MediaPlayer_Analyze-2-JNI

MediaPlayer Analyze - Framework JNI

frameworks\base\media\jni\android_media_MediaPlayer.cpp

static const JNINativeMethod gMethods[] = {
    {"_setDataSource",      "(Ljava/io/FileDescriptor;JJ)V",    (void *)android_media_MediaPlayer_setDataSourceFD},
    {"_setDataSource",      "(Landroid/media/MediaDataSource;)V",(void *)android_media_MediaPlayer_setDataSourceCallback },
    {"_setVideoSurface",    "(Landroid/view/Surface;)V",        (void *)android_media_MediaPlayer_setVideoSurface},
    {"_prepare",            "()V",                              (void *)android_media_MediaPlayer_prepare},
    {"prepareAsync",        "()V",                              (void *)android_media_MediaPlayer_prepareAsync},
    {"_start",              "()V",                              (void *)android_media_MediaPlayer_start},
    {"_stop",               "()V",                              (void *)android_media_MediaPlayer_stop},
    ......
}
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---

一 初始化

1.1 java层接口

native_setup(new WeakReference<MediaPlayer>(this));
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1.2 jni层接口

frameworks\base\media\jni\android_media_MediaPlayer.cpp

static void
android_media_MediaPlayer_native_setup(JNIEnv *env, jobject thiz, jobject weak_this)
{
    ALOGV("native_setup");
    sp<MediaPlayer> mp = new MediaPlayer(); // new C++ MediaPlayer()
    if (mp == NULL) {
        jniThrowException(env, "java/lang/RuntimeException", "Out of memory");
        return;
    }

    // create new listener and give it to MediaPlayer
    sp<JNIMediaPlayerListener> listener = new JNIMediaPlayerListener(env, thiz, weak_this);
    mp->setListener(listener);

    // Stow our new C++ MediaPlayer in an opaque field in the Java object.
    // 保存C++对象到Java对象中
    setMediaPlayer(env, thiz, mp);
}
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二 设置source

2.1 java层接口

    // 网络流调用
            nativeSetDataSource( // 非本地流调用
                MediaHTTPService.createHttpServiceBinderIfNecessary(path, cookies),
                path,
                keys,
                values);
    // 本地流调用
        _setDataSource(fd, offset, length);
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2.2 jni层接口

frameworks\base\media\jni\android_media_MediaPlayer.cpp

static void
android_media_MediaPlayer_setDataSourceAndHeaders(
        JNIEnv *env, jobject thiz, jobject httpServiceBinderObj, jstring path, jobjectArray keys, jobjectArray values) {

    sp<MediaPlayer> mp = getMediaPlayer(env, thiz);

    sp<IMediaHTTPService> httpService;
    if (httpServiceBinderObj != NULL) {
        sp<IBinder> binder = ibinderForJavaObject(env, httpServiceBinderObj);
        httpService = interface_cast<IMediaHTTPService>(binder);
    }

    // 调用native层接口
    status_t opStatus =
        mp->setDataSource(
                httpService,
                pathStr,
                headersVector.size() > 0? &headersVector : NULL);

    // 回调
    process_media_player_call(
            env, thiz, opStatus, "java/io/IOException",
            "setDataSource failed." );
}
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三 准备

3.1 java层接口

        _prepare();
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3.2 jni层接口

frameworks\base\media\jni\android_media_MediaPlayer.cpp

static void
android_media_MediaPlayer_prepare(JNIEnv *env, jobject thiz)
{
    sp<MediaPlayer> mp = getMediaPlayer(env, thiz);
    
    sp<IGraphicBufferProducer> st = getVideoSurfaceTexture(env, thiz);
    mp->setVideoSurfaceTexture(st);

    process_media_player_call( env, thiz, mp->prepare(), "java/io/IOException", "Prepare failed." );
}
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四 开始/恢复播放

4.1 java层接口

        _start();
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4.2 jni层接口

frameworks\base\media\jni\android_media_MediaPlayer.cpp

static void
android_media_MediaPlayer_start(JNIEnv *env, jobject thiz)
{
    ALOGV("start");
    sp<MediaPlayer> mp = getMediaPlayer(env, thiz);
    
    process_media_player_call( env, thiz, mp->start(), NULL, NULL );
}
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五 暂停播放

5.1 java层接口

        _pause();
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5.2 jni层接口

frameworks\base\media\jni\android_media_MediaPlayer.cpp

static void
android_media_MediaPlayer_pause(JNIEnv *env, jobject thiz)
{
    ALOGV("pause");
    sp<MediaPlayer> mp = getMediaPlayer(env, thiz);
    
    process_media_player_call( env, thiz, mp->pause(), NULL, NULL );
}
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六 停止播放

6.1 java层接口

        _stop();
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6.2 jni层接口

frameworks\base\media\jni\android_media_MediaPlayer.cpp

static void
android_media_MediaPlayer_stop(JNIEnv *env, jobject thiz)
{
    ALOGV("stop");
    sp<MediaPlayer> mp = getMediaPlayer(env, thiz);
    
    process_media_player_call( env, thiz, mp->stop(), NULL, NULL );
}
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七 重置

7.1 java层接口

        _reset();
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7.2 jni层接口

frameworks\base\media\jni\android_media_MediaPlayer.cpp

static void
android_media_MediaPlayer_reset(JNIEnv *env, jobject thiz)
{
    ALOGV("reset");
    sp<MediaPlayer> mp = getMediaPlayer(env, thiz);
    
    process_media_player_call( env, thiz, mp->reset(), NULL, NULL );
}
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八 释放

8.1 java层接口

        _release();
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8.2 jni层接口

frameworks\base\media\jni\android_media_MediaPlayer.cpp

static void
android_media_MediaPlayer_release(JNIEnv *env, jobject thiz)
{
    ALOGV("release");
    decVideoSurfaceRef(env, thiz);
    sp<MediaPlayer> mp = setMediaPlayer(env, thiz, 0);
    if (mp != NULL) {
        // this prevents native callbacks after the object is released
        mp->setListener(0);
        mp->disconnect();
    }
}
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