android-rs-glue | Glue between Rust and Android

Before you can compile for Android, you need to setup your environment. This needs to be done only once per system.
Install rustup.
Run rustup target add <target> for all supported targets to which you want to compile. Building will attempt to build for all supported targets unless the build targets are adjusted via Cargo.toml. rustup target add armv7-linux-androideabi rustup target add aarch64-linux-android rustup target add i686-linux-android rustup target add x86_64-linux-android
Install the Java JRE or JDK (on Ubuntu, sudo apt-get install openjdk-8-jdk).
Download and unzip the Android NDK.
Download and unzip the Android SDK.
Install some components in the SDK: ./android-sdk/tools/bin/sdkmanager "platform-tools" "platforms;android-29" "build-tools;29.0.0".
Install cargo-apk with cargo install cargo-apk.
Set the environment variables NDK_HOME to the path of the NDK and ANDROID_HOME to the path of the SDK.
cargo apk build supports building multiple binaries and examples using the same arguments as cargo build. It will produce an APK for each binary. Android packages for bin targets are placed in target/android-artifacts/<debug|release>/apk. Android packages for example targets are placed in target/android-artifacts/<debug|release>/apk/examples.
The build process works by:. This first step outputs a shared library, and is run once per target architecture. The command then builds the APK using the shared libraries, generated manifest, and tools from the Android SDK. If the C++ standard library is used, it adds the appropriate shared library to the APK. It signs the APK with the default debug keystore used by Android development tools. If the keystore doesn't exist, it creates it using the keytool from the JRE or JDK.
Using rustc to always compile your crate as a shared library by: Creating a custom CMake toolchain file and setting environment variables which expose the appropriate NDK provided build tools for use with the cc and cmake crates. Creating a temporary file in the same directory as your crate root. This temporary file serves as the crate root of the static library. It contains the contents of the original crate root along with an android_main implementation. Compiling a forked version of android_native_app_glue. android_native_app_glue is originally provided by the NDK. It provides the entrypoint used by Android's NativeActivity that calls android_main. Linking using the NDK provided linker.