Question

我目前正在尝试在Android中使用JNI，但每次我在设备上启动应用程序时都会遇到问题，它会崩溃。

这是我的主要活动：

public class MainActivity extends ActionBarActivity {


static {
    System.loadLibrary("native");
}

public native String invokeNativeFunction();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
        .add(R.id.container, new PlaceholderFragment()).commit();
    }

    String hello = invokeNativeFunction();

    new AlertDialog.Builder(this).setMessage(hello).show();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container,
                false);
        return rootView;
    }
}}

我还创建了我的C文件并对其进行了编译：

jstring Java_com_JuniorAndroid_TUNandroid_Hellondk_MainActivity_invokeNativeFunction(JNIEnv* env, jobject javaThis) {

return (*env)->NewStringUTF(env, "Hello from native code!");}

我还有.mk文件：

LOCAL_PATH := $(call my-dir)

    include $(CLEAR_VARS)

    # Here we give our module name and source file(s)
    LOCAL_MODULE    := native
    LOCAL_SRC_FILES := native.c

    include $(BUILD_SHARED_LIBRARY)

但是无论何时我在手机上执行该操作，我都有：

    06-10 15:18:33.326: D/dalvikvm(12806): Trying to load lib /data/data/com.JuniorAndroid.TUNandroid.hellondk/lib/libnative.so 0x413bead0
    06-10 15:18:33.336: D/dalvikvm(12806): Added shared lib /data/data/com.JuniorAndroid.TUNandroid.hellondk/lib/libnative.so 0x413bead0
    06-10 15:18:33.336: D/dalvikvm(12806): No JNI_OnLoad found in /data/data/com.JuniorAndroid.TUNandroid.hellondk/lib/libnative.so 0x413bead0, skipping init
    06-10 15:18:33.506: W/dalvikvm(12806): No implementation found for native Lcom/JuniorAndroid/TUNandroid/hellondk/MainActivity;.invokeNativeFunction ()Ljava/lang/String;
    06-10 15:18:33.516: D/AndroidRuntime(12806): Shutting down VM
    06-10 15:18:33.516: W/dalvikvm(12806): threadid=1: thread exiting with uncaught exception (group=0x40aba210)
    06-10 15:18:33.526: E/AndroidRuntime(12806): FATAL EXCEPTION: main
    06-10 15:18:33.526: E/AndroidRuntime(12806): java.lang.UnsatisfiedLinkError: invokeNativeFunction
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at com.JuniorAndroid.TUNandroid.hellondk.MainActivity.invokeNativeFunction(Native Method)
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at com.JuniorAndroid.TUNandroid.hellondk.MainActivity.onCreate(MainActivity.java:34)
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at android.app.Activity.performCreate(Activity.java:4465)
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1931)
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at android.app.ActivityThread.access$600(ActivityThread.java:127)
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at android.os.Handler.dispatchMessage(Handler.java:99)
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at android.os.Looper.loop(Looper.java:137)
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at android.app.ActivityThread.main(ActivityThread.java:4448)
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at java.lang.reflect.Method.invokeNative(Native Method)
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at java.lang.reflect.Method.invoke(Method.java:511)
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823)
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590)
    06-10 15:18:33.526: E/AndroidRuntime(12806):    at dalvik.system.NativeStart.main(Native Method)

我已经搜索了很多时间来找到答案，但我找不到任何东西。

感谢您的帮助！

Answer 1

您需要将C中的函数声明为JNIEXPORT。如果使用C ++而不是C，你还需要声明它为extern“C”。第一个使它在.so中可见，第二个确保C ++编译器不进行名称修改。

Android，Native开发工具包：找不到本机Lcom的实现

1 个答案: