in the general development of Java Web programs, We usually use localhost or 127.0.0.1来 to access the native Web service, but if we use the same address in the Android emulator to access it, the Android emulator will not be able to access our services properly, why is it? We can understand this: Android is the Linux kernel, including Android itself is an operating system, therefore, At this point we entered the browser in the simulator localhost or 127.0.0.1 represents the Android simulator (Android virtual machine), not your computer, understand? This is why you will report "Web page not available" When you use localhost in the emulator.
So how do you get access to Web apps on your local computer?
in Android, we map the address of our local computer to 10.0.2.2, so we
just need to change the original localhost or 127.0.0.1 to 10.0.2.2. You can access the Web resources on the local computer on the emulator.
Of course, Android apps also don't forget to add Internet permissions to access the network.
Android Emulator Access Tomcat