http - Java server side sending file with resume support?

Question

I am trying to allow my java server to transfer a file where a web browser can download.

However, I want the browser if they pause and resume the file transfer to work and not start the download all over again.

Anyone know java code for the server side to fix this issue?

Answer 1

There are two parts to supporting resumable downloads:

• Your response needs to return the Accept-Ranges and Content-Range headers
• You need to write code that can then handle the HTTP Range headers and If-Range to know where a client needs to resume

If you're serving up a static resource your best bet is to use a proxy server, like Apache, to handle the download. If a proxy server isn't an option then you can probably find a Servlet that is bundled with your app server; for example, Tomcat has as DefaultServlet. The downside to this option is that it creates a hard dependency between your application and the application server, which may not be acceptable.

If you decide to roll your own I recommend taking a look at Apache's HTTP Components. It's a nice API that makes working with HTTP requests and responses much easier.