Auto install Android app

When I download a apk file I need to first save it before I can install. Is there anyway to dirctly install it without saving? Do I need to make any changes in the AndroidMa开发者_StackOverflow中文版nifest.xml?

It think what manifest file hasn't any power here. It is up to OS to do this. And it think (as a user) what download must not lead to auto installation of downloaded program.

AFAIK, an app is not extracted when it is installed, but the whole APK reacts as the self contained application. Thus, you must keep the APK in order to use the application. And if you're keeping it, then downloading it is the only option.