Just to clarify: from within your app, you can simply refer to the Emulator as "localhost" or 127.0.0.1.
Web traffic is routed through your development machine, so the Emulator's External-IP is whatever External-IP has been assigned to that development machine by your internet-provider. The development machine can always be reached from your device at 10.0.2.2.
If you have multiple Emulators launched, where adb does not work,
unless you pick one by Emulator's Local-IP (like adb -s 192.168.232.2:5555 shell), then:
Just like a real Android device,
In Emulator, swipe down from top-most, to open menu,
In the menu, press and hold on WiFi,
Finally, go to settings of current WiFi-connection,
If you need to refer to your host computer's localhost, such as when you want the emulator client to contact a server running on the same host, use the alias 10.0.2.2 to refer to the host computer's loopback interface. From the emulator's perspective, localhost (127.0.0.1) refers to its own loopback interface.More details: http://developer.android.com/guide/faq/commontasks.html#localhostalias