NativeActivity通过jni调用java层的Android API

1. 继承Nativity，打通native和java层

public class MyNativeActivity extends NativeActivity {

   @Override
    public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
    Log.v("test","oncreate");
    }
 
    public void LoadWebSite(String url){
    Log.v("test", "GetWebPicture, url is:" + url);
    }

}

2. 修改AndroidManifest，让他启动你继承后的MyNativeActivity，而不是原生的NativeActivity 。

把   activity android:name="android.app.NativeActivity"

改成 activity android:name=".MyNativeActivity"

这样，程序启动后运行java层的onCreate，其中super.onCreate(savedInstanceState)会调用到native层的void android_main(struct android_app* state) 入口。

3. 在native code中调用java函数

void getWebPicture(struct android_app* app)
{
    jobject activityInstance = g_app->activity->clazz;
    JavaVM* jvm = g_app->activity->vm;
    JNIEnv *env = NULL;

   (*jvm)->GetEnv(jvm, (void **) &env, JNI_VERSION_1_6);

    if ((*jvm)->AttachCurrentThread(jvm, &env, NULL) < 0)
    {
    LOGE("callback_handler: failed to attach current thread");
    return;
    }

    jclass clazz = (*env)->GetObjectClass(env, activityInstance);
    if (!clazz) {
    LOGE("callback_handler: failed to get WebPicCls class reference");

    (*jvm)->DetachCurrentThread(app->activity->vm);
    return;
    }

    jmethodID methodID = (*env)->GetMethodID(env, clazz, "LoadWebSite", "(Ljava/lang/String;)V");
    if (!methodID) {
    LOGE("callback_handler: failed to get LoadWebSite method ID");
    (*jvm)->DetachCurrentThread(app->activity->vm);
   return;
    }

    jstring url= (*env)->NewStringUTF(env, "http://198.168.1.104");

   (*env)->CallVoidMethod(env, activityInstance, methodID, url);

   (*env)->ReleaseStringUTFChars(env,url,(*env)->GetStringUTFChars(env, url, 0));

   (*jvm)->DetachCurrentThread(jvm);

}