[EDIT] 2015-10-15: Now apache provides jar for android (currently 18.104.22.168). Also if you are targeting Android API 23 and newer you can use packages for Android maintained by Marek Sebera (currently 22.214.171.124).
[EDIT] This publication and method are old and deprecated. Please use http://code.google.com/p/httpclientandroidlib/ instead.
If you ended up here that is probably because you hit a bug in the built-in HttpClient library which is not just old, it is beta quality (httpclient-4.0-beta1.jar). Strangely enough there is no hope that Android team will update it soon (also this is impossible without breaking backward compatibility…).
Fear not, there is a remedy.
Sadly we cannot replace the build-in library nor just add newer version but we can "trick" the system and move the library in another namespace in order to avoid conflict with the built-in lib.
The quick solution: here is an zip file containing all the required files (JARs converted using "ogrelab-" namespace prefix). Jump directly to step 7 in the "thorough" solution bellow.
The thorough solution:
1. Download JarJar -- this is the tool which we will use to move the classes in new namespace
3. Create a temporary dir somewhere like tmp_httpclient for example find following Jars and copy them into the temp dir (versions may differ):