javafileservletsjakarta-ee

GetParts() returning null in servlet


Hello guys i'm facing a problem with my code, i have a jsp form that send a file into a servlet, and when i try to extract the file using request.getParts() it return null value wheni try to print it to the console, can anyone help me please. here is my code.

my jsp:

 <!DOCTYPE html>
    <html lang="en">
        <head>
            <title>File Upload</title>
            <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        </head>
        <body>
            <form method="POST" action="/PartsServlet" enctype="multipart/form-data" >
                File:
                <input type="file" name="file" id="file" /> <br/>
                Destination:
                <input type="text" value="/tmp" name="destination"/>
                </br>
                <input type="submit" value="Upload" name="upload" id="upload" />
            </form>
        </body>
    </html>

My servlet:

package Servv;

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;

/**
 * Servlet implementation class PartsServlet
 */
@WebServlet("/PartsServlet")
public class PartsServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public PartsServlet() {
        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());
        System.out.println("Get Parts "+request.getPart("file"));
        System.out.println("Get Parts "+request.getPart("destination"));
    }

    /**
     * @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);
    }

}

Solution

  • Add @MultipartConfig annotation. Always parse your request body only once and store it in a list.
    so that one part cannot consume it.

     List<Part> fileParts = request.getParts().stream().filter(part -> "file".equals(part.getName())).collect(Collectors.toList());
        
        for (Part part : fileParts) { 
        
        }
    
    File uploads = new File("/path/to/uploads");
    File file = File.createTempFile("somefilename-", ".ext", uploads);
    
    try (InputStream input = part.getInputStream()) {
        Files.copy(input, file.toPath(), StandardCopyOption.REPLACE_EXISTING);
    }