80346d8ee6ac001d12e9c6aae1085a9a

jsp的课程实践

package course.dao;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;

import student.dao.DataBase;
import course.beans.Course;
public class CourseDAO {
    private DataBase db;
    public CourseDAO()
    {
    	super();
    	db=new DataBase();
    }
    public Course getCourseInfo(String id)
    {
    	Course course=null;
    	try
    	{
    		String sql="select * from course where courseId='"+id+"'";
    		ResultSet rst =db.executeQuery(sql);
    		while(rst.next())
    		{
    			String courseId=rst.getString("courseId");
    			String courseName=rst.getString("courseName");
    			String teacher=rst.getString("teacher");
    			String courseDes=rst.getString("courseDes");
    			int credit=rst.getInt("credit");
    			course=new Course(courseId,courseName,teacher,courseDes,credit);
    		}
    	}
    	catch(SQLException ex)
    	{
    		ex.printStackTrace();
    	}
    	return course;
    }
    public ArrayList<Course> getAllCourse()
    {
    	ArrayList<Course> list=new ArrayList<Course>();
    	try
    	{
    		String sql="select * from course";
    		ResultSet rst=db.executeQuery(sql);
    		while(rst.next())
    		{
    			Course course=null;
    			String courseId=rst.getString("courseId");
    			String courseName=rst.getString("courseName");
    			String teacher=rst.getString("teacher");
    			String courseDes=rst.getString("courseDes");
    			int credit=rst.getInt("credit");
    			course=new Course(courseId,courseName,teacher,courseDes,credit);
    			list.add(course);
    		}
    	}
    	catch(SQLException ex)
    	{
    		ex.printStackTrace();
    	}
    	return list;
    }
   
   /* public ArrayList<Course>findCourse(String argCourseId,String argCourseName,String argTeacher,String argCourseDes,String argCredit)
    {
    	ArrayList<Course>courses=new ArrayList<Course>();
    	String sql="select * from course where courseId='"+ argCourseId +"' or courseName='"+argCourseName+"' or teacher='"+
    	argTeacher+"' or courseDes='"+argCourseDes+"' or credit='"+argCredit+"'";
    	try
    	{
    		ResultSet rst=db.executeQuery(sql);
			while(rst.next())
			{
				Course course=null;
    			String courseId=rst.getString("courseId");
    			String courseName=rst.getString("courseName");
    			String teacher=rst.getString("teacher");
    			String courseDes=rst.getString("courseDes");
    			int credit=rst.getInt("credit");
    			course=new Course(courseId,courseName,teacher,courseDes,credit);
    			courses.add(course);
			}
    	}
    	catch(SQLException ex)
    	{
    		ex.printStackTrace();
    	}
    	return courses;
    }*/
    public ArrayList<Course>findCourse(String argCourseId,String argCourseName,String argTeacher,String argCourseDes,String argCredit)
	{
    	ArrayList<Course>courses=new ArrayList<Course>();
		//利用编码技巧实现实现SQL语句查询
		String conditionSql="";
		String whereSql="where";
		if((argCourseId==null||argCourseId.equals(""))||(argCourseName==null||argCourseName.equals(""))&&(argTeacher==null||argTeacher.equals(""))&&
				(argCourseDes==null||argCourseDes.equals(""))&&(argCredit==null||argCredit.equals("")))
		{
			whereSql="";
		}
		else
		{
			if(argCourseId!=null&&!argCourseId.equals(""))
			{
			    conditionSql+="courseId like '%"+argCourseName+"%' or ";
			}
			if(argCourseName!=null&&!argCourseName.equals(""))
			{
				conditionSql+="courseName like '%"+argCourseName+"%' or ";
			}
			if(argTeacher!=null && !argTeacher.equals(""))
			{
				conditionSql+="teacher like '%"+argTeacher+"%' or ";
			}
			if(argCourseDes!=null &&!argCourseDes.equals(""))
			{
				conditionSql+="courseDes like '%"+argCourseDes+"%' or ";
			}
			if(argCredit!=null && !argCredit.equals(""))
			{
				conditionSql+="credit like '%"+argCredit+"%' or ";
			}
			if(!conditionSql.equals(""))
			{
				conditionSql=conditionSql.substring(0, conditionSql.length()-3);
			}
		}
		
		String sql="select * from course "+ whereSql+conditionSql;
		try
    	{
    		ResultSet rst=db.executeQuery(sql);
			while(rst.next())
			{
				Course course=null;
    			String courseId=rst.getString("courseId");
    			String courseName=rst.getString("courseName");
    			String teacher=rst.getString("teacher");
    			String courseDes=rst.getString("courseDes");
    			int credit=rst.getInt("credit");
    			course=new Course(courseId,courseName,teacher,courseDes,credit);
    			courses.add(course);
			}
    	}
        catch(SQLException ex){
        	ex.printStackTrace();
        }
        
		return courses;
	}
}