在servlet中上传文件时遇到问题

Question

我正在学习 Servlet 中的文件上传教程

我的系统配置是

日食
阿帕奇 Tomcat 8.5
Jdk:1.8

我的index.html(表单代码):

<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<form action="UploadFileServlet" method="post">
    Select a file to upload 
    <input type="file" value="file" name="source"/> 
    <input type="submit" value="Upload"/>
</form>
</body>
</html>

UploadFileServlet.java:

package com.upload;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Paths;
import java.util.Iterator;
import java.util.List;

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 javax.servlet.http.Part;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;


    /**
     * Servlet implementation class UploadFileServlet
     */
    @WebServlet("/UploadFileServlet")
    public class UploadFileServlet extends HttpServlet 
    {
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
        {
            try
            {
            ServletFileUpload sf=new ServletFileUpload(new DiskFileItemFactory());
            List<FileItem> multFileItems=sf.parseRequest(request);
            System.out.println(multFileItems.isEmpty());
            for(FileItem item:multFileItems)
            {
                item.write(new File("E:\aman\"+item.getName()));
            }
            }
            catch(Exception e)
            {
                System.out.println(e);
            }
        }//End of doPost method
    }

我不明白为什么它不起作用。它不会产生任何异常。

预期输出：

我希望此代码上传我在表单中选择的文件到 e:\aman\ 文件夹，但它没有上传任何文件

您可以通过

重现此错误

https://drive.google.com/open?id=1oHnkV5Tmrp2jX8SU6Ilw_EYPWXQbsvv9

Answer 1

我改了 index.html

我加了

enctype="multipart/form-data" 到我的表格

<form action="UploadFileServlet" method="post" enctype="multipart/form-data">

As stated in the HTML specification you have to use the POST method and the enctype attribute of the form has to be set to "multipart/form-data".

在servlet中上传文件时遇到问题

Trouble with uploading file in servlet

java

jsp

servlets

jakarta-ee

file-upload