v1.0
	* ʵģתɴ
	
v1.1
	* װݿConnection
	* CourseManagerʵӿγ̷	
	* õģʽȡCourseManager 
	
V1.2
	* CourseController,ɿγ
	
v1.3
	* ѯγб
	
v1.4
	* ɾγ̺޸Ŀγ̷		
	
v1.5
	* õݹȡ༶Ϣ 	
	
v1.6
	* Ӱ༶
	* عDbUtil	
		
v1.7
	* ɾ༶޸İ༶Ϊҵ
	
v1.8
	* StudentManagerӿ
	* ѧ	
	
v1.9
	* ҵ޸İ༶
		
v2.0
	* ҵݹɾ༶	
	
v2.1
	* ҵҳѯѧ
	
v2.2
	* exam-config.properties
	* ݿϢõļ
	* ɸļĶȡ	
	* ÷StudentManagerĶ̬ʵ
		
v2.3
	* GradeManagerӿ		
	
v2.4
	* ҵ޸ѧ
	* ҵɾѧ
	* عStudentController
	
v2.5
	* ѧϢıļ		
	
v2.6
	* ӳɼ޸ĳɼɾɼ	
	* ̬ʵGradeManagerImpl
	* عGradeControllerMapݲ
	* StringTokenizerַֽ
	