hook between downloading and installing application from android market

I ne开发者_开发技巧ed to make an antivirus type thing... for which i want that after downloading and before installing the application i want to check it... how can that be possible...

See this question. You can determine that an app has been installed, but not intervene, within the Android security model (unrooted devices).

Perhaps Google is planning on enabling a more antimalware-friendly API in the future: however, anything that is permitted to do what traditional antivirus packages comes dangerously close to rootkit territory...