studentsvlt.java

这是书上的<java毕业设计指南与项目实践>的第6章:基于JSP+JavaBean+Servlet的课程管理系统,供大家参考

package com.course;
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class StudentSvlt extends HttpServlet{
	
public void doGet(HttpServletRequest req, HttpServletResponse res)
    throws ServletException, IOException {
    //获得学生ID	
    String stu_id =req.getParameter("id");
    int success = 0;
    // 获取请求中的参数
    String action = action = req.getParameter("action");
    student stu = null;
    String message="";
    //如果请求中包含新建学生参数
    if ("new".equalsIgnoreCase(action)) {
        // 调用新建学生方法
    	stu = doNew(req,res);
      // 并将新建学生存储在request上下文中，然后转向getStudent.jsp页面
      sendBean(req, res, stu, "/getStudent.jsp");
    }  
    //  如果请求中包含修改学生参数
    if ("update".equalsIgnoreCase(action)) {
    	try{
        // 调用修改学生信息方法	
     	stu = doUpdate(req,res, stu_id);
        // 并将修改后的学生信息存储在request上下文中，然后转向getStudent.jsp页面
     	sendBean(req,res,stu,"/getStudent.jsp");
     	   }
     	  catch(SQLException e){} 
    }
    //  如果请求中包含删除学生参数		   
    if ("delete".equalsIgnoreCase(action)) {
    	try{	
    	//调用删除学生方法
      	success = doDelete(stu_id);	
      	    }
      	    catch(SQLException e){}				
    	if (success != 1) {
    		doError(req, res, "StudentSvlt: Delete unsuccessful. Rows affected: " + success);
    	} else {
    		res.sendRedirect("http://localhost:8080/test/getStudent.jsp");
    	}
   
    }
    }
    
//新建学生方法定义 
 public student doNew(HttpServletRequest req,HttpServletResponse res )
                           throws ServletException,IOException{
      student stu= new student();                     	
      String stu_id=req.getParameter("id");
      String name=new String(req.getParameter("name").getBytes("ISO8859_1"));
      String password= req.getParameter("password");
      String dep=new String (req.getParameter("dep").getBytes("ISO8859_1"));
      String sex = new String(req.getParameter("sex").getBytes("ISO8859_1"));
      String jiguan = new String(req.getParameter("jiguan").getBytes("ISO8859_1"));
      if(isTrue(req,res,stu_id,name,password) && hasLogin(req,res,stu_id)){
      
      stu.setId(stu_id);
      stu.setName(name);
      stu.setPassword(password);
      stu.setDep(dep);
      stu.setSex(sex);
      stu.setJiguan(jiguan);
      stu.addStudent(); }  
      return stu;                	
                           	
                           	}
 //更新学生信息方法
 public student doUpdate(HttpServletRequest req,HttpServletResponse res , String id)
                           throws ServletException,IOException,SQLException {                      	
    student stu = new student();   
    String name=new String(req.getParameter("name").getBytes("ISO8859_1"));  
                 
    String password = req.getParameter("password");
    String dep = new String(req.getParameter("dep").getBytes("ISO8859_1"));
    String sex = new String(req.getParameter("sex").getBytes("ISO8859_1"));
    String jiguan = new String(req.getParameter("jiguan").getBytes("ISO8859_1"));
    if(isTrue(req,res,id,name,password)){
    stu.setId(id);
    stu.setName(name);
    stu.setPassword(password);
    stu.setDep(dep);
    stu.setSex(sex);
    stu.setJiguan(jiguan);
    stu.updateStudent();}
		return stu;
  }
  //删除学生方法
  public int doDelete(String id) throws SQLException {
  	int num=0;
    student stu=new student();
    num=stu.deleteStudent(id);
    return num;
  }
//保存学生信息的JavaBean到request上下文中
public void sendBean(HttpServletRequest req, HttpServletResponse res,
                       student stu, String target)
                       throws ServletException, IOException {
    req.setAttribute("stu", stu);
    RequestDispatcher rd = getServletContext().getRequestDispatcher(target);
    rd.forward(req, res);
  }
  
  //错误处理方法
  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);
  }
  //判断学生是否被注册过
  public boolean hasLogin(HttpServletRequest req, HttpServletResponse res,String id)
  throws ServletException, IOException{
  	boolean f=true;
  	String message="对不起，该学生号已经被注册过了!";
  	student stu= new student();
  	f= stu.hasLogin(id);
  	if(f==false){
  	doError(req,res,message);	
  		}
  		return f;
  	}
//判断学生注册是否成功
  public boolean isTrue(HttpServletRequest req, HttpServletResponse res,
                        String id,String name,String password)
                        throws ServletException, IOException {
   boolean f=true;                     	
   String message ="";
   if(id==null || id.equals(""))  {
   	f=false;
   	message="错误，学生号不能为空！";
   	doError(req,res,message);	}
   
   if(name==null || name.equals(""))  {
   	f=false;
   	message="学生姓名不能为空，请重新填写！";
   	doError(req,res,message);	}
  	
       
   if(password==null || password.equals(""))  {
   	f=false;
   	message="密码不能为空，请重新填写！";
   	doError(req,res,message);	}  

     return f;
     
  }
//响应post请求
  public void doPost(HttpServletRequest req, HttpServletResponse res)
    throws ServletException, IOException {

    doGet(req, res);

  }
	
	
}