biyelunwenbean.java

JSP开发的学生信息管理系统

package biyeLunwen;
import conn.DataBaseConnection;
import java.sql.Date;
import java.sql.*;
import java.util.*;
import java.io.*;
public class BiyeLunwenBean
{
	private Connection con=null;
	public BiyeLunwenBean()
	{
		this.con=DataBaseConnection.getConnection();
	}
	
	//是否存在学生
	public boolean existXuesheng(BiyeLunwen biyeLunwen) {
        boolean bool=false;
        try {
            String studentId = biyeLunwen.getStudentId();
            PreparedStatement pstmt = con.prepareStatement(
                    "select studentId from xuesheng where studentId='" +
                    studentId + "' and flag='"+1+"'");
            ResultSet rst = pstmt.executeQuery();
            if (rst.next()) {
                bool=true;
            }
            if(rst!=null){
        	rst.close();
        	}
        	if(pstmt!=null){
        		pstmt.close();
        	}
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        
        return bool;
    }
    
    //记录是否存在
    public boolean existBiyeLunwen(BiyeLunwen biyeLunwen) {
        try {
            String studentId = biyeLunwen.getStudentId();
            String designTime = biyeLunwen.getDesignTime();
            PreparedStatement pstmt = con.prepareStatement(
                    "select * from biyeLunwen where studentId='" +
                    studentId + "'");
            ResultSet rst = pstmt.executeQuery();
            if (rst.next()) {
                return true;
            }
        } catch (Exception ex) {
            return false;
        }
        return false;
    }
    
	//插入
	public String addBiyeLunwen(BiyeLunwen biyeLunwen)
	{
		PreparedStatement pstmt=null;
		String str="";
		try
		{
			if (!existXuesheng(biyeLunwen)) {
                return "notExist"; //不存在此学生
            }
            if (existBiyeLunwen(biyeLunwen)) {
                return "exist"; //此学生计算机等级记录已存在
            }
			pstmt=con.prepareStatement("insert into biyeLunwen values(?,?,?,?,?,?)");
			pstmt.setString(1,biyeLunwen.getStudentId());
			pstmt.setString(2,biyeLunwen.getTopical());
			pstmt.setString(3,biyeLunwen.getDesignTime());
			pstmt.setString(4,biyeLunwen.getScore());
			pstmt.setString(5,biyeLunwen.getFjName());
			pstmt.setString(6,biyeLunwen.getRemark());
			pstmt.execute();
			str="sucess";
		}catch(SQLException ex)
  	    	{
  	    		System.err.println(ex.getMessage());
  	    		str="failer";
  	    	}
  	    	finally
  	    	{
  	    		try{	
  	    		 if(pstmt!=null){
  	    		 	pstmt.close();
  	    		 }
  	    		 if(con!=null){
  	    		 	con.close();
  	    		 }
  	    		 
  	    		}catch(Exception e)
  	    		{
  	    			e.printStackTrace();
  	    		}
  	    	
  	    	}
  	    return str;	
	}
	//更新
	public String updateBiyeLunwen(BiyeLunwen biyeLunwen)
	{
		PreparedStatement pstmt=null;
		String str="";
		try
		{
			pstmt=con.prepareStatement("update biyeLunwen set topical=?,score=?,remark=? where studentId=?");
			pstmt.setString(1,biyeLunwen.getTopical());
			pstmt.setString(2,biyeLunwen.getScore());
			pstmt.setString(3,biyeLunwen.getRemark());
			pstmt.setString(4,biyeLunwen.getStudentId());
			pstmt.execute();
			str="sucess";
		}
		catch(SQLException ex)
  	    	{
  	    		System.err.println(ex.getMessage());
  	    		str="failer";
  	    	}
  	    	finally
  	    	{
  	    		try{	
  	    		 if(pstmt!=null){
  	    		 	pstmt.close();
  	    		 }
  	    		 if(con!=null){
  	    		 	con.close();
  	    		 }
  	    		}catch(Exception e)
  	    		{
  	    			e.printStackTrace();
  	    		}
  	    	
  	    	}
  	    return str;	
	}
	
	//删除
	public String deleteBiyeLunwen(String studentId)
	{
		PreparedStatement pstmt=null;
		String str="";
		try
		{
			pstmt=con.prepareStatement("delete from biyeLunwen where studentId=?"); 
			pstmt.setString(1,studentId);
			pstmt.execute();
			str="sucess";
		}
		catch(SQLException ex)
  	    	{
  	    		System.err.println(ex.getMessage());
  	    		str="failer";
  	    	}
  	    	finally
  	    	{
  	    		try{	
  	    		 if(pstmt!=null){
  	    		 	pstmt.close();
  	    		 }
  	    		 if(con!=null){
  	    		 	con.close();
  	    		 }
  	    		}catch(Exception e)
  	    		{
  	    			e.printStackTrace();
  	    		}
  	    	
  	    	}
  	    return str;	
	}
	//查询
	public ResultSet executeQuery(String sql)
  	{
  	     Statement stmt=null;
  	     ResultSet rst=null;
  	     try{
	  	      stmt=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
	  	      rst=stmt.executeQuery(sql);
  	    	}catch(SQLException ex)
  	    	{
  	    		System.err.println(ex.getMessage());
  	    	}
  	    	return rst;
  	 }
  	 //关闭
  	 public void close() 
        {
        	try{
  	    		 if(con!=null){
  	    		 	con.close();
  	    		 }
        	}
        	catch(SQLException e)
        	{
        	   e.printStackTrace();	
        	}
        	
        } 
        
    //所有班级
     public String getAllClass()
  {
  	Statement stmt = null;
    ResultSet rst = null;
    StringBuffer sBuf=new StringBuffer();
    try {
      stmt=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
	 rst=stmt.executeQuery("select distinct classId,className from banji");
      while(rst.next()) { 
        String classId= rst.getString("classId");
        String className= rst.getString("className");
        sBuf.append("<option value='"+classId+"'>"+className+"</option>\n");
        }
    }
    catch (SQLException ex) {
      return "";
    }
    return sBuf.toString();
  }
   
}