android jni example

android_jni_example

Android.mk
==========

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)

LOCAL_MODULE_TAGS := tests

LOCAL_SRC_FILES := $(call all-java-files-under, src)

LOCAL_SDK_VERSION := current

LOCAL_PACKAGE_NAME := Test

LOCAL_JNI_SHARED_LIBRARIES := libtest

include $(BUILD_PACKAGE)

include $(call all-makefiles-under,$(LOCAL_PATH))

JNI Android.mk
==========

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)

LOCAL_SRC_FILES = <...>

LOCAL_C_INCLUDES += \
        $(JNI_H_INCLUDE)

LOCAL_STATIC_LIBRARIES += <...>

LOCAL_SHARED_LIBRARIES := 
	libutils \
	liblog \

LOCAL_MODULE := libtest

include $(BUILD_SHARED_LIBRARY)

libtest
==========

#include <jni.h>

extern "C" {
    void test(JNIEnv* env, jobject thiz) {
        ALOGE("test");
    }
}

static JNINativeMethod gMethods[] = {
    { "test","()V", (void*) test}
};

jint JNI_OnLoad(JavaVM* vm, void* reserved)
{
    JNIEnv *env;
    if (vm->GetEnv((void **)&env, JNI_VERSION_1_6)) {
        return JNI_ERR;
    }

    jclass clazz;
    clazz = env->FindClass("com.sunway.test.Test");
    if (clazz == NULL) {
        ALOGE("Native registration unable to find class '%s'", "com.sunway.test.Test");
        return JNI_FALSE;
    }
    
    if (env->RegisterNatives(clazz, gMethods, 1) < 0) {
        ALOGE("RegisterNatives failed for '%s'", "com.sunway.test.Test");
        return JNI_FALSE;
    }

    return JNI_VERSION_1_6;
}

Test.java
==========

public class Test extends Activity
{
    private native void test();
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        System.loadLibrary("test");
        test();
    }
}