在线模拟考试系统

/* * This product includes software developed by the * Apache Software Foundation (http://www.apache.org/). */ package ch07.database; import java.sql.Connection; import java.sql.ResultSet; import java.sql.Statement; import java.util.*; import javax.servlet.http.HttpSession; import ch07.*; import ch07.object.unit.*; /** * 针对问题信息的数据处理类 * @author ShenYK * @version 1.0 */ public class DQuestion extends DCommon { //随机获得该分类指定数目的题目 public Vector getRandomQuestions( String sUsername, String sCategoryId, int iNumber ) throws Exception { //获得数据库连接 Connection conn = this.getDBConnection(); if ( conn == null ) { throw new Exception("数据库连接获得失败！"); } Statement stmt = null; ResultSet rs = null; try { Vector vQuestions = new Vector(); stmt = conn.createStatement(); //执行SQL语句，找出所有可用的题目ID String sQuery = "select * from question where category_id='" + sCategoryId + "' order by rand() limit 0," + iNumber; rs = stmt.executeQuery( sQuery ); while ( rs.next() ) { Question objQuestion = new Question(rs); vQuestions.add( objQuestion ); } return vQuestions; } catch(Exception e) { e.printStackTrace(); throw e; } finally { try { rs.close(); stmt.close(); conn.close(); }catch(Exception ex) { } } } //获得指定分类的题目 public Vector getAllQuestionsByCategoryId( String sCategoryId ) throws Exception { //获得数据库连接 Connection conn = this.getDBConnection(); if ( conn == null ) { throw new Exception("数据库连接获得失败！"); } Statement stmt = null; ResultSet rs = null; try { Vector vQuestions = new Vector(); stmt = conn.createStatement(); //执行SQL语句，找出所有可用的题目ID String sQuery = "select * from question where category_id='" + sCategoryId + "' order by question_id"; rs = stmt.executeQuery( sQuery ); while ( rs.next() ) { Question objQuestion = new Question(rs); vQuestions.add( objQuestion ); } return vQuestions; } catch(Exception e) { e.printStackTrace(); throw e; } finally { try { rs.close(); stmt.close(); conn.close(); }catch(Exception ex) { } } } //删除指定的题目 public void deleteQuestionById( String sQuestionId ) throws Exception { //获得数据库连接 Connection conn = this.getDBConnection(); if ( conn == null ) { throw new Exception("数据库连接获得失败！"); } Statement stmt = null; try { stmt = conn.createStatement(); //执行SQL语句，删除ID String sUpdateQuery = "delete from question where question_id='" + sQuestionId + "'"; stmt.executeUpdate( sUpdateQuery ); return; } catch(Exception e) { e.printStackTrace(); throw e; } finally { try { stmt.close(); conn.close(); }catch(Exception ex) { } } } //获得指定ID的题目详细信息 public Question getQuestionById( String sQuestionId ) throws Exception { //获得数据库连接 Connection conn = this.getDBConnection(); if ( conn == null ) { throw new Exception("数据库连接获得失败！"); } Statement stmt = null; ResultSet rs = null; try { stmt = conn.createStatement(); //执行SQL语句，找出所有可用的题目ID String sQuery = "select * from question where question_id='" + sQuestionId + "'"; rs = stmt.executeQuery( sQuery ); if ( rs.next() ) { Question objQuestion = new Question(rs); return objQuestion; } return null; } catch(Exception e) { e.printStackTrace(); throw e; } finally { try { rs.close(); stmt.close(); conn.close(); }catch(Exception ex) { } } } //修改指定的题目 public void modifyQuestion ( Question questionObj ) throws Exception { //获得数据库连接 Connection conn = this.getDBConnection(); if ( conn == null ) { throw new Exception("数据库连接获得失败！"); } Statement stmt = null; try { stmt = conn.createStatement(); //执行SQL语句，修改题目 String sUpdateQuery = "update question set " + "subject = '" + questionObj.getSubject() + "', " + "choice_a = '" + questionObj.getChoiceA() + "', " + "choice_b = '" + questionObj.getChoiceB() + "', " + "choice_c = '" + questionObj.getChoiceC() + "', " + "choice_d = '" + questionObj.getChoiceD() + "', " + "answer = '" + questionObj.getAnswer() + "' " + "where question_id = '" + questionObj.getQuestionId() + "'"; stmt.executeUpdate( sUpdateQuery ); return; } catch(Exception e) { e.printStackTrace(); throw e; } finally { try { stmt.close(); conn.close(); }catch(Exception ex) { } } } //添加一个新试题 public void addQuestion ( Question questionObj ) throws Exception { //获得数据库连接 Connection conn = this.getDBConnection(); if ( conn == null ) { throw new Exception("数据库连接获得失败！"); } Statement stmt = null; ResultSet rs = null; try { stmt = conn.createStatement(); //执行SQL语句生成最大的recordId String sQuestionId = ""; String sQuery = "select max(question_id) from question"; rs = stmt.executeQuery( sQuery ); rs.next(); String sCurrentMaxId = rs.getString(1); //当前是第一次登录 if ( sCurrentMaxId == null ) { sQuestionId = "0000000001"; } else { int iMaxCd = Integer.parseInt(sCurrentMaxId); sQuestionId = String.valueOf(iMaxCd+1); int iLength = sQuestionId.length(); for(int i=10; i>iLength; i--) { sQuestionId = "0" + sQuestionId; } } //执行SQL语句，修改题目 Strin