出现个空指针异常
来源：6-2 项目作业
Mr__Gao
2019-09-01 11:52:19
package com.imooc.web.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.mainclass.Book;
import com.imooc.utils.UploadUtils;
@WebServlet("/addBookServlet")
public class addBookServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public addBookServlet() {
super();
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
Map<String,String> map=new HashMap<String,String>();
//创建磁盘文件项工厂
DiskFileItemFactory diskFileItemFactory=new DiskFileItemFactory();
//创建核心解析类
ServletFileUpload fileUpload=new ServletFileUpload(diskFileItemFactory);
//解析请求对象，将请求分成几个部分FileItem
try {
List<FileItem> list=fileUpload.parseRequest(request);
//遍历集合，获得各个部分的对象
for(FileItem fileItem:list) {
if(fileItem.isFormField()) {
String name=fileItem.getName();
String value=fileItem.getString("UTF-8");
map.put(name, value);
}else {
String fileName=fileItem.getName();
String uuidFileName=UploadUtils.getUuidFileName(fileName);
InputStream is=fileItem.getInputStream();
String path=getServletContext().getRealPath("/upload");
String url= path+"\\"+uuidFileName;
map.put("path", request.getContextPath()+"/upload"+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 (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Book book=new Book();
book.setBookId(map.get("bookId"));
book.setBookName(map.get("bookName"));
book.setCategoryBook(map.get("categoryId"));
book.setPrice(Float.parseFloat(map.get("bookPrice")));
book.setDescription(map.get("remarks"));
book.setPath(map.get("path"));
response.sendRedirect(request.getContextPath()+"/bookList.jsp");
}
}显示错误在book.setPrice(Float.parseFloat(map.get("bookPrice")));
我设置的price是float
写回答
3回答
-
好帮手慕柯南
2019-09-01
同学你好！
获取非文件项的name时，应该使用fileItem.getFieldName();同学这里使用了fileItem.getName()
如果我都回答解决了你的疑惑，请采纳，祝学习愉快~
0 -
Mr__Gao
提问者
2019-09-01
我输出了一下map，结果显示的是
在map中，value的值存在，key全是null
0 -
Mr__Gao
提问者
2019-09-01
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <% String loginUser=(String)request.getSession().getAttribute("loginUser"); %> <!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>新建图书信息</title> <link rel="stylesheet" href="css/bootstrap.min.css"> <link rel="stylesheet" href="css/add.css"> </head> <body> <nav class="navbar navbar-default"> <div class="container"> <div class="navbar-header"> <a class="navbar-brand" href="/dept/list.do"> 图书信息管理 </a> </div> </div> </nav> <div class="container"> <div class="jumbotron"> <h1>Hello, <%=loginUser%>!</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> <div class="page-header"> <h3><small>新建</small></h3> </div> <form class="form-horizontal" action="${pageContext.request.contextPath}/addBookServlet" method="post" enctype="multipart/form-data"> <div class="form-group"> <label for="name" class="col-sm-2 control-label">图书编号 ：</label> <div class="col-sm-8"> <input name="bookId" class="form-control" id="bookId"> </div> </div> <div class="form-group"> <label for="name" class="col-sm-2 control-label">图书名称 ：</label> <div class="col-sm-8"> <input name="bookName" class="form-control" id="bookName"> </div> </div> <div class="form-group"> <label for="categoryId" class="col-sm-2 control-label">分类 ：</label> <select id="categoryId" name="categoryId" class="col-sm-2 form-control" style="width: auto;margin-left: 15px"> <c:forEach items="${sessionScope.categoryList}" var="cList" varStatus="idx"> <option value="${cList.categoryId}" selected="">${cList.categoryName}</option> </c:forEach> <!-- 下拉列表的内容要从分类中进行读取，value值是分类id --> </select> </div> <div class="form-group"> <label for="name" class="col-sm-2 control-label">价格 ：</label> <div class="col-sm-8"> <input name="bookPrice" class="form-control" id="bookPrice"> </div> </div> <div class="form-group" > <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 class="form-group"> <label for="name" class="col-sm-2 control-label">备注 ：</label> <div class="col-sm-8"> <input name="remarks" class="form-control" id="remarks"> </div> </div> <div class="form-group"> <div class="col-sm-offset-2 col-sm-10"> <button type="submit" class="btn btn-primary">保存</button> </div> </div> </form> </div> <footer class="text-center" > copy@imooc </footer> </body> </html>这是addbook。jsp
我得到的全是空的数值，在普通项中。id，name什么的在控制台输出的map.get（“”）；都是空
0
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