Upload a file in a separate thread in a java webapp

Question

I need to make a form where users can upload big files (>200Mo). I wanted to launch the uploads in separate threads so users can launch 3-4 uploads and then do something else. My problem is the generated .tmp file is deleted when i run the secondary thread. I use Struts2.

What struts2 gives me:

private String uploadContentType;
private String uploadFileName;
private File upload;

I transfer those information to my thread using its constructor

MyThread thread=new MyThread (sourceName, uploadFileName, upload, user, database);
thread.start();

In the run() method:

System.out.println("Src File name: " + myFile);
System.out.println("Dst File name: " + myFileFileName);

File destFile  =new File(UPLOAD_DIRECTORY, myFileFileName);
FileUtils.copyFile(myFile, destFile);

And the error:

Src Filename:
C:\***myeclipsepath***\upload_1949ed75_1002_4ccf_b198_
25faff66563a_00000003.tmp
Dst File name: books.xml
java.io.FileNotFoundException:    
C:\***myeclipsepath***\upload_1949ed75_1002_4ccf_b198_
25faff66563a_00000003.tmp  (Le fichier spécifié est introuvable)
   at java.io.FileInputStream.open0(Native Method)
   at java.io.FileInputStream.open(Unknown Source)
   at java.io.FileInputStream.<init>(Unknown Source)
   at org.apache.commons.io.FileUtils.doCopyFile(FileUtils.java:1068)
   at org.apache.commons.io.FileUtils.copyFile(FileUtils.java:1021)
   at org.apache.commons.io.FileUtils.copyFile(FileUtils.java:968)
   at bo.threads.MyThread .run(MyThread .java:68)

When i debug step-by-step i see that the .tmp file disappear when i call thread.start().

So how can i upload files on other threads than the main one ?

score 2 · Accepted Answer · edited May 23 '17 at 12:29

Running multiple threads in a WebApp is basically never required and almost always a bad idea.

You are probably not aware that you can upload multiple files concurrently. You can also tweak your configuration settings to allow files with a size higher than the default threshold (both per-file and per-request).

The only thing remaining to accomplish your requirement of letting the user do something else after they started uploading can be achieved by either:

opening the upload page in a new tab, then run a standard submit (user then change previous tab manually)
open the upload action in a new tab with target="_blank" (user then change previous tab manually)
upload through AJAX (but with huge size you might encounter limits and problems).

I'd go with solution n.2.

EDIT

Thank you for your advice, it should work but how can I close automatically the tab in my action ?

There are many ways, for example you can return a JSP consisting of the following content:

<script>
    window.close();
</script>

But consider informing the user of the positive (or negative) outcome of the operation with a more descriptive, non-self-closing page, or (if you close the tab) with a listener of some kind from the other tab (that would be perfect, and that would be a completely new question, so try making this work before).

Thank you for your advice, it should work but how can i close automatically close the tab in my action ? — Erwan C., Aug 04 '15 at 15:09
Ok i'll go with an alert for both sucess and fail and a timed closing script if the operation is successful — Erwan C., Aug 05 '15 at 08:31

Upload a file in a separate thread in a java webapp

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