Call Go Function from Java with JNA Demo

With the help of JNA, we can call functions defined by GO from Java.

cd go
go build -buildmode=c-shared -o awesome.so awesome.go

If succeed, you will see awesome.h and awesome.so generated, both of them are very important. awesome.h is used to read the definition of the generated functions and you can define the corresponding structure in Java code. awesome.so is used for calling.

If there is any message shown in the console, there probably be something wrong.

Then run Hello.java (from IDE)

Notice

1. In go file, we must declared import "C". Since IDEA will auto remove unused imported lib, we have to use //// formatter: off/on around it to keep it. Also note we have to use //// instead of // to make go build work
2. In go file, we must use //export MyFuncName to export the functions we want to call from Java. Note it must be //export, there is no spaces between // and export.
3. In go file, the package must be main, and there is a function main
4. We can use nm awesome.so | grep Multiply to verify if the required function is exported
5. We can't return or pass string from Go code, instead, we should use *C.char
6. We can't return or pass byte[] from Go code, instead, we should use unsafe.Pointer

You must be very careful about the advices here.

Resources

• https://github.com/java-native-access/jna
• https://golang.org/cmd/cgo/
• https://github.com/vladimirvivien/go-cshared-examples