菜品添加功能实现了,修改删除和查询有问题

1.老师我接收数据的方法写在一个java类里,这样有什么问题吗?
2.菜品修改功能点击修改之后,页面跳转到一个白页,是是因为共用这个接收数据的方法有问题吗?还是FoodDaolpml这个类里面的bd集合不是同一个,所以修改的时候里面没有所以出现白页?或者是其他什么原因?
3.点击删除和根据菜品名称查询,页面重定向都不成功,跳转到一个白页
package com.imooc.food.utiles;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import com.imooc.food.Food;
public class UploadFileData {
 /**
  * 文件的数据接收类
  * @throws IOException 
  */
 public static Food UploadFile(HttpServletRequest request) throws IOException{
  String url=null;
  //定义一个Map集合用于保存接收到的数据
  Map<String ,String>map =new HashMap<String ,String>();
  //创建一个磁盘文件项工厂对象
  DiskFileItemFactory diskFileItemFactory =new DiskFileItemFactory();
  //创建一个核心解析类
  ServletFileUpload servletFileUpload =new ServletFileUpload(diskFileItemFactory);
  //解析request请求,返回的是List集合,集合中存放的是FileItem对象
  List<FileItem> list;
  try {
   list = servletFileUpload.parseRequest(request);
   //遍历集合,获得每个FileItem,判断是表单项还是文件上传项
   for (FileItem fileItem : list) {
    if (fileItem.isFormField()) {
     String name=fileItem.getFieldName();
     String value =fileItem.getString("UTF-8");
     System.out.println(name +"    " +value);
     map.put(name,value);
    }else{
     //文件上传项
     //文件上传功能
     //获得上传文件的名称
     String FileName =fileItem.getName();
     //通过工具类获得唯一文件名
     String uuidFileName = UploadUtils.getUUIDFileName(FileName);
     //获得文件上传数据
     InputStream is = fileItem.getInputStream();
     //获得文件上传的路径
     String path =request.getServletContext().getRealPath("/upload");
     //将输入流对接到输出流
     url =path + "\\"  + uuidFileName;
     
     OutputStream os = new FileOutputStream(url);
     
     int len = 0;
     byte[] b = new byte[1024];
     while((len = is.read(b))!= -1){
      os.write(b, 0, len);
     }
     is.close();
     os.close();
    }
   }
  } catch (FileUploadException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  System.out.println(map);
  Food food=new Food();
  food.setId(map.get("id"));
  food.setName(map.get("foodName"));
  food.setPrice(map.get("price"));
  food.setDescribe(map.get("describe"));
  food.setTaste(map.get("taste"));
  food.setFoodAdress(url);
  return food;
  }
}
 

package com.imooc.food.servlet;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import com.imooc.food.Food;
import com.imooc.food.FoodDaolmpl;
import com.imooc.food.utiles.UploadFileData;
import com.imooc.food.utiles.UploadUtils;
/**
 * 菜品添加的Servlet
 */
@WebServlet("/FoodAddServlet")
public class FoodAddServlet extends HttpServlet {
 protected void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  // 数据的接收
  Food food = UploadFileData.UploadFile(request);
  FoodDaolmpl.addFood(food);
  // 添加成功,跳转到查询页面
  response.sendRedirect(request.getContextPath() + "/showFoodList.jsp");
 }
 /**
  * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
  *      response)
  */
 protected void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  // TODO Auto-generated method stub
  doGet(request, response);
 }
}


package com.imooc.food.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.imooc.food.Food;
import com.imooc.food.FoodDaolmpl;
import com.imooc.food.utiles.UploadFileData;
/**
 * Servlet implementation class FoodUpdateServlet
 */
@WebServlet("/FoodUpdateServlet")
public class FoodUpdateServlet extends HttpServlet {
 
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  Food food=UploadFileData.UploadFile(request); 
  FoodDaolmpl.updateFood(food);
  
  //修改成功,跳转到查询页面
  response.sendRedirect(request.getContextPath()+"/showFoodList.jsp");
 }
 /**
  * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
  */
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub
  doGet(request, response);
 }
}

package com.imooc.food.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.imooc.food.Food;
import com.imooc.food.FoodDaolmpl;

/**
 * Servlet implementation class SelectServlet
 */
@WebServlet("/SelectServlet")
public class SelectServlet extends HttpServlet {
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  String name =request.getParameter("foodName");
  Food food =FoodDaolmpl.getFoodByName(name);
  request.setAttribute("food", food);
  
  //查询成功,返回到查询界面
  response.sendRedirect(request.getContextPath()+"/showFoodList.jsp");
 }

 /**
  * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
  */
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub
  doGet(request, response);
 }

}

package com.imooc.food.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.imooc.food.Food;
import com.imooc.food.FoodDaolmpl;

/**
 * Servlet implementation class FoodDeleteServlet
 */
@WebServlet("/FoodDeleteServlet")
public class FoodDeleteServlet extends HttpServlet {
 
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  String id =request.getParameter("id");
  for (Food food : FoodDaolmpl.getAllFood()) {
   if(food.getName().equals("id")){
    FoodDaolmpl.deleteFoodById(id);
    request.getRequestDispatcher("/showFoodList.jsp").forward(request, response);
   }else{
    request.getRequestDispatcher("/showFoodList.jsp").forward(request, response);
   }
  }
 }

 /**
  * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
  */
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub
  doGet(request, response);
 }

}