今天來看看AudioEffect中enable相關的介面。


*****************************************原始碼*************************************************

    //Test case 1.3: test getEnabled() failure when called on released effect
    @LargeTest
    public void test1_3GetEnabledAfterRelease() throws Exception {
        boolean result = false;
        String msg = "test1_3GetEnabledAfterRelease()";


        try {
            AudioEffect effect = new AudioEffect(AudioEffect.EFFECT_TYPE_EQUALIZER,
                    AudioEffect.EFFECT_TYPE_NULL,
                    0,
                    0);
            assertNotNull(msg + ": could not create AudioEffect", effect);
            effect.release();
            try {
                effect.getEnabled();
            } catch (IllegalStateException e) {
                result = true;
            }
        } catch (IllegalArgumentException e) {
            msg = msg.concat(": Equalizer not found");
        } catch (UnsupportedOperationException e) {
            msg = msg.concat(": Effect library not loaded");
        }
        assertTrue(msg, result);
    }
 

**********************************************************************************************
原始碼路徑：
frameworks\base\media\tests\mediaframeworktest\src\com\android\mediaframeworktest\functional\MediaAudioEffectTest.java


#######################說明################################

    //Test case 1.3: test getEnabled() failure when called on released effect
    @LargeTest
    public void test1_3GetEnabledAfterRelease() throws Exception {
        boolean result = false;
        String msg = "test1_3GetEnabledAfterRelease()";


        try {
            AudioEffect effect = new AudioEffect(AudioEffect.EFFECT_TYPE_EQUALIZER,
                    AudioEffect.EFFECT_TYPE_NULL,
                    0,
                    0);
            assertNotNull(msg + ": could not create AudioEffect", effect);
            effect.release();
// ++++++++++++++++++++++++++++++release++++++++++++++++++++++++++++++++++
    /**
     * Releases the native AudioEffect resources. It is a good practice to
     * release the effect engine when not in use as control can be returned to
     * other applications or the native resources released.
     */
    public void release() {
        synchronized (mStateLock) {
            native_release();
// ++++++++++++++++++++++++++++++android_media_AudioEffect_native_release++++++++++++++++++++++++++++++++++
static void android_media_AudioEffect_native_release(JNIEnv *env,  jobject thiz) {


    // do everything a call to finalize would
// 刪除建立AudioEffect時，建立的物件
    android_media_AudioEffect_native_finalize(env, thiz);
// ++++++++++++++++++++++++++++++android_media_AudioEffect_native_finalize++++++++++++++++++++++++++++++++++
static void android_media_AudioEffect_native_finalize(JNIEnv *env,  jobject thiz) {
    LOGV("android_media_AudioEffect_native_finalize jobject: %x\n", (int)thiz);


    // delete the AudioEffect object
    AudioEffect* lpAudioEffect = (AudioEffect *)env->GetIntField(
        thiz, fields.fidNativeAudioEffect);
// 此處刪除了lpAudioEffect
// getEnabled的時候會呼叫lpAudioEffect的介面，所以release後再getEnabled會產生異常
    if (lpAudioEffect) {
        LOGV("deleting AudioEffect: %x\n", (int)lpAudioEffect);
        delete lpAudioEffect;
    }


    // delete the JNI data
    AudioEffectJniStorage* lpJniStorage = (AudioEffectJniStorage *)env->GetIntField(
        thiz, fields.fidJniData);
    if (lpJniStorage) {
        LOGV("deleting pJniStorage: %x\n", (int)lpJniStorage);
        delete lpJniStorage;
    }
}
// ------------------------------android_media_AudioEffect_native_finalize----------------------------------
    // + reset the native resources in the Java object so any attempt to access
    // them after a call to release fails.
    env->SetIntField(thiz, fields.fidNativeAudioEffect, 0);
    env->SetIntField(thiz, fields.fidJniData, 0);
}
// ------------------------------android_media_AudioEffect_native_release----------------------------------
            mState = STATE_UNINITIALIZED;
        }
    }
// ------------------------------release----------------------------------
            try {
                effect.getEnabled();
// ++++++++++++++++++++++++++++++++getEnabled++++++++++++++++++++++++++++++++
    /**
     * Returns effect enabled state
     *
     * @return true if the effect is enabled, false otherwise.
     * @throws IllegalStateException
     */
    public boolean getEnabled() throws IllegalStateException {
        checkState("getEnabled()");
        return native_getEnabled();
// ++++++++++++++++++++++++++++++android_media_AudioEffect_native_getEnabled++++++++++++++++++++++++++++++++++
static jboolean
android_media_AudioEffect_native_getEnabled(JNIEnv *env, jobject thiz)
{
    // retrieve the AudioEffect object
    AudioEffect* lpAudioEffect = (AudioEffect *)env->GetIntField(
        thiz, fields.fidNativeAudioEffect);


    if (lpAudioEffect == NULL) {
        jniThrowException(env, "java/lang/IllegalStateException",
            "Unable to retrieve AudioEffect pointer for getEnabled()");
        return false;
    }


    return (jboolean)lpAudioEffect->getEnabled();
// ++++++++++++++++++++++++++++AudioEffect::getEnabled++++++++++++++++++++++++++++++++++++
bool AudioEffect::getEnabled() const
{
// mEnabled在函式AudioEffect::set中被賦值：mEnabled = (volatile int32_t)enabled;


// enabled產生於對函式AudioFlinger::createEffect的呼叫
//    iEffect = audioFlinger->createEffect(getpid(), (effect_descriptor_t *)&mDescriptor,
//            mIEffectClient, priority, output, mSessionId, &mStatus, &mId, &enabled);


// 又將地址傳給了函式AudioFlinger::PlaybackThread::createEffect_l
        // create effect on selected output trhead
//        handle = thread->createEffect_l(client, effectClient, priority, sessionId,
//                &desc, enabled, &lStatus);


// 呼叫函式AudioFlinger::EffectModule::isEnabled
//            *enabled = (int)effect->isEnabled();
// ++++++++++++++++++++++++++++AudioFlinger::EffectModule::isEnabled++++++++++++++++++++++++++++++++++++
bool AudioFlinger::EffectModule::isEnabled()
{
// EffectModule建構函式中會將mState設為IDLE
// 函式updateState和函式setEnabled都會改變mState。
// 函式AudioFlinger::EffectChain::process_l會呼叫函式updateState來更新狀態
    switch (mState) {
    case RESTART:
    case STARTING:
    case ACTIVE:
        return true;
    case IDLE:
    case STOPPING:
    case STOPPED:
    default:
        return false;
    }
}
// ----------------------------AudioFlinger::EffectModule::isEnabled------------------------------------
    return (mEnabled != 0);
}
// ----------------------------AudioEffect::getEnabled------------------------------------
}
// ------------------------------android_media_AudioEffect_native_getEnabled----------------------------------
    }
// --------------------------------getEnabled--------------------------------
            } catch (IllegalStateException e) {
                result = true;
            }
        } catch (IllegalArgumentException e) {
            msg = msg.concat(": Equalizer not found");
        } catch (UnsupportedOperationException e) {
            msg = msg.concat(": Effect library not loaded");
        }
        assertTrue(msg, result);
    }
 

###########################################################


&&&&&&&&&&&&&&&&&&&&&&&總結&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
release時會刪除native中建立的AudioEffectJniStorage物件和AudioEffect物件。
getEnabled是根據EffectModule的狀態返回的。
release之後，再呼叫getEnabled函式，由於AudioEffect物件已被刪除，所以會產生異常。
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