I believe that temporary files belong in a temporary folder. In your case, you delete the files yourself, but what if there's a bug in the file deletion operation? Or what if there's a server shutdown before the files are deleted? If you write to a temporary folder, there's at least some hope that the files will be cleaned up later (manually or by some process).
Even when an application wishes to store persistent data (i.e. not temporary), I think it still shouldn't be stored in the Tomcat directory, because those directories tend to be deleted or overwritten whenever you deploy a new version of your application (or even install a new version of Tomcat).
Useful methods:
- java.io.File
.createTempFile
- System
.getProperty("java.io.tmpdir")
