itemdao.java

只做是单选题！数据库表有三张：EUser,EItem,Score

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package com.exam.model;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.sql.DataSource;

/**
 *
 * @author Administrator
 */
public class ItemDAO {

    private static final String GET_EXAM = "SELECT * FROM EITEM ";
    private String GET_ANSWER = "SELECT answer FROM EITEM WHERE  QID =? ";
    private DataSource datasource;

    public ItemDAO() {
        try {
            Context ctx = new InitialContext();
            datasource = (DataSource) ctx.lookup("jdbc/examDB");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public List getExam() {
        List exam = new ArrayList();
        Connection con = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            con = datasource.getConnection();
            ps = con.prepareStatement(GET_EXAM);
            rs = ps.executeQuery();
            while (rs.next()) {
                Item item = new Item(rs.getInt("QID"), rs.getString("question"), rs.getString("option_a"),
                        rs.getString("option_b"), rs.getString("option_c"), rs.getString("option_d"), rs.getString("answer"));
                exam.add(item);
            }
        } catch (SQLException se) {
            se.printStackTrace();
        } finally {
            if (rs != null) {
                try {
                    rs.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            if (ps != null) {
                try {
                    ps.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            if (con != null) {
                try {
                    con.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
        return exam;
    }

    public String getAnswer(int QID) {
        String answer = null;
        Connection con = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            con = datasource.getConnection();
            ps = con.prepareStatement(GET_ANSWER);
            ps.setInt(1, QID);
            rs = ps.executeQuery();
            while (rs.next()) {
                answer = rs.getString("answer");
            }
        } catch (SQLException se) {
            se.printStackTrace();
        } finally {
            if (rs != null) {
                try {
                    rs.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            if (ps != null) {
                try {
                    ps.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            if (con != null) {
                try {
                    con.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
        return answer;
    }
}