What is the structure of the Android PackageManagerService?

I would like to know , what are the sequence of steps that happen once t开发者_C百科he user clicks on the "installApp"??

I need to disable the installation of apps(when user tries to install the app by clicking on install), based on certain conditions, how can i do it?? Any suggestions will help.Thank you.

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You have no control over the installation process. If there is an APK, the user can install it, and your code will not be executed until the installation is complete.