I got a G7 Desire recently that didn\'t has Google Map Api Lib in it. When I installed an app that use google map api on my phone, the adb console showed INSTALL_FAILED_MISSING_
You have an Android phone (HTC Desire for Chinese market) that is not Google-branded. This means that there are no Google apps on it: no market, no gmail, no maps, etc..
You need to root your phone and then search for Google apps on various forums. Try http://www.xda-developers.com/
Beware: Google apps on Android are bundled with the phone and the license is only for this phone. Google does not offer this apps for non-google branded phones. All such apps are pirated and as such are illegal. Just so that you know..
P.S. All Google branded devices have "with Google (TM)" written on them. If there is no such sigh than there are no Google apps on this device. Don't be so sure about non-brandname devices sold in China. Anything is possible there.
Download the Google Maps app from the MarketPlace
Unless you are writing an application of your own you don't need to actually have the API. You only need to install Google Maps ( go to the market ) on your phone and all other apps should work with it fine.