一个适合初学者学习的网上教学系统jsp+javascript+javabean+access数据库

package stu; import java.sql.*; public class checkGroup{ String cour_id,stu_id; public void setCour_id(String id){cour_id=id;} public String getCour_id(){return cour_id;} public void setStu_id(String id){stu_id=id;} public String getStu_id(){return stu_id;} public boolean isPre(){ String a=""; boolean ispre =false; String sql="select course.prepare from course where id='"+cour_id+"' "; sqlBean db = new sqlBean(); try{ ResultSet rs =db.executeQuery(sql); if(rs.next()) {a=rs.getString("prepare");} }catch(SQLException ex){ System.err.println("课程号查询有错误:"+ex.getMessage() ); System.out.print("课程号查询有错误:"+ex.getMessage());//输出到客户端 } if(a.equals("0") ) {ispre=false;} else ispre=true; return ispre; } public boolean checkpre(){ boolean f=true; if(isPre()){ String sql="select enrol.class_id "+ "from enrol ,classes,course "+ "where enrol.stu_id='"+stu_id+"' "+ "and course.id='"+cour_id+"' "+ "and course.prepare=classes.cour_id "+ "and enrol.class_id=classes.id "; sqlBean db = new sqlBean(); try{ ResultSet rs = db.executeQuery(sql); if(rs.next()) {f=true;} else f=false;} catch(SQLException ex){ System.err.println("课程号查询有错误:"+ex.getMessage() ); System.out.print("课程号查询有错误:"+ex.getMessage());//输出到客户端 } } return f; } public boolean hasLogin(){ //检查该学生是否已经注册 boolean f=true; String sql="select stu_id,class_id "+ "from enrol,classes "+ "where stu_id='"+stu_id+"' "+ "and classes.id=enrol.class_id "+ "and cour_id='"+cour_id+"' "; sqlBean db =new sqlBean(); try{ ResultSet rs=db.executeQuery(sql); if(rs.next()){ f=false;} else{ f=true;} }catch(Exception e){ e.getMessage();} return f; } public String getClassid(){ String class_id=null; if(checkpre()){ String sql="select classes.id from classes where cour_id='"+cour_id+"' "; sqlBean db = new sqlBean(); ResultSet rs = db.executeQuery(sql); try{ if(rs.next()){class_id=rs.getString("id"); } }catch(SQLException ex){ System.err.println("课程号查询有错误:"+ex.getMessage() ); System.out.print("课程号查询有错误:"+ex.getMessage());//输出到客户端 } } else {class_id="error";} return class_id; } public String getTime(){ String class_id=getClassid(); String time=""; if(checkpre()){ String sql="select cour_time from classes where cour_id='"+cour_id+"'"; sqlBean db = new sqlBean(); ResultSet rs = db.executeQuery(sql); try{ if(rs.next()) { time=rs.getString("cour_time");} }catch(SQLException ex){ System.err.println("查询有错误:"+ex.getMessage() ); System.out.print("查询有错误:"+ex.getMessage());//输出到客户端 } } else{time="error";} return time; } public String getClassRoom(){ String class_id=getClassid(); String room=""; if(checkpre()){ String sql="select room_id from classes where cour_id='"+cour_id+"'"; sqlBean db = new sqlBean(); ResultSet rs = db.executeQuery(sql); try{ if(rs.next()) { room=rs.getString("room_id");} }catch(SQLException ex){ System.err.println("课程号查询有错误:"+ex.getMessage() ); System.out.print("课程号查询有错误:"+ex.getMessage());//输出到客户端 } } else {room="error";} return room; } public void enrol(){ String class_id=null; if(checkpre()){ try{ String sql="select classes.id from classes where cour_id='"+cour_id+"' "; sqlBean db = new sqlBean(); ResultSet rs = db.executeQuery(sql); if(rs.next()){class_id=rs.getString("id"); } } catch(SQLException ex){ System.err.println("课程号查询有错误:"+ex.getMessage() ); System.out.print("课程号查询有错误:"+ex.getMessage());//输出到客户端 } String sql="insert into enrol(stu_id,class_id,accept) "+ " VALUES('"+stu_id+"','"+class_id+"','0') "; sqlBean db = new sqlBean(); db.executeInsert(sql); } } }