integrate version control with java/j2ee web based application

we have a requirement to provide versioning(like version control) to the files uploaded to our application which is java/j2ee web based. We support files to upload/download to the application. Users frequently do the changes to the file by downloading from my appln and modify them, then upload back to the application. as of now we are just overriding the existing file content with newly uploaded content. now we want to maintain the version for each upload to the application.

We need to mantain the version to the files uploaded. see the diff of the different versions and preview of the file selected.

Please let me if there are any third party tools available/rea开发者_如何学Cdy to use in our application, which can easily integrate with java/j2ee env.

i googled few sites and found Drupal or Joomla can do this but not found the exact integration docs for this implementation.

share any useful information to achieve this.

at last i have used GIT version control which is available in unix/linux systems. I have personalized the commands to support this.