菜品修改有问题
当列表里多个菜品信息，菜品修改后不能跳转到显示菜品信息界面，但是再去查询的时候发现修改成功；当列表里只有一条菜品信息时，就能跳转成功，感觉好迷呀
//菜品修改
public static void updateFood(Map<String,Food> map) {
//boolean flag=true;
Map<String,Food> map1 = null;
for(Map<String,Food> m : db) {
for(String key:m.keySet()){
for(String k:map.keySet()) {
if(map.get(k).getId().equals(m.get(key).getId())) {
map1 = m;
break;
}
}
}
db.remove(map1);
db.add(map);
}
}
package com.imooc.servlet;
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.ServletException;
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.FoodDaoImpl;
import com.imooc.utils.UploadUtils;
/**
* 菜品修改的Servlet
*/
public class FoodUpdateServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 文件上传的基本操作
try {
//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>();
//定义一个map集合用于保存菜品信息
Map<String,Food> foodMap = new HashMap<String,Food>();
// 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list集合，list中存放FileItem对象
List<FileItem> list = servletFileUpload.parseRequest(request);
// 4、遍历集合，获得FileItem，判断是普通表单项还是文件上传项
String url=null;
for(FileItem fileItem:list) {
if(fileItem.isFormField()) {
//普通表单项
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
//获得文件上传的名称
String fileName = fileItem.getName();
if(fileName!=null&& !"".equals(fileName)) {
//获得唯一的文件名
String uuidFileName = UploadUtils.getUUIDFileName(fileName);
//获得文件上传的数据
InputStream is = fileItem.getInputStream();
//获得路径
String path = this.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();
}
}
}
//获得ServletContext对象
//FoodDaoImpl foodDaoImpl = new FoodDaoImpl();
//List<Map<String,Food>> foodList = (List<Map<String, Food>>) this.getServletContext().getAttribute("list");
List<Map<String,Food>> foodList = FoodDaoImpl.getAllFood();
//校验菜品id是否存在
List<Map<String,Food>> idList = FoodDaoImpl.getFoodById(map.get("id"));
if(idList.size()!=0) {
//将数据封装到food类中
Food food = new Food();
food.setId(map.get("id"));
food.setFoodName(map.get("foodName"));
food.setTaste(map.get("taste"));
food.setPrice(map.get("price"));
food.setDescription(map.get("description"));
food.setPath(url);
//将菜品信息存入到list集合中
foodMap.put(food.getId(), food);
//foodDaoImpl.addFood(foodMap);
FoodDaoImpl.updateFood(foodMap);
//this.getServletContext().setAttribute("list", foodList);
//添加成功，跳转到显示菜品信息页面
System.out.println("修改成功！");
//request.getSession().setAttribute("foodList", foodList);
response.sendRedirect(request.getContextPath()+"/showFoodList.jsp");
}else {
request.setAttribute("msg", "该菜品id不存在！");
request.getRequestDispatcher("updateFood.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);
}
} <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort()
+ path;
%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>菜品修改（根据id修改）</title>
<style type="text/css">
</style>
</head>
<body>
<center>
<h1>根据菜品ID修改</h1>
<%
String msg="";
if(request.getAttribute("msg")!=null){
msg=(String)request.getAttribute("msg");
}
%>
<h3><font color="red"><%= msg %></font></h3>
<form action="<%= basePath %>/FoodUpdateServlet" method="post" enctype="multipart/form-data">
<table border="1px" width="400px" cellspacing="0px" cellpadding="0px">
<tr>
<td>修改ID</td>
<td><input type="text" name="id"></td>
</tr>
<tr>
<td>菜 名</td>
<td><input type="text" name="foodName"></td>
</tr>
<tr>
<td>口 味</td>
<td>
<input type="radio" name="taste" value="香辣">香辣
<input type="radio" name="taste" value="微辣">微辣
<input type="radio" name="taste" value="麻辣">麻辣
<input type="radio" name="taste" value="不辣">不辣
</td>
</tr>
<tr>
<td>菜品图片</td>
<td><input type="file" name="foodImage"></td>
</tr>
<tr>
<td>价 格</td>
<td><input type="text" name="price"></td>
</tr>
<tr>
<td>菜品描述</td>
<td>
<textarea name="description"></textarea>
</td>
</tr>
<tr style="text-align:center;width:20px">
<td colspan="2">
<input type="submit" value="修改">
<input type="reset" value="重置">
</td>
</tr>
</table>
</form>
</center>
</body>
</html><%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8" import="java.util.*,com.imooc.food.*"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort()
+ path;
%>
<!DOCTYPE html>
<html>
<head>
<base href="/immocPro2">
<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>
<%
//FoodDaoImpl foodDaoImpl = new FoodDaoImpl();
//List<Map<String, Food>> list = (List<Map<String, Food>>)session.getAttribute("foodList");
List<Map<String, Food>> list = FoodDaoImpl.getAllFood();
if (list.size() != 0) {
for (Map<String, Food> map : list) {
for (String key : map.keySet()) {
int idx = map.get(key).getPath().lastIndexOf("//");
String fileName = map.get(key).getPath().substring(idx + 1);
%>
<tbody>
<tr>
<td><%=map.get(key).getId()%></td>
<td><%=map.get(key).getFoodName()%></td>
<td><%=map.get(key).getTaste()%></td>
<td><img src="<%=basePath%>/upload/<%=fileName%>" /></td>
<td><%=map.get(key).getPrice()%></td>
<td><%=map.get(key).getDescription()%></td>
</tr>
<%
}
}
} else {
%>
<h3>
<font color="red">当前列表为空！</font>
</h3>
<%
}
%>
</tbody>
</table>
</center>
</body>
</html>0
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5回答
这是错误500的异常哦，500错误是代码出现了问题，错误原因是你在for循环中移除菜品信息了，所以会报错，建议你定义一个boolean类型的flag，默认值为false，当找到菜品信息时，将flag设置为true，然后在for循环外根据flag的值进行操作，祝学习愉快~
慕桂英8566455
2018-10-09 15:44:54
为什么我自己电脑上就不行啊，如图：
而且后台也没有打印出“修改成功！”，可是再去菜品查询的时候发现信息已经被修改了
chrismorgen
2018-10-09 15:18:07
你好同学，测试了你的代码，当列表中存在多个菜品信息时，在修改菜品信息时，是可以跳转到菜品信息查询页面的，下图是测试之后的结果，祝学习愉快~
慕桂英8566455
2018-10-09 14:21:50
package com.imooc.food;
public class Food {
private String id;
private String foodName;
private String taste;
private String path;
private String price;
private String description;
public Food() {
}
public Food(String id, String foodName, String taste, String path, String price, String description) {
super();
this.id = id;
this.foodName = foodName;
this.taste = taste;
this.path = path;
this.price = price;
this.description = description;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getFoodName() {
return foodName;
}
public void setFoodName(String foodName) {
this.foodName = foodName;
}
public String getTaste() {
return taste;
}
public void setTaste(String taste) {
this.taste = taste;
}
public String getPath() {
return path;
}
public void setPath(String path) {
this.path = path;
}
public String getPrice() {
return price;
}
public void setPrice(String price) {
this.price = price;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
@Override
public String toString() {
return "Food [id=" + id + ", foodName=" + foodName + ", taste=" + taste + ", path=" + path + ", price=" + price
+ ", description=" + description + "]";
}
}package com.imooc.food;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class FoodDaoImpl {
//存放菜品信息的List
private static final List<Map<String,Food>> db = new ArrayList<Map<String,Food>>();
//添加菜品
public static void addFood(Map<String,Food> map) {
db.add(map);
}
//查询所有菜品信息
public static List<Map<String,Food>> getAllFood(){
return db;
}
//根据菜品名称查询菜品信息
public static List<Map<String,Food>> getFoodByName(String name){
List<Map<String,Food>> list = new ArrayList<Map<String,Food>>();
boolean flag=false;
Map<String,Food> map=null;
for(Map<String,Food> l : db) {
for(String key:l.keySet()) {
if(l.get(key).getFoodName().equals(name)) {
map=l;
flag=true;
break;
}
}
}
if(flag)
list.add(map);
return list;
}
//根据菜品id查询菜品信息
public static List<Map<String,Food>> getFoodById(String id){
List<Map<String,Food>> list = new ArrayList<Map<String,Food>>();
Map<String,Food> map=null;
boolean flag = false;
for(Map<String,Food> l : db) {
for(String key:l.keySet()) {
if(l.get(key).getId().equals(id)) {
map=l;
flag=true;
break;
}
}
}
if(flag)
list.add(map);
return list;
}
//菜品修改
public static void updateFood(Map<String,Food> map) {
//boolean flag=true;
Map<String,Food> map1 = null;
for(Map<String,Food> m : db) {
for(String key:m.keySet()){
for(String k:map.keySet()) {
if(map.get(k).getId().equals(m.get(key).getId())) {
map1 = m;
break;
}
}
}
db.remove(map1);
db.add(map);
}
}
//根据菜品id进行删除
public static void deleteFoodById(String id) {
Map<String,Food> map = null;
for(Map<String,Food> l : db) {
for(String key:l.keySet()) {
if(l.get(key).getId().equals(id)) {
map = l;
break;
}
}
}
db.remove(map);
}
}
chrismorgen
2018-10-07 13:26:59
建议你把FoodUpdateServlet中的response.sendRedirect(request.getContextPath()+"/showFoodList.jsp");这段代码放到if else语句外试一试，如果我的建议解决了你的问题，请采纳，祝学习愉快~
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