myclasssvlt.java

采用基于B/S结构进行开发学生管理信息系统,本系统采用Servlet+Jsp+JavaBean+MySQL 的设计方式

import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
import myBean.MyClass;

public class MyClassSvlt extends HttpServlet{
	
public void doGet(HttpServletRequest req, HttpServletResponse res)
    throws ServletException, IOException {
    String class_id =req.getParameter("class_id");
    int success = 0;
    String action = req.getParameter("action");
    MyClass cla = null;
    String message="";
   	
   if ("new".equalsIgnoreCase(action)) {
   	  //class_id=req.getParameter("class_id");
   	  
  	  if(isTrue(req,res,class_id) && hasLogin(req,res,class_id)){
         cla = doNew(req,res,class_id);      
         sendBean(req, res, cla, "/getClass.jsp");
        }
    }  
    
    if ("update".equalsIgnoreCase(action)) {    	
      //class_id = req.getParameter("class_id"); 
      if(isTrue(req,res,class_id)){
    	   try{		
     	       cla = doUpdate(req,res,class_id);
     	       sendBean(req,res,cla,"/getClass.jsp");
            }
     	   catch(SQLException e){} 
     	  }
    }
			   
    if ("delete".equalsIgnoreCase(action)) {
    	try{			
      	success = doDelete(req,res,class_id);	
      	    }
      	    catch(SQLException e){}				
    	if (success == 0) {
    		doError(req, res, "这个班级中还有学生，不能删除它！ " );
    	} else {
    		res.sendRedirect("http://localhost:8080/0903/getClass.jsp");
    	}   
    }
    }
    

 public MyClass doNew(HttpServletRequest req,HttpServletResponse res,String class_id)
                           throws ServletException,IOException{
      MyClass cla= new MyClass(); 
      String dep=req.getParameter("dep_id"); 
      int year = Integer.parseInt(req.getParameter("entry"));                  	
      
      cla.setId(class_id);
      cla.setEntry(year);
      cla.setDep_id(dep);
      
      int num=cla.addClass(); 
      return cla;                	           	
 	}

 public MyClass doUpdate(HttpServletRequest req,HttpServletResponse res ,String id)
                           throws ServletException,IOException,SQLException {                            	                     	
    MyClass cla = new MyClass();    
    String monitor = req.getParameter("monitor");             
    
    cla.setId(id);
    cla.setMonitor(monitor);
    cla.updateClass();
  
		return cla;
  }

  public int doDelete(HttpServletRequest req,HttpServletResponse res,String id) throws ServletException,SQLException,IOException {
  	int num=0;
    MyClass cla=new MyClass();
    num=cla.deleteClass(id);
    return num;
  }
	
public void sendBean(HttpServletRequest req, HttpServletResponse res,
                       MyClass cla, String target)
                       throws ServletException, IOException {
    req.setAttribute("cla", cla);
    RequestDispatcher rd = getServletContext().getRequestDispatcher(target);
    rd.forward(req, res);
  }
  
  
  public void doError(HttpServletRequest req,
                      HttpServletResponse res,
                      String str)
                      throws ServletException, IOException {


    req.setAttribute("problem", str);
    RequestDispatcher rd = getServletContext().getRequestDispatcher("/errorpage.jsp");
    rd.forward(req, res);
  }
  
  public boolean hasLogin(HttpServletRequest req, HttpServletResponse res,String id)
  throws ServletException, IOException{
  	boolean f=true;
  	String message="对不起，该班级号已经被注册过了!";
  	MyClass cla= new MyClass();
  	f= cla.hasLogin(id);
  	if(f==false){
  	doError(req,res,message);	
  		}
  		return f;
  	}
  
  public boolean isTrue(HttpServletRequest req, HttpServletResponse res,
                        String id)
                        throws ServletException, IOException {
   boolean f=true;                     	
   String message ="";
   if(id==null || id.equals(""))  {
   	 f=false;
   	 message="错误，班级号不能为空！";
   	 doError(req,res,message);	
   }
   
     return f;     
  }
  
  public void doPost(HttpServletRequest req, HttpServletResponse res)
    throws ServletException, IOException {

    doGet(req, res);

  }
	
	
}