在Activity 的OnSurfaceCreate回调后，表示Surface已经创建成功，可以将surface传到native层player

frameworks/base/media/java/android/media/MediaPlayer.java

    public void setDisplay(SurfaceHolder sh) {
        mSurfaceHolder = sh;
        Surface surface;
        if (sh != null) {
            surface = sh.getSurface();
        } else {
            surface = null;
        }
        _setVideoSurface(surface); //将surface传给 native层
        updateSurfaceScreenOn(); //设置屏幕是否保持打开状态
    }

参数是SurfaceHolder 通过SurfaceHolder去获取Surface，将Surface传给jni

frameworks/base/media/jni/android_media_MediaPlayer.cpp

static void
setVideoSurface(JNIEnv *env, jobject thiz, jobject jsurface, jboolean mediaPlayerMustBeAlive)
{
    sp<MediaPlayer> mp = getMediaPlayer(env, thiz);
    if (mp == NULL) {
        if (mediaPlayerMustBeAlive) {
            jniThrowException(env, "java/lang/IllegalStateException", NULL);
        }
        return;
    }

    decVideoSurfaceRef(env, thiz);

    sp<IGraphicBufferProducer> new_st;
    if (jsurface) {
        sp<Surface> surface(android_view_Surface_getSurface(env, jsurface));
        if (surface != NULL) {
            new_st = surface->getIGraphicBufferProducer();
            if (new_st == NULL) {
                jniThrowException(env, "java/lang/IllegalArgumentException",
                    "The surface does not have a binding SurfaceTexture!");
                return;
            }
            new_st->incStrong((void*)decVideoSurfaceRef);
        } else {
            jniThrowException(env, "java/lang/IllegalArgumentException",
                    "The surface has been released");
            return;
        }
    }

    //将GraphicBufferProducer 的对象new_st 设置给java层的mNativeSurfaceTexture
    //在java的反射中,通过字段获取对象,是通过 public Object get(Object obj) 获取的
    //new_st.get() 获取到new_st的对象，而且对象是static的，如果不是static。如果字段不是静态字段的话,要传入反射类的对象
    env->SetLongField(thiz, fields.surface_texture, (jlong)new_st.get());

    // This will fail if the media player has not been initialized yet. This
    // can be the case if setDisplay() on MediaPlayer.java has been called
    // before setDataSource(). The redundant call to setVideoSurfaceTexture()
    // in prepare/prepareAsync covers for this case.
    mp->setVideoSurfaceTexture(new_st);
}

首先通过surface获取到GraphicBufferProducer， 接着将GraphicBufferProducer设置到MediaPlayer.java 中的mNativeSurfaceTexture，最后调用C++ 层播放器的setVideoSurfaceTexture方法

frameworks/av/media/libmedia/mediaplayer.cpp

status_t MediaPlayer::setVideoSurfaceTexture(
        const sp<IGraphicBufferProducer>& bufferProducer)
{
    ALOGV("setVideoSurfaceTexture");
    Mutex::Autolock _l(mLock);
    if (mPlayer == 0) return NO_INIT;
    return mPlayer->setVideoSurfaceTexture(bufferProducer);
}

mPlayer 是通过binder调用到了MediaPlayerService.cpp中 client内部类的方法

status_t MediaPlayerService::Client::setVideoSurfaceTexture(
        const sp<IGraphicBufferProducer>& bufferProducer)
{
    ALOGV("[%d] setVideoSurfaceTexture(%p)", mConnId, bufferProducer.get());
    sp<MediaPlayerBase> p = getPlayer();
    if (p == 0) return UNKNOWN_ERROR;

    sp<IBinder> binder(IInterface::asBinder(bufferProducer));
    if (mConnectedWindowBinder == binder) {
        return OK;
    }

    sp<ANativeWindow> anw;
    if (bufferProducer != NULL) {
        anw = new Surface(bufferProducer, true /* controlledByApp */);
        status_t err = nativeWindowConnect(anw.get(), "setVideoSurfaceTexture");

        if (err != OK) {
            ALOGE("setVideoSurfaceTexture failed: %d", err);
            // Note that we must do the reset before disconnecting from the ANW.
            // Otherwise queue/dequeue calls could be made on the disconnected
            // ANW, which may result in errors.
            reset();
            
            Mutex::Autolock lock(mLock);
            disconnectNativeWindow_l();
            
            return err;
        }
    }

    // Note that we must set the player's new GraphicBufferProducer before
    // disconnecting the old one.  Otherwise queue/dequeue calls could be made
    // on the disconnected ANW, which may result in errors.
    status_t err = p->setVideoSurfaceTexture(bufferProducer);

    mLock.lock();
    disconnectNativeWindow_l();

    if (err == OK) {
        mConnectedWindow = anw;
        mConnectedWindowBinder = binder;
        mLock.unlock();
    } else {
        mLock.unlock();
        status_t err = nativeWindowDisconnect(
                anw.get(), "disconnectNativeWindow");

        if (err != OK) {
            ALOGW("nativeWindowDisconnect returned an error: %s (%d)",
                    strerror(-err), err);
        }
    }

    return err;
}

主要是将bufferProducer 设置给了NuPlayer，NuPlayer的内容暂时不跟。

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