markdb.java

使用JSP、Servlet以及JavaBean来实现学生成绩查询系统,简单好用

package mypack;
import java.sql.*;
import java.util.*;

public class MarkDB {
    //获取学生每门课的成绩	
	public static Student getMark(Connection con, String sid){
		PreparedStatement prepStmt = null;
	    ResultSet rs = null;
	    Course course = null;                 //存储课程有关信息
	    Student student = null;               //存储学生有关信息
	    Vector courses = new Vector();        //存储课程对象
	    String queryString =
	    	"select sname,gender,cname,type,kind,credit,period,mark" + 
	    	" from student,course,sc where student.sid = ? " + 
	    	"and student.sid = sc.sid and course.cid = sc.cid";
	    try{
	    	prepStmt = con.prepareStatement(queryString);
	    	prepStmt.setString(1, sid);
	    	rs = prepStmt.executeQuery();
	    	boolean temp = true;
	    	while(rs.next()){
	    		//创建学生对象
	    		if(temp){
	    		    student = new Student(sid,
	    				                  rs.getString("sname"),
	    				                  rs.getString("gender")
	    				                  );
	    		    temp = false;
	    		}
	    		//创建课程对象
	    		course = new Course(rs.getString("cname"),
	    				            rs.getString("type"),
	    				            rs.getString("kind"),
	    				            rs.getInt("credit"),
	    				            rs.getInt("period"),
	    				            rs.getInt("mark")
	    				           );
	    		courses.add(course);
	    	}
	    }catch(Exception e){
	    	e.printStackTrace();
	    }
	    //设置学生所修的课程
	    if(student != null)
	    	student.setCourses(courses);
	    
	    return student;
	}
}