		for (int i = 0; i < 6; i++) {
			int n = new Random().nextInt(10);
			String rand = String.valueOf(n);
			sRand += rand;
		}
		return sRand;
	}

	/**
	 * The doPost method of the servlet. <br>
	 * 
	 * This method is called when a form has its tag value method equals to
	 * post.
	 * 
	 * @param request
	 *            the request send by the client to the server
	 * @param response
	 *            the response send by the server to the client
	 * @throws ServletException
	 *             if an error occurred
	 * @throws IOException
	 *             if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

	/**
	 * Initialization of the servlet. <br>
	 * 
	 * @throws ServletException
	 *             if an error occurs
	 */
	public void init() throws ServletException {
		// Put your code here
	}

}