Monitor download progress with apache http components

I have some big files to download with Apache's Http Components and I want to be able to display some progress info to users in the admin console of my web app. What is the right way to monitor a download in progress using this library? I will create a singleton to manage the ongoing downloads, what I need is a way to inspect the开发者_运维知识库 open connections and find out where they are at any given time.

1. Obtain the Content-Length response header first
2. Get the result as stream and process it byte-by-byte (in batches)
3. Count the bytes processed and show the user the percentage of processed bytes from the total number of bytes (obtained on the 1st step)