| The libhello app demonstrates calling Go code from a primarily Java app. |
| |
| Starting in Java lets you program against Android's extensive UI |
| libraries in their native language and call into Go for library code |
| (business logic, code shared with a Go server, portable code). |
| |
| The Java entry point to the program is the file |
| src/com/example/hello/MainActivity.java, where the statement |
| |
| Hi.Hello("world"); |
| |
| is a call into Go code. |
| |
| The Go code is in a package called hi, the file is hi/hi.go, and it |
| contains the function Hello: |
| |
| func Hello(name string) { |
| fmt.Printf("Hello, %s!\n", name) |
| } |
| |
| Java language bindings are generated for this package using the gobind |
| tool. There is a user guide for gobind at |
| |
| http://golang.org/x/mobile/cmd/gobind |
| |
| The generated source has been included in the distribution. If you |
| modify the exported interface of package hi, you have to run gobind |
| manually before calling all.bash. |
| |
| Along with the gobind generated source, the app includes a main.go file |
| to define the app entry point. |
| |
| make.bash builds the app, all.bash deploys it. |
| |
| The first step in building the app is to build the native shared |
| library out of the Go code, and place it in |
| libs/armeabi-v7a/libgojni.so. |
| |
| The second step is building the app with the standard Android build |
| system by calling ant debug (also done in make.bash). Two extra Java |
| files are included in the build by make.bash to support the language |
| bindings. This produces an apk ready for running on a device. |
