这是什么原因啊老师帮忙看一下，谢谢

package com.imooc.web.service.impl;

import java.util.ArrayList;

import java.util.List;

import com.imooc.domain.Book;

import com.imooc.domain.Category;

import com.imooc.web.service.BookService;

public class BookServiceImp implements BookService {

private static final List<Book> books = new ArrayList<Book>();

public static List<Book> getBooks(){

return books;

}

// 添加图书

@Override

public void addBook(Book book) {

// 在books集合列表中查找，＝＝－1 ，如果没有

if(books.indexOf(book)==-1) {

books.add(book);

}else {

System.out.println("该书籍已经存在");

return;

}

// 修改图书

@Override

public void updateBook(Book book) {

for(Book bk:books) {

if(bk.getBookId().equals(book.getBookId())) {

bk.setBookName(book.getBookName());

bk.setBookPrice(book.getBookPrice());

bk.setCategoryName(book.getCategoryName());

bk.setRemarks(book.getRemarks());

bk.setBookPic(book.getBookPic());

}

//删除图书

@Override

public void deleteBook(String bookId) {

for(Book book:books) {

if(book.getBookId().equals(bookId)) {

books.remove(book);

break;

}

// 根据图示id查询图书

@Override

public Book getBooksById(String bookID) {

// TODO Auto-generated method stub

return null;

}

//根据分类查询书籍信息

@Override

public List<Book> getBooksByCatgoryName(String catgoryName) {

// TODO Auto-generated method stub

return null;

}

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.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.Book;

import com.imooc.web.service.impl.BookServiceImp;

@WebServlet("/AddBookServlet")

public class AddBookServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

public AddBookServlet() {

super();

}

protected void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

// 创建map用于保存用户数据

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

// 创建磁盘工厂

DiskFileItemFactory diskfileitemfactory = new DiskFileItemFactory();

// 解析核心类

ServletFileUpload fileUpload = new ServletFileUpload(diskfileitemfactory);

// 请求解析对象，将请求分成几个部分（FileItem）

// 4. 遍历集合获得每个部分的对象

try {

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

for (FileItem fileitem : list) {

// 判断是普通项还是文件上传项

if (fileitem.isFormField()) {

// 普通项

// 获得普通项名称

String name = fileitem.getFieldName();

// 获得普通项的值

String value = fileitem.getString("UTF-8");

// 保存数据

map.put(name, value);

} else {

String fileName = fileitem.getName();

// 获得文件输入流

InputStream ips = fileitem.getInputStream();

// 将文件写入到服务器

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

// 创建文件输出流,与输入流进行对接

String url = path + "/" + fileName;

map.put("path", request.getContextPath() + "/upload/" + fileName);

OutputStream ops = new FileOutputStream(url);

int len = 0;

byte[] b = new byte[1024];

while ((len = ips.read(b)) != -1) {

ops.write(b, 0, len);

}

ips.close();

ops.close();

}

} catch (FileUploadException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

// 封装数据

Book book = new Book();

book.setBookId(map.get("bookId"));

book.setBookName(map.get("bookName"));

book.setCategoryName(map.get("categoryName"));

book.setBookPrice(map.get("bookPrice"));

book.setBookPic(map.get("path"));

book.setRemarks(map.get("remarks"));

// 处理数据

BookServiceImp booksrevice = new BookServiceImp();

booksrevice.addBook(book);

request.getSession().setAttribute("bookList", booksrevice.getBooks());

System.out.println(booksrevice.getBooks());

// 显示结果

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

}

protected void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

// TODO Auto-generated method stub

doGet(request, response);

}

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.Book;

import com.imooc.web.service.impl.BookServiceImp;

@WebServlet("/UpdateBook")

public class UpdateBook extends HttpServlet {

private static final long serialVersionUID = 1L;

public UpdateBook() {

super();

// TODO Auto-generated constructor stub

}

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

//接收用户信息

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

Book book = new Book();

book.setBookId(bookId);

BookServiceImp bk= new BookServiceImp();

bk.updateBook(book);

//处理用户信息

request.getServletContext().setAttribute("bookList",bk.getBooks());

request.getRequestDispatcher("/updateBook.jsp").forward(request, 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>

<head>

<title>新建图书信息</title>

function checkForm() {

var id = $("#bookId").val();

var name = $("#bookName").val();

var categoryId = $("#categoryId").val();

var price = $("#bookPrice").val();

var remarks = $("#remarks").val();

var regex = /(^[1-9]\d*(\.\d{1,2})?$)|(^0(\.\d{1,2})?$)/;

if (id == "" || id == null) {

alert("编号不能为空");

return false;

} else if (name == "" || name == null) {

alert("书名不能为空");

return false;

} else if (categoryId == "" || categoryId == null) {

alert("请先添加分类");

return false;

} else if (price == "" || price == null) {

alert("价格不能为空");

return false;

} else if (regex.test(price) == false) {

alert("价格格式不正确!");

return false;

} else if (remarks == "" || remarks == null) {

alert("备注不能为空");

return false;

}

alert("图书添加成功");

return true;

}

</script>

</head>

<body>

<a class="navbar-brand" href="/dept/list.do"> 图书信息管理 </a>

</div>

</nav>

<h1>Hello, XXX!</h1>

<p>请小心地新增图书信息，要是建了一个错误的就不好了。。。</p>

</div>

<h3>

</h3>

</div>

<form class="form-horizontal"

action="${pageContext.request.contextPath }/AddBookServlet"

method="post" onsubmit="return checkForm()"

enctype="multipart/form-data">

</div>

</div>

<select id="categoryId" name="categoryName"

class="col-sm-2 form-control"

style="width: auto; margin-left: 15px">

<c:forEach items="${sessionScope.cateList }" var="c"

varStatus="idx">

<option value="${c.categoryName }" selected="selected">{c.categoryName

}</option>

</c:forEach>

</select>

</div>

</div>

<label for="name" class="col-sm-2 control-label">图书封面：</label> <input

type="file" id="bookPic" name="bookPic" style="padding-left: 15px">

</div>

</div>

</div>

</form>

</div>

<footer class="text-center"> copy@imooc </footer>

</body>

</html>

<%@ 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>

<head>

<title>修改图书信息</title>

</head>

<body>

图书信息管理

</a>

</div>

</nav>

<h1>Hello, XXX!</h1>

<p>请小心的修改图书信息。。。</p>

</div>

</div>

</div>

</div>

<c:forEach items="${sessionScope.cateList }" var="c"

varStatus="idx">

<option value="${c.categoryName }" selected="selected">{c.categoryName

}</option>

</c:forEach>

</select>

</div>

</div>

</div>

</div>

</div>

</form>

</div>

copy@imooc

</footer>

</body>

</html>

<%@ 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>

<head>

<title>图书后台管理</title>

</head>

<body>

<nav>

<a href="bookList.jsp">图书信息管理</a>

</nav>

<nav>

</nav>

</div>

</header>

<div>

<h1>图书管理系统</h1>

<p>图书信息管理</p>

</div>

</section>

</div>

<input name="searchContent" class="form-control"

id="searchContent" placeholder="输入要查询的分类" style="width: 250px">

</div>

</form>

</div>

<thead>

<tr>

</tr>

</thead>

<tbody>

<c:forEach items="${sessionScope.bookList}" var="book"

varStatus="idx">

<td>${idx.index+1}</td>

<td>${book.bookId}</td>

<td>${book.bookName}</td>

<td>${book.categoryName}</td>

<td>￥${book.bookPrice}</td>

<td><a href="${pageContext.request.contextPath }/UpdateBook?bookId=${book.bookId}">修改</a> <a

href="/deleteBook?bookId=book0001">删除</a></td>

</tr>

</c:forEach>

</tbody>

</table>

</div>

</section>

</div>

</section>

</body>

</html>

两个问题

第一个：为什下拉框无法显示中文啊，只显示

${c.categoryName }

第二个：修改图书回出现新的一行，无法覆盖，如图

J_DP 2020-07-06

源自：项目：登录注册功能 6-2 项目作业

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2回答

好帮手慕阿满 2020-07-06 19:01:31

我在https://class.imooc.com/course/qadetail/238158这个问答中回复了你，请前去查看。

祝：学习愉快~

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好帮手慕阿满 2020-07-06 16:44:25

同学你好，关于同学的问题：

1、可能是不能识别el表达式，建议在jsp页面的头部增加如下代码：

<%@ page isELIgnored="false" %>

2、修改图书有点问题，按照同学的代码，相当于新增了一个id为原来图书Id的，其他信息都为空的图书。所以点击修改出现新的一行。

这里应该是bookList.jsp页面中，点击修改后，跳转到servlet中，获取该bookId对应的图书信息，然后跳转update.jsp页面中显示。在update.jsp中修改图书信息后，跳转到Servlet中，调用修改图书的方法修改图书信息。

建议同学按照上述步骤重新完成代码。

祝：学习愉快~

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提问者 J_DP #1

第一个按老师的添加进去还是没有用，第二个问题写了但是还是出现这个问题，麻烦老师指点下具体是哪里出错了吗，我有点迷糊

2020-07-06 18:20:02
提问者 J_DP #2

https://class.imooc.com/course/qadetail/238158 老师帮忙移驾看一下

2020-07-06 18:24:56