删除图书分类管理
package com.imooc.web.servlet;
import java.io.IOException;
import javax.servlet.ServletContext;
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.alibaba.fastjson.JSON;
import com.imooc.service.impl.CategoryServiceImpl;
/**
* Servlet implementation class addCategory
*/
@WebServlet("/addCategory")
public class addCategory extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public addCategory() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
//response.getWriter().append("Served at: ").append(request.getContextPath());
request.setCharacterEncoding("UTF-8");
String classId=request.getParameter("categoryId");
String className=request.getParameter("categoryName");
CategoryServiceImpl csi=new CategoryServiceImpl();
csi.addCategory(classId, className);
request.getSession().setAttribute("category", csi.getCategorydb());
System.out.println("classId"+classId+" className"+className);
request.getRequestDispatcher("/categoryList.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);
}
}
package com.imooc.service.impl;
import java.util.ArrayList;
import java.util.List;
import com.imooc.domain.Category;
import com.imooc.service.CategoryService;
public class CategoryServiceImpl implements CategoryService {
private static final List<Category> categoryDb=new ArrayList<Category>();
public static List<Category> getCategorydb() {
return categoryDb;
}
@Override
public void addCategory(String categoryId, String catgoryName) {
// TODO Auto-generated method stub
Category cg=new Category();
cg.setClassId(categoryId);
cg.setClassName(catgoryName);
categoryDb.add(cg);
}
@Override
public void deleteCategory(String categoryId) {
// TODO Auto-generated method stub
for(Category c:categoryDb) {System.out.println("categoryId:"+categoryId+" c.categoryId:"+c.getClassId());
if(c.getClassId().equals(categoryId)) {
categoryDb.remove(c);
return;
}
}
}
}
package com.imooc.domain;
public class Category {
private String classId;
private String className;
public String getClassId() {
return classId;
}
public void setClassId(String classId) {
this.classId = classId;
}
public String getClassName() {
return className;
}
public void setClassName(String className) {
this.className = className;
}
@Override
public String toString() {
return "Category [classId=" + classId + ", className=" + className + "]";
}
/*
* classId 图书分类ID
* className 分类名称
*/
public Category(String classId, String className) {
super();
this.classId = classId;
this.className = className;
}
public Category() {
super();
// TODO Auto-generated constructor stub
}
}
package com.imooc.web.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.service.impl.CategoryServiceImpl;
/**
* Servlet implementation class deleteCategory
*/
@WebServlet("/deleteCategory")
public class deleteCategory extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public deleteCategory() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
//response.getWriter().append("Served at: ").append(request.getContextPath());
String classId=request.getParameter("categoryId");System.out.println("*****************");
System.out.println("categoryId:"+classId);
CategoryServiceImpl csi=new CategoryServiceImpl();
csi.deleteCategory(classId);
request.getSession().setAttribute("category", csi.getCategorydb());
request.getRequestDispatcher("/categoryList.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);
}
}
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix = "c" %>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>图书后台管理</title>
<link rel="stylesheet" href="css/index.css">
<link rel="stylesheet" href="css/bootstrap.min.css">
</head>
<script type="text/javascript" src="js/jquery-3.4.1.js"></script>
<script type="text/javascript">
$(function(){
$.ajax({
})
})
</script>
<body>
<header>
<div class="container">
<nav>
<a href="bookList.html" >图书信息管理</a>
</nav>
<nav>
<a href="categoryList.html" >分类管理</a>
</nav>
</div>
</header>
<section class="banner">
<div class="container">
<div>
<h1>图书管理系统</h1>
<p>图书分类管理</p>
</div>
</div>
</section>
<section class="main">
<div class="container">
<table class="table table-striped">
<thead>
<tr>
<th>序号</th>
<th>分类编号</th>
<th>分类名称</th>
<th>操作</th>
</tr>
</thead>
<tbody>
<c:forEach items="${category}" var="ca" varStatus="idx">
<tr>
<td>${idx.index}</td>
<td>${ca.classId}</td>
<td>${ca.className}</td>
<td><a href="/zuoyebook/deleteCategory?categoryId=${ca.classId}">删除</a></td>
<!--在循环显示数据时，此处的ca0001可以用EL表达式进行替换-->
</tr>
</c:forEach>
</tbody>
</table>
</div>
</section>
<section class="page">
<div class="container">
<div id="fatie">
<a href="addCategory.html"><button>新建</button></a>
</div>
</div>
</section>
<footer>
copy@慕课网
</footer>
</body>
</html>
点击删除后出现500的情况或者序号和操作还存在的情况，老师，这是哪里有问题？
正在回答 回答被采纳积分+1
同学你好，1. SendRedirect 重定向，浏览器地址栏变为目标地址。而forword转发，浏览器地址栏不变，当刷新页面时会添加或删除无效的数据。所以需要使用 重定向。
2. 区别： request.getRequestDispatcher()是请求转发，前后页面共享一个request 。
response.sendRedirect()是重新定向，前后页面不是一个request。
RequestDispatcher.forward()是在服务器端运行。
HttpServletResponse.sendRedirect()是通过向客户浏览器发送命令来完成。
3. SendRedirect 重定向，url是截止到项目名前,例如:http://127.0.0.1:8080/ 访问页面时候需要加上项目名，如项目为ssm ：response.sendRedirect("/ssm/loginPage")
而forword转发，url是截止到项目名后，例如：http://127.0.0.1:8080/ssm/ 访问页面直接写访问地址： 如项目为ssm ：request.getRequestDispacther("/login.jsp").forword(request,response)
如果我的回答解决了你的疑惑，请采纳！祝学习愉快！
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