Java 超级强悍的Android NDK：获取位置百分比以更新音频进度seekbar

我正在使用Android上播放MP3。我想使用seekbar在文件播放时显示进度。我的计划是在Java端使用Runnable每秒获取播放器的

positionPercent

属性一次，并使用结果更新seekbar。我尝试了许多不同的方法，但都导致了崩溃，要么是一个信号，要么只是模拟器上的一个通知，“不幸的是，xxx已经停止了。”（xxx是应用程序的名称。）

这是我的最新尝试

Java代码：

 private int timeSliderInterval = 1000; // 1 second
 Runnable doUpdateTimeSlider;
 final Handler timeSliderHandler = new Handler();

 void startUpdateTimeSlider() {
     doUpdateTimeSlider.run();
 }

 void stopUpdateTimeSlider() {
     timeSliderHandler.removeCallbacks(doUpdateTimeSlider);
 }

 @Override
 public void onDestroy() {
     super.onDestroy();
     stopUpdateTimeSlider();
 }

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

     doUpdateTimeSlider = new Runnable() {
         @Override
         public void run() {
             updateTimeSlider();
             timeSliderHandler.postDelayed(this, timeSliderInterval);
         }
         void updateTimeSlider() {
             float pp;
             // this is where problems begin!
             pp = getPositionPercent();
             int ppint = (int) (pp*100);
             timeSlider.setProgress(ppint);
         }
     };


private native int getPositionPercent();

C++代码：

 float SuperpoweredExample::getPositionPercent () {
     float pp = 0.01f;
     pp = player1->positionPercent;
     return pp; }

extern "C" JNIEXPORT jint Java_org_irthlingz_ChoirherenceA3_PlayActivity_getPositionPercent(JNIEnv * __unused javaEnvironment, jobject __unused obj) {
    example->getPositionPercent();
}

应用程序构建和启动时不会出错。但是当我到达将执行

SuperpoweredExample:：getPositionPercent

的地方时，它崩溃了

可运行部分本身工作。但是，只要我尝试检索位置百分比，我就会遇到这样或那样的崩溃

还有一件事：如果我将强制转换注释为int，并在其后添加一行：

         int ppint = (int) (pp*100);
         timeSlider.setProgress(ppint);

我仍然得到一个信号。所以这些线在这一点上不是问题

有什么想法吗

这是一个堆栈跟踪：

Signal = SIGILL (signal SIGILL: illegal instruction operand)
javaEnvironment = {JNIEnv * | 0xb4059a80} 0xb4059a80
 [0] = {JNIEnv} 
  functions = {const JNINativeInterface * | 0xb3fb2a40} 0xb3fb2a40
   [0] = {const JNINativeInterface} 
    reserved0 = {void * | 0x0} nil
    reserved1 = {void * | 0x0} nil
    reserved2 = {void * | 0x0} nil
    reserved3 = {void * | 0x0} nil
    GetVersion = {jint (*)(JNIEnv *) | 0xb39d05f5} (libart.so`art::CheckJNI::GetVersion(_JNIEnv*))
    DefineClass = {jclass (*)(JNIEnv *, const char *, jobject, const jbyte *, jsize) | 0xb39d1ad0} (libart.so`art::CheckJNI::DefineClass(_JNIEnv*, char const*, _jobject*, signed char const*, int))
    FindClass = {jclass (*)(JNIEnv *, const char *) | 0xb39d1f8c} (libart.so`art::CheckJNI::FindClass(_JNIEnv*, char const*))
    FromReflectedMethod = {jmethodID (*)(JNIEnv *, jobject) | 0xb39d2c2f} (libart.so`art::CheckJNI::FromReflectedMethod(_JNIEnv*, _jobject*))
    FromReflectedField = {jfieldID (*)(JNIEnv *, jobject) | 0xb39d31b4} (libart.so`art::CheckJNI::FromReflectedField(_JNIEnv*, _jobject*))
    ToReflectedMethod = {jobject (*)(JNIEnv *, jclass, jmethodID, jboolean) | 0xb39d36f0} (libart.so`art::CheckJNI::ToReflectedMethod(_JNIEnv*, _jclass*, _jmethodID*, unsigned char))
    GetSuperclass = {jclass (*)(JNIEnv *, jclass) | 0xb39d23d8} (libart.so`art::CheckJNI::GetSuperclass(_JNIEnv*, _jclass*))
    IsAssignableFrom = {jboolean (*)(JNIEnv *, jclass, jclass) | 0xb39d27f0} (libart.so`art::CheckJNI::IsAssignableFrom(_JNIEnv*, _jclass*, _jclass*))
    ToReflectedField = {jobject (*)(JNIEnv *, jclass, jfieldID, jboolean) | 0xb39d3b50} (libart.so`art::CheckJNI::ToReflectedField(_JNIEnv*, _jclass*, _jfieldID*, unsigned char))
    Throw = {jint (*)(JNIEnv *, jthrowable) | 0xb39d3fb0} (libart.so`art::CheckJNI::Throw(_JNIEnv*, _jthrowable*))
    ThrowNew = {jint (*)(JNIEnv *, jclass, const char *) | 0xb39d44c0} (libart.so`art::CheckJNI::ThrowNew(_JNIEnv*, _jclass*, char const*))
    ExceptionOccurred = {jthrowable (*)(JNIEnv *) | 0xb39d49da} (libart.so`art::CheckJNI::ExceptionOccurred(_JNIEnv*))
    ExceptionDescribe = {void (*)(JNIEnv *) | 0xb39d4dd0} (libart.so`art::CheckJNI::ExceptionDescribe(_JNIEnv*))
    ExceptionClear = {void (*)(JNIEnv *) | 0xb39d5200} (libart.so`art::CheckJNI::ExceptionClear(_JNIEnv*))
    FatalError = {void (*)(JNIEnv *, const char *) | 0xb39d5a30} (libart.so`art::CheckJNI::FatalError(_JNIEnv*, char const*))
    PushLocalFrame = {jint (*)(JNIEnv *, jint) | 0xb39d5e3e} (libart.so`art::CheckJNI::PushLocalFrame(_JNIEnv*, int))
    PopLocalFrame = {jobject (*)(JNIEnv *, jobject) | 0xb39d625d} (libart.so`art::CheckJNI::PopLocalFrame(_JNIEnv*, _jobject*))
    NewGlobalRef = {jobject (*)(JNIEnv *, jobject) | 0xb39d6bd5} (libart.so`art::CheckJNI::NewGlobalRef(_JNIEnv*, _jobject*))
    DeleteGlobalRef = {void (*)(JNIEnv *, jobject) | 0xb39d72d9} (libart.so`art::CheckJNI::DeleteGlobalRef(_JNIEnv*, _jobject*))
    DeleteLocalRef = {void (*)(JNIEnv *, jobject) | 0xb39d729f} (libart.so`art::CheckJNI::DeleteLocalRef(_JNIEnv*, _jobject*))
    IsSameObject = {jboolean (*)(JNIEnv *, jobject, jobject) | 0xb39d7740} (libart.so`art::CheckJNI::IsSameObject(_JNIEnv*, _jobject*, _jobject*))
    NewLocalRef = {jobject (*)(JNIEnv *, jobject) | 0xb39d6b9b} (libart.so`art::CheckJNI::NewLocalRef(_JNIEnv*, _jobject*))
    EnsureLocalCapacity = {jint (*)(JNIEnv *, jint) | 0xb39d7313} (libart.so`art::CheckJNI::EnsureLocalCapacity(_JNIEnv*, int))
    AllocObject = {jobject (*)(JNIEnv *, jclass) | 0xb39d7b90} (libart.so`art::CheckJNI::AllocObject(_JNIEnv*, _jclass*))
    NewObject = {jobject (*)(JNIEnv *, jclass, jmethodID, ...) | 0xb39d867c} (libart.so`art::CheckJNI::NewObject(_JNIEnv*, _jclass*, _jmethodID*, ...))
    NewObjectV = {jobject (*)(JNIEnv *, jclass, jmethodID, va_list) | 0xb39d80a5} (libart.so`art::CheckJNI::NewObjectV(_JNIEnv*, _jclass*, _jmethodID*, char*))
    NewObjectA = {jobject (*)(JNIEnv *, jclass, jmethodID, jvalue *) | 0xb39d86a7} (libart.so`art::CheckJNI::NewObjectA(_JNIEnv*, _jclass*, _jmethodID*, jvalue*))
    GetObjectClass = {jclass (*)(JNIEnv *, jobject) | 0xb39d8c7e} (libart.so`art::CheckJNI::GetObjectClass(_JNIEnv*, _jobject*))
    IsInstanceOf = {jboolean (*)(JNIEnv *, jobject, jclass) | 0xb39d9090} (libart.so`art::CheckJNI::IsInstanceOf(_JNIEnv*, _jobject*, _jclass*))
    GetMethodID = {jmethodID (*)(JNIEnv *, jclass, const char *, const char *) | 0xb39d99b0} (libart.so`art::CheckJNI::GetMethodID(_JNIEnv*, _jclass*, char const*, char const*))
    CallObjectMethod = {jobject (*)(JNIEnv *, jobject, jmethodID, ...) | 0xb39ea042} (libart.so`art::CheckJNI::CallObjectMethod(_JNIEnv*, _jobject*, _jmethodID*, ...))
    CallObjectMethodV = {jobject (*)(JNIEnv *, jobject, jmethodID, va_list) | 0xb39e9fd9} (libart.so`art::CheckJNI::CallObjectMethodV(_JNIEnv*, _jobject*, _jmethodID*, char*))
    CallObjectMethodA = {jobject (*)(JNIEnv *, jobject, jmethodID, jvalue *) | 0xb39e7197} (libart.so`art::CheckJNI::CallObjectMethodA(_JNIEnv*, _jobject*, _jmethodID*, jvalue*))
    CallBooleanMethod = {jboolean (*)(JNIEnv *, jobject, jmethodID, ...) | 0xb39e9f6f} (libart.so`art::CheckJNI::CallBooleanMethod(_JNIEnv*, _jobject*, _jmethodID*, ...))
    CallBooleanMethodV = {jboolean (*)(JNIEnv *, jobject, jmethodID, va_list) | 0xb39e9f05} (libart.so`art::CheckJNI::CallBooleanMethodV(_JNIEnv*, _jobject*, _jmethodID*, char*))
    CallBooleanMethodA = {jboolean (*)(JNIEnv *, jobject, jmethodID, jvalue *) | 0xb39e712d} (libart.so`art::CheckJNI::CallBooleanMethodA(_JNIEnv*, _jobject*, _jmethodID*, jvalue*))
    CallByteMethod = {jbyte (*)(JNIEnv *, jobject, jmethodID, ...) | 0xb39e9e9b} (libart.so`art::CheckJNI::CallByteMethod(_JNIEnv*, _jobject*, _jmethodID*, ...))
    CallByteMethodV = {jbyte (*)(JNIEnv *, jobject, jmethodID, va_list) | 0xb39e9e31} (libart.so`art::CheckJNI::CallByteMethodV(_JNIEnv*, _jobject*, _jmethodID*, char*))
    CallByteMethodA = {jbyte (*)(JNIEnv *, jobject, jmethodID, jvalue *) | 0xb39e70c3} (libart.so`art::CheckJNI::CallByteMethodA(_JNIEnv*, _jobject*, _jmethodID*, jvalue*))
    CallCharMethod = {jchar (*)(JNIEnv *, jobject, jmethodID, ...) | 0xb39e9dc7} (libart.so`art::CheckJNI::CallCharMethod(_JNIEnv*, _jobject*, _jmethodID*, ...))
    CallCharMethodV = {jchar (*)(JNIEnv *, jobject, jmethodID, va_list) | 0xb39e9d5d} (libart.so`art::CheckJNI::CallCharMethodV(_JNIEnv*, _jobject*, _jmethodID*, char*))
    CallCharMethodA = {jchar (*)(JNIEnv *, jobject, jmethodID, jvalue *) | 0xb39e7059} (libart.so`art::CheckJNI::CallCharMethodA(_JNIEnv*, _jobject*, _jmethodID*, jvalue*))
    CallShortMethod = {jshort (*)(JNIEnv *, jobject, jmethodID, ...) | 0xb39e9cf3} (libart.so`art::CheckJNI::CallShortMethod(_JNIEnv*, _jobject*, _jmethodID*, ...))
    CallShortMethodV = {jshort (*)(JNIEnv *, jobject, jmethodID, va_list) | 0xb39e9c89} (libart.so`art::CheckJNI::CallShortMethodV(_JNIEnv*, _jobject*, _jmethodID*, char*))
    CallShortMethodA = {jshort (*)(JNIEnv *, jobject, jmethodID, jvalue *) | 0xb39e6fef} (libart.so`art::CheckJNI::CallShortMethodA(_JNIEnv*, _jobject*, _jmethodID*, jvalue*))
    CallIntMethod = {jint (*)(JNIEnv *, jobject, jmethodID, ...) | 0xb39e9c20} (libart.so`art::CheckJNI::CallIntMethod(_JNIEnv*, _jobject*, _jmethodID*, ...))
obj = {jobject | 0xbfcda6ec} 0xbfcda6ec

---

JNIEXPORT语句需要一个“return”：

而不是我所拥有的：

example->getPositionPercent();

---

当应用程序崩溃时，你有任何堆栈跟踪吗？@kevto我添加了堆栈跟踪。谢谢你的建议。你实现了JNI桥吗？JNIEXPORT诸如此类的东西？@Gabor Szanto-谢谢你的登记！还没有成功。我确实创建了一个基于CrossExample的简化项目，该项目只是尝试返回一个int。这个问题包括github上的一个完整项目：是的，@Gabor Szanto，我实现了JNIEXPORT等。我已经添加了它和“私有本机int getPositionPercent（）；在我的问题中，我之所以知道这一点，是因为那个美丽的人史蒂夫·M.在这里给出了答案：

example->getPositionPercent();