问题
I can access my Web API server from a Windows app without problems. From Android, though, is a different story
Why would that be?
Is "localhost" the wrong thing to use (in the URL)? Should I use the name of the computer instead?
Does the string (passed literally as "http://localhost:28642/api/Departments/GetCount?serialNum=4242") need to be verbatimized?
What is the difference between a Windows app calling a REST method, and an Android app calling the same REST method, that would cause the latter to fail (connection refused)?
回答1:
Referencing "localhost" to refer to your local machine doesn't work on the Android emulator; you need to use a special IP which the emulator will forward on to the host machine. You need to replace localhost with 10.0.2.2, as per this answer.
If you're testing this on a physical device (rather than the emulator) you'll need to use your machines IP on the local network.
来源：https://stackoverflow.com/questions/22798949/why-is-my-web-api-server-refusing-to-accept-calls-from-android