根据菜名查询不出

1.package com.imooc.domain;

import java.util.ArrayList;

import java.util.List;

public class FoodDaoImpl {

private static final List<Food> db = new ArrayList<Food>();

/**

* 添加菜品

* @param food

*/

public void addFood(Food food) {

db.add(food);

}

/**

* 查询所有菜品信息

* @return

*/

public List<Food> getAllFood() {

return db;

} 

/**

* 根据菜品名称查询菜品信息

* @param foodName

* @return

*/

public Food getFoodByName(String foodName) {

return null;

}

/**

* 根据菜品id查询菜品信息

* @param id

* @return

*/

public Food getFoodById(String id) {

return null;

}

/**

* 菜品修改

* @param newFood

*/

public void updateFood(Food newFood) {

}

/**

* 根据菜品id进行删除

* @param id

*/

public void deleteFoodById(String id) {

}

}

2.package com.imooc.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.domain.Food;

import com.imooc.domain.FoodDaoImpl;

import com.imooc.utils.UploadUtils;

/**

 * Servlet implementation class FoodAddServlet

 */

@WebServlet("/FoodAddServlet")

public class FoodAddServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

try {

//定义一个Map集合用于保存接受到的数据

Map<String,String> map = new HashMap<String,String>();

//1.创建一个磁盘文件项工厂对象

DiskFileItemFactory diskFileItemFactory = new DiskFileItemFactory();

//2.创建一个核心解析类

ServletFileUpload servletFileUpload = new ServletFileUpload(diskFileItemFactory);

//3.解析request请求，返回的是List集合，List集合中存放的是FileItem对象

List<FileItem> list = servletFileUpload.parseRequest(request);

//定义一个List集合，用于保存复选框口味的数据

List<String> tasteList = new ArrayList<String>();

//4.遍历集合，获得每个FileItem，判断是表单项还是文件上传项

String url = null;

for (FileItem fileItem : list) {

//判断是表单项还是文件上传项

if(fileItem.isFormField()) {

//普通表单项

//接受表单项参数的值

String name = fileItem.getFieldName();//获得表单项的name属性的值

String value = fileItem.getString("UTF-8");//获得表单项的值

//接受复选框的数据

if("taste".equals(name)) {

String tasteValue = fileItem.getString("UTF-8");

//接收到一个值，将这个值存入到tasteList集合中

tasteList.add(tasteValue);

tasteValue = tasteList.toString().substring(1, tasteList.toString().length()-1);

//将口味的数据存入到Map集合中

map.put(name, tasteValue);

}else {

//将普通数据存入到Map集合中

map.put(name, value);

}

}else {

//文件上传项

//文件上传功能

//获得文件上传的名称

String fileName = fileItem.getName();

if(fileName!=null && !"".equals(fileName)) {

//通过工具类获得唯一文件名

String uuidFileName = UploadUtils.getUUIDFileName(fileName);

//获得文件上传的数据

InputStream is = fileItem.getInputStream();

//获得文件上传的路径

String path = this.getServletContext().getRealPath("/upload");

url = path + "\\" + uuidFileName;

//将输入流对接到输出流

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();

}

}

}

//获得FoodDaoImpl对象

FoodDaoImpl foodDaoImpl = new FoodDaoImpl();

List<Food> foodList = foodDaoImpl.getAllFood();

for (Food f : foodList) {

if(f.getId()==Integer.parseInt(map.get("id"))) {

request.setAttribute("msg", "菜品id已经存在！");

request.getRequestDispatcher("/addFood.jsp").forward(request, response);

return;

}

}

//封装数据到Food中

Food food = new Food();

food.setId(Integer.parseInt(map.get("id")));

food.setFoodName(map.get("foodName"));

food.setTaste(map.get("taste"));

food.setPrice(Double.parseDouble(map.get("price")));

food.setFoodImage(url);

food.setDescription(map.get("description"));

//将菜品信息存入到List集合中

foodDaoImpl.addFood(food);

for (Food fd : foodList) {

System.out.println(fd);

}

this.getServletContext().setAttribute("list", foodList);

//response.sendRedirect(request.getContextPath() + "/showFoodList.jsp");

request.getRequestDispatcher("/showFoodList.jsp").forward(request, response);

} catch (FileUploadException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

doGet(request, response);

}

}

3.package com.imooc.servlet;

import java.io.IOException;

import java.util.List;

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.domain.Food;

/**

 * Servlet implementation class SelectServlet

 */

@WebServlet("/SelectServlet")

public class SelectServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

request.setCharacterEncoding("UTF-8");

String foodName = request.getParameter("foodName");

if(foodName.equals("")||foodName==null) {

this.getServletContext().getAttribute("list");

request.getRequestDispatcher("/showFoodList.jsp").forward(request, response);

}else {

List<Food> fd = (List<Food>) this.getServletContext().getAttribute("list");

for (Food food : fd) {

System.out.println(food.getFoodName());

System.out.println(foodName);

if(foodName.equals(food.getFoodName())) {

this.getServletContext().setAttribute("list", food);

request.getRequestDispatcher("/showFoodList.jsp").forward(request, response);

return;

}

}

}

System.out.println(foodName);

}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

doGet(request, response);

}

}

4.

<%@page import="java.util.*"%>

<%@page import="com.imooc.domain.Food"%>

<%@page import="org.apache.jasper.tagplugins.jstl.core.ForEach"%>

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>

<!DOCTYPE html>

<html>

<head>

<base href="<%=basePath%>">

<meta http-equiv="Content-Type" content="text/html; charset=utf-8">

<title>菜品信息展示</title>

<style type="text/css">

</style>

</head>

<body>

<center>

<h1>菜品查询</h1>

<table border="1px" cellspacing="0px" cellpadding="0px" width="800px">

<thead>

<tr>

<th>菜品ID</th>

<th>菜名</th>

<th>口味</th>

<th>菜品图片</th>

<th>价格</th>

<th>菜品描述</th>

</tr>

</thead>

<tbody>

<%

List<Food> foodList = (List<Food>)application.getAttribute("list");

System.out.println(foodList);

for(Food fd : foodList){

Object id = fd.getId();

Object foodName = fd.getFoodName();

Object taste = fd.getTaste();

int idx = fd.getFoodImage().lastIndexOf("\\");

String filePath = fd.getFoodImage().substring(idx+1);

Object price = fd.getPrice();

Object description = fd.getDescription();

%>

<tr>

<td><%=id %></td>

<td><%=foodName %></td>

<td><%=taste %></td>

<td><img src="/menu_system/upload/<%=filePath%>"/></td>

<td><%=price %></td>

<td><%=description %></td>

</tr>

<%

}

%>

</tbody>

</table>

</center>

</body>

</html>

老师，上面分别是1.FoodDaoImpl  2.FoodAddServlet  3.SelectServlet  4.showFoodList.jsp，现在根据菜名查询如果我不输入任何值的话能查出全部，但如果我输入某一个词就显示500错误了