Crate jni_min_helper

Minimal helper for jni-rs, supporting dynamic proxies, Android dex embedding and broadcast receiver. Used for calling Java code from Rust.

jni is re-exported here for the user to import jni functions, avoiding version inconsistency between jni and this crate.

This crate uses ndk_context::AndroidContext on Android, usually initialized by android_activity. Examples for Android are provided in the crate page.

Please make sure you are viewing documentation generated for your target.

Re-exports

pub use jni;

Structs

BroadcastReceiver

Handles android.content.BroadcastReceiver object backed by JniProxy.

BroadcastWaiter

Waits for intents received by the managed BroadcastReceiver.

JniClassLoader

Runtime class data loader. Wraps a global reference of java.lang.ClassLoader.

JniProxy

Java dynamic proxy with an invocation handler backed by the Rust closure.

Traits

AutoLocalGlobalize

Converts an AutoLocal<'_> to an GlobalRef.

JObjectAutoLocal

Used for calling jni_clear_ex() and turning an owned JObject<'_> reference (which leaks memory on dropping in a Rust main thread permanently attached to the JVM) into an AutoLocal which deletes the reference from the environment on dropping. Works with android_activity. Note that borrowed references (&JObject<'_>) doesn’t cause memory leak.

JObjectGet

Gets the value from the Java object; calls jni_clear_ex() for an error.

JObjectNew

Creates the Java object (wrapper) for the Rust value.

JValueGenGet

Gets the value returned from the Java method; calls jni_clear_ex() for an error.

Functions

android_api_level

Gets the API level (SDK version) of the current Android OS.

android_app_name

Gets the raw name of the current Android application, parsed from the package name.

android_app_package_name

Gets the package name of the current Android application.

android_context

Gets the current android.content.Context, usually a reference of NativeActivity. This depends on crate ndk_context.

block_for_timeout

Convenient blocker for asynchronous functions, based on futures_lite and futures_timer. Warning: Blocking in the android_main() thread will block the future’s completion if it depends on event processing in this thread (check your glue crate like android_activity).

jni_attach_permanently

Calls jni_get_vm() and tries attaching the current thread to the JVM permanently, in order to make jni_with_env faster. Does nothing and returns false if the thread is currently attached (this behaviour is determined by jni-rs).

jni_clear_ex

It calls JNIEnv::exception_clear() which is needed for handling Java exceptions, Not clearing it may cause the native program to crash on the next JNI call. Heavily used inside this crate, with Result::map_err().

jni_clear_ex_ignore

It is the same as jni_clear_ex_silent() without storing the exception for jni_last_cleared_ex().

jni_clear_ex_silent

It is the same as jni_clear_ex() without printing error information. Use it with Result::map_err() prior to functions from this crate to avoid error printing.

jni_get_vm^⚠

Gets the JavaVM from current Android context.

jni_last_cleared_ex

Takes away the stored reference of java.lang.Throwable of the last Java exception cleared inside this crate (current thread).

jni_with_env

Workaround for https://github.com/jni-rs/jni-rs/issues/558. Calls jni_get_vm(), attaches the current thread to the JVM and executes the closure. The thread may be dettached if it has not been attached previously.