Question

我正尝试通过根据以下代码设置字节数组参数来通过JNI调用Java方法。

extern "C"
JNIEXPORT void JNICALL
Java_test_example_test_MainActivity_testOnProgress(JNIEnv *env, jobject instance,
                                                   jobject callback) {

    //declare ref java class
    jclass jClassTestCallBack = env->GetObjectClass(callback);

    //declare java method id
    jmethodID jMethodIdOnProgress = env->GetMethodID(jClassTestCallBack,"onProgress","([B)V");

    //check null
    if(jMethodIdOnProgress == 0){
        return;
    }

    jbyteArray result = env->NewByteArray(10);
    env->CallVoidMethod(callback,jMethodIdOnProgress,result);

}

在Java中。

public class MainActivity extends AppCompatActivity {

    private final String TAG = getClass().getSimpleName();

    // Used to load the 'native-lib' library on application startup.
    static {
        System.loadLibrary("native-lib");
    }

    /**
     * A native method that is implemented by the 'native-lib' native library,
     * which is packaged with this application.
     */
    public native void testOnSuccess(TestCallback callback);
    public native void testOnProgress(TestCallback callback);

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

        // Example of a call to a native method
        final TextView tv =  findViewById(R.id.sample_text);

        testOnProgress(new TestCallback() {
            @Override
            public void onSuccess(String msg) {
                Log.i(TAG, "onSuccess: " + msg);
                tv.setText(msg);
            }

            @Override
            public void onProgress(Byte[] data) {
                if(data!=null){
                    Log.i(TAG, "onProgress: " + data.length);
                    tv.setText("onProgress: data size " + data.length);
                }

            }
        });
    }

}

我不明白如何在GetMethodID中正确声明ByteArray参数，但这是我的日志。

08-28 14:08:49.702 3015-3015/? E/AndroidRuntime: FATAL EXCEPTION: main
        Process: test.example.test, PID: 3015
        java.lang.NoSuchMethodError: no non-static method "Ltest/example/test/MainActivity$1;.onProgress([B)V"
    at test.example.test.MainActivity.testOnProgress(Native Method)
    at test.example.test.MainActivity.onCreate(MainActivity.java:25)
    at android.app.Activity.performCreate(Activity.java:6915)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1123)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2746)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2864)
    at android.app.ActivityThread.-wrap12(ActivityThread.java)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1567)
    at android.os.Handler.dispatchMessage(Handler.java:105)
    at android.os.Looper.loop(Looper.java:156)
    at android.app.ActivityThread.main(ActivityThread.java:6523)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:942)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:832)
    08-28 14:08:49.726 3015-3015/? I/Process: Sending signal. PID: 3015 SIG: 9

但是字符串没有问题。它可以正常工作。这是字符串的一部分。

extern "C"
JNIEXPORT void JNICALL
Java_test_example_test_MainActivity_testOnSuccess(JNIEnv *env, jobject instance, jobject callback) {

    //declare ref java class
    jclass jClassTestCallBack = env->GetObjectClass(callback);

    //declare java method id
    jmethodID jMethodIdOnSuccess = env->GetMethodID(jClassTestCallBack,"onSuccess","(Ljava/lang/String;)V");

    //check null
    if(jMethodIdOnSuccess == 0){
        return;
    }

    env->CallVoidMethod(callback,jMethodIdOnSuccess,env->NewStringUTF("Callback Success!!"));

}

谢谢。

EDITE ：这是我的TestCallBack类，以获取更多信息。

public interface TestCallback {

    void onSuccess(String msg);

    void onProgress(Byte[] data);

}

Answer 1

[B的意思是byte[]，即原始类型byte的数组。

您的onProgress方法采用Byte类的数组，这不是一回事。

您可以：

更改TestCallback的声明，以使onProgress取byte[]。

或

更改您的GetMethodID通话，使其使用正确的签名([Ljava/lang/Byte;)V。这可能需要更改然后尝试调用该方法的任何代码。

无法在JNI中将GetMethodID与字节数组参数一起使用

1 个答案: