Tomcat 6: how to delete temporary files after a web method call has ended?

Question

I have a temporary file with data that's returned as part of a SOAP response via a MTOM binary attachment. I would like to trash it as soon as the method call "ends" (i.e., finishes transferring). What's the best way for me to do this? The best way I can figure out how to do this is to delete them when the session is destroyed, but I'm not sure if there's a more 'immediate' way to do this.

FYI, I'm NOT using Axis, I'm using jax-ws, if that matters.

UPDATE: I'm not sure the answerers are really understanding the issue. I know how to delete a file in java. My problem is this:

@javax.jws.WebService 
public class MyWebService {
...

 @javax.jws.WebMethod 
 public MyFileResult getSomeObject() {
   File mytempfile = new File("tempfile.txt");
   MyFileResult result = new MyFileResult();
   result.setFile(mytempfile);  // sets mytempfile as MTOM attachment

   // mytempfile.delete() iS WRONG
   // can't delete mytempfile because it hasn't been returned to the web service  client
   // yet.  So how do I remove it?

   return result;
 }
}

Solution

I ran into this same problem. The issue is that the JAX-WS stack manages the file. It is not possible to determine in your code when JAX-WS is done with the file so you do not know when to delete it.

In my case, I am using a DataHandler on my object model rather than a file. MyFileResult would have the following field instead of a file field:

private DataHandler handler;

My solution was to create a customized version of FileDataSource. Instead of returning a FileInputStream to read the contents of the file, I return the following extension of FileInputStream:

private class TemporaryFileInputStream extends FileInputStream {
    public TemporaryFileInputStream(File file) throws FileNotFoundException {
        super(file);
    }

    @Override
    public void close() throws IOException {
        super.close();
        file.delete();
    }
}

Essentially the datasource allows reading only once. After the stream is closed, the file is deleted. Since the JAX-WS stack only reads the file once, it works.

The solution is a bit of a hack but seems to be the best option in this case.

Comments

[Jen A]

Sorry, maybe I should have been more specific. At what point can I delete the file? I can't directly in my @WebMethod annotated function because the web method response hasn't be returned yet.

[Jen A]

I like this solution! My hack was to add the file to a session variable, and then to delete the file when the user's session expired. I also put in an an extra check to delete the file in finalize().