IjkMediaPlayer的mNativeMediaPlayer的设置

2024-01-23 09:52:10

public final class IjkMediaPlayer extends AbstractMediaPlayer {
 @AccessedByNative
 private long mNativeMediaPlayer;
}

@AccessedByNative
意思是通过native代码进行赋值

在IjkMediaPlayer有下面一段代码

  public static void loadLibrariesOnce(IjkLibLoader libLoader) {
        Class var1 = IjkMediaPlayer.class;
        synchronized(IjkMediaPlayer.class) {
            if (!mIsLibLoaded) {
                if (libLoader == null) {
                    libLoader = sLocalLibLoader;
                }

                libLoader.loadLibrary("ijkffmpeg");
                libLoader.loadLibrary("ijksdl");
                libLoader.loadLibrary("ijkplayer");
                mIsLibLoaded = true;
            }

        }
    }

libLoader.loadLibrary("ijksdl");加载sdl库

这句话会执行ijksdl_android_jni.c的JNI_OnLoad 使用了动态注册技术。动态注册可以看我前面写的文章https://blog.csdn.net/qq_15255121/article/details/115243826

JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved)
{
    int retval;
    JNIEnv* env = NULL;

    g_jvm = vm;
    if ((*vm)->GetEnv(vm, (void**) &env, JNI_VERSION_1_4) != JNI_OK) {
        return -1;
    }

    retval = J4A_LoadAll__catchAll(env);
    JNI_CHECK_RET(retval == 0, env, NULL, NULL, -1);

    return JNI_VERSION_1_4;
}

重点我们看J4A_LoadAll__catchAll

int J4A_LoadAll__catchAll(JNIEnv *env)
{
    int ret = 0;

    // load android.os.Build at very beginning
    J4A_LOAD_CLASS(android_os_Build);

#include "j4a/j4a_allclasses.loader.h"

fail:
    return ret;
}

这段代码有意思#include "j4a/j4a_allclasses.loader.h"

用.h定义了一顿代码

J4A_LOAD_CLASS(java_nio_Buffer);
    J4A_LOAD_CLASS(java_nio_ByteBuffer);
    J4A_LOAD_CLASS(java_util_ArrayList);
    J4A_LOAD_CLASS(android_media_AudioTrack);
    J4A_LOAD_CLASS(android_media_MediaCodec);
    J4A_LOAD_CLASS(android_media_MediaFormat);
    J4A_LOAD_CLASS(android_media_PlaybackParams);
    J4A_LOAD_CLASS(android_os_Build);
    J4A_LOAD_CLASS(android_os_Bundle);
    J4A_LOAD_CLASS(tv_danmaku_ijk_media_player_misc_IMediaDataSource);
    J4A_LOAD_CLASS(tv_danmaku_ijk_media_player_misc_IAndroidIO);
    J4A_LOAD_CLASS(tv_danmaku_ijk_media_player_IjkMediaPlayer);

我们重点看

J4A_LOAD_CLASS(tv_danmaku_ijk_media_player_IjkMediaPlayer);

#define J4A_LOAD_CLASS(class__) \
    do { \
        ret = J4A_loadClass__J4AC_##class__(env); \
        if (ret) \
            goto fail; \
    } while (0)

可以知道最后调用的是J4A_loadClass__J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer

我们看下定义

int J4A_loadClass__J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer(JNIEnv *env)
{
    int         ret                   = -1;
    const char *J4A_UNUSED(name)      = NULL;
    const char *J4A_UNUSED(sign)      = NULL;
    jclass      J4A_UNUSED(class_id)  = NULL;
    int         J4A_UNUSED(api_level) = 0;

    if (class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.id != NULL)
        return 0;

    sign = "tv/danmaku/ijk/media/player/IjkMediaPlayer";
    class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.id = J4A_FindClass__asGlobalRef__catchAll(env, sign);
    if (class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.id == NULL)
        goto fail;

    class_id = class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.id;
    name     = "mNativeMediaPlayer";
    sign     = "J";
    class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.field_mNativeMediaPlayer = J4A_GetFieldID__catchAll(env, class_id, name, sign);
    if (class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.field_mNativeMediaPlayer == NULL)
        goto fail;

    class_id = class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.id;
    name     = "mNativeMediaDataSource";
    sign     = "J";
    class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.field_mNativeMediaDataSource = J4A_GetFieldID__catchAll(env, class_id, name, sign);
    if (class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.field_mNativeMediaDataSource == NULL)
        goto fail;

    class_id = class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.id;
    name     = "mNativeAndroidIO";
    sign     = "J";
    class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.field_mNativeAndroidIO = J4A_GetFieldID__catchAll(env, class_id, name, sign);
    if (class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.field_mNativeAndroidIO == NULL)
        goto fail;

    class_id = class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.id;
    name     = "postEventFromNative";
    sign     = "(Ljava/lang/Object;IIILjava/lang/Object;)V";
    class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.method_postEventFromNative = J4A_GetStaticMethodID__catchAll(env, class_id, name, sign);
    if (class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.method_postEventFromNative == NULL)
        goto fail;

    class_id = class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.id;
    name     = "onSelectCodec";
    sign     = "(Ljava/lang/Object;Ljava/lang/String;II)Ljava/lang/String;";
    class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.method_onSelectCodec = J4A_GetStaticMethodID__catchAll(env, class_id, name, sign);
    if (class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.method_onSelectCodec == NULL)
        goto fail;

    class_id = class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.id;
    name     = "onNativeInvoke";
    sign     = "(Ljava/lang/Object;ILandroid/os/Bundle;)Z";
    class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.method_onNativeInvoke = J4A_GetStaticMethodID__catchAll(env, class_id, name, sign);
    if (class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.method_onNativeInvoke == NULL)
        goto fail;

    J4A_ALOGD("J4ALoader: OK: '%s' loaded\n", "tv.danmaku.ijk.media.player.IjkMediaPlayer");
    ret = 0;
fail:
    return ret;
}

typedef struct J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer {
    jclass id;

    jfieldID field_mNativeMediaPlayer;
    jfieldID field_mNativeMediaDataSource;
    jfieldID field_mNativeAndroidIO;
    jmethodID method_postEventFromNative;
    jmethodID method_onSelectCodec;
    jmethodID method_onNativeInvoke;
} J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer;
static J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer;

我们通过上面的函数

sign = "tv/danmaku/ijk/media/player/IjkMediaPlayer";
    class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.id = J4A_FindClass__asGlobalRef__catchAll(env, sign);
    if (class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.id == NULL)
        goto fail;

    class_id = class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.id;
    name     = "mNativeMediaPlayer";
    sign     = "J";
    class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.field_mNativeMediaPlayer = J4A_GetFieldID__catchAll(env, class_id, name, sign);
    if (class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.field_mNativeMediaPlayer == NULL)
        goto fail;

就能知道获取到mNativeMediaPlayer相应的fileId

我们看下mNativeMediaPlayer的值的获取与设置

jlong J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer__mNativeMediaPlayer__get(JNIEnv *env, jobject thiz)
{
    return (*env)->GetLongField(env, thiz, class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.field_mNativeMediaPlayer);
}

jlong J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer__mNativeMediaPlayer__get__catchAll(JNIEnv *env, jobject thiz)
{
    jlong ret_value = J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer__mNativeMediaPlayer__get(env, thiz);
    if (J4A_ExceptionCheck__catchAll(env)) {
        return 0;
    }

    return ret_value;
}

void J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer__mNativeMediaPlayer__set(JNIEnv *env, jobject thiz, jlong value)
{
    (*env)->SetLongField(env, thiz, class_J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer.field_mNativeMediaPlayer, value);
}

void J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer__mNativeMediaPlayer__set__catchAll(JNIEnv *env, jobject thiz, jlong value)
{
    J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer__mNativeMediaPlayer__set(env, thiz, value);
    J4A_ExceptionCheck__catchAll(env);
}

我们看下mNativeMediaPlayer的设置

IjkMediaPlayer ijkMediaPlayer = new IjkMediaPlayer();

我们使用ijikplayer的时候要

IjkMediaPlayer.java

  

public IjkMediaPlayer() {
        this(sLocalLibLoader);
    }

    public IjkMediaPlayer(IjkLibLoader libLoader) {
        this.mWakeLock = null;
        this.initPlayer(libLoader);
    }
private void initPlayer(IjkLibLoader libLoader) {
        loadLibrariesOnce(libLoader);
        initNativeOnce();
        Looper looper;
        if ((looper = Looper.myLooper()) != null) {
            this.mEventHandler = new IjkMediaPlayer.EventHandler(this, looper);
        } else if ((looper = Looper.getMainLooper()) != null) {
            this.mEventHandler = new IjkMediaPlayer.EventHandler(this, looper);
        } else {
            this.mEventHandler = null;
        }

        this.native_setup(new WeakReference(this));
    }

ijkplayer_jni.c

    { "native_setup",           "(Ljava/lang/Object;)V", (void *) IjkMediaPlayer_native_setup },

static void
IjkMediaPlayer_native_setup(JNIEnv *env, jobject thiz, jobject weak_this)
{
    MPTRACE("%s\n", __func__);
    IjkMediaPlayer *mp = ijkmp_android_create(message_loop);
    JNI_CHECK_GOTO(mp, env, "java/lang/OutOfMemoryError", "mpjni: native_setup: ijkmp_create() failed", LABEL_RETURN);

    jni_set_media_player(env, thiz, mp);
    ijkmp_set_weak_thiz(mp, (*env)->NewGlobalRef(env, weak_this));
    ijkmp_set_inject_opaque(mp, ijkmp_get_weak_thiz(mp));
    ijkmp_set_ijkio_inject_opaque(mp, ijkmp_get_weak_thiz(mp));
    ijkmp_android_set_mediacodec_select_callback(mp, mediacodec_select_callback, ijkmp_get_weak_thiz(mp));

LABEL_RETURN:
    ijkmp_dec_ref_p(&mp);
}

static IjkMediaPlayer *jni_set_media_player(JNIEnv* env, jobject thiz, IjkMediaPlayer *mp)
{
    pthread_mutex_lock(&g_clazz.mutex);

    IjkMediaPlayer *old = (IjkMediaPlayer*) (intptr_t) J4AC_IjkMediaPlayer__mNativeMediaPlayer__get__catchAll(env, thiz);
    if (mp) {
        ijkmp_inc_ref(mp);
    }
    J4AC_IjkMediaPlayer__mNativeMediaPlayer__set__catchAll(env, thiz, (intptr_t) mp);

    pthread_mutex_unlock(&g_clazz.mutex);

    // NOTE: ijkmp_dec_ref may block thread
    if (old != NULL ) {
        ijkmp_dec_ref_p(&old);
    }

    return old;
}

#define J4AC_IjkMediaPlayer__mNativeMediaPlayer__set__catchAll J4AC_tv_danmaku_ijk_media_player_IjkMediaPlayer__mNativeMediaPlayer__set__catchAll

这样就设置了mNativeMediaPlayer

码农公寓

相关文章