Multipart transferTo looks for a wrong file address when using createTempFile

Question

I have the following java code in Spring framework to convert a multipart file to a regular file:

    public static File convertToFile(MultipartFile multipart) {         


        

Answer 1

I solved the same issue by adding apache Commons FileUpload component. Hope it helps for you.

1. add pom dependency

    <!-- File Upload -->
    <dependency>
      <groupId>commons-fileupload</groupId>
      <artifactId>commons-fileupload</artifactId>
      <version>1.3.3</version>
    </dependency>

2. add resolver to spring mvc configuration

    @Bean(name = "multipartResolver")
    public CommonsMultipartResolver multipartResolver() {
        CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver();
        multipartResolver.setMaxUploadSize(100000);
        return multipartResolver;
    }

Answer 2

I figured out what I was doing wrong.

I was trying to convert MultipartFile to File outside of the service layer (in another component). Now I do this conversion inside the service layer (but in a separate class) and it's working fine.

Answer 3

So the code looks like this: StandardMultipartHttpServletRequest

public void transferTo(File dest) throws IOException, IllegalStateException {
  this.part.write(dest.getPath());
}

and MultiPartInputStreamParser:

    /**
     * @see javax.servlet.http.Part#write(java.lang.String)
     */
    public void write(String fileName) throws IOException
    {
        if (_file == null)
        {
            _temporary = false;

            //part data is only in the ByteArrayOutputStream and never been written to disk
            _file = new File (_tmpDir, fileName);

So in the case that the file isn't on disk, we will end up with /tmp twice.

I think this is a bug in StandardMultipartHttpServletRequest -- it is passing a path to something which expects a filename.