Android万能音频播放器08-添加播放器出错回调

如果出错，要把出错信息传给应用层，告诉开发者出错信息，然后做相应处理，出错回调：

void onError(int code, String msg);

在出错回调里面回收资源，并添加变量避免重复调用stop方法。

回调Listener方法：

public interface JfOnErrorListener {
    void onError(int code,String msg);
}

设置回调：

private JfOnErrorListener jfOnErrorListener;

public void setJfOnErrorListener(JfOnErrorListener jfOnErrorListener) {
    this.jfOnErrorListener = jfOnErrorListener;
}

//供C++调用
public void onCallError(int code,String msg){
    if (jfOnErrorListener != null) {
        jfOnErrorListener.onError(code,msg);
    }
}

C++调用Java方法：

jmid_error = env->GetMethodID(jclz,"onCallError","(ILjava/lang/String;)V");

void JfCallJava::onCallError(int threadType, int code, char *msg) {
    if (threadType == MAIN_THREAD){
        jstring jmsg = jniEnv->NewStringUTF(msg);
        jniEnv->CallVoidMethod(jobj,jmid_error,code,jmsg);
        jniEnv->DeleteLocalRef(jmsg);
    } else if (threadType == CHILD_THREAD){
        JNIEnv *jniEnv;
        if (javaVM->AttachCurrentThread(&jniEnv,0) != JNI_OK){
            if (LOG_DEBUG) {
                LOGE("GET CHILD THREAD JNIENV ERROR");
                return;
            }
        }
        jstring jmsg = jniEnv->NewStringUTF(msg);
        jniEnv->CallVoidMethod(jobj,jmid_error,code,jmsg);
        jniEnv->DeleteLocalRef(jmsg);
        javaVM->DetachCurrentThread();
    }
}

在出错的地方调用，例如：

void JfFFmpeg::decodeAudioThread() {
    pthread_mutex_lock(&init_mutex);
    av_register_all();
    avformat_network_init();

    pAFmtCtx = avformat_alloc_context();

    pAFmtCtx->interrupt_callback.callback = avformat_callback;
    pAFmtCtx->interrupt_callback.opaque = this;

    if (avformat_open_input(&pAFmtCtx,url,NULL,NULL) != 0){
        if (LOG_DEBUG){
            LOGE("open url file error url === %s",url);
            callJava->onCallError(CHILD_THREAD,401,"open url file error url");
        }
        exit = true;
        pthread_mutex_unlock(&init_mutex);
        return;
    }

    if (avformat_find_stream_info(pAFmtCtx,NULL) < 0){
        if (LOG_DEBUG){
            LOGE("find stream info error url === %s",url);
            callJava->onCallError(CHILD_THREAD,402,"find stream info error url");
        }
        exit = true;
        pthread_mutex_unlock(&init_mutex);
        return;
    }

    for (int i = 0; i < pAFmtCtx->nb_streams; i++) {
        if (pAFmtCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
            if (audio == NULL) {
                audio = new JfAudio(playStatus,pAFmtCtx->streams[i]->codecpar->sample_rate,callJava);
                audio->streamIndex = i;
                audio->codecpar = pAFmtCtx->streams[i]->codecpar;
                audio->duration = pAFmtCtx->duration / AV_TIME_BASE;//单位是秒
                audio->time_base = pAFmtCtx->streams[i]->time_base;
            }
        }
    }

    AVCodec *dec = avcodec_find_decoder(audio->codecpar->codec_id);
    if (!dec){
        if (LOG_DEBUG){
            LOGE("FIND DECODER ERROR");
            callJava->onCallError(CHILD_THREAD,403,"FIND DECODER ERROR");
        }
        exit = true;
        pthread_mutex_unlock(&init_mutex);
        return;
    }

    audio->pACodecCtx = avcodec_alloc_context3(dec);
    if (!audio->pACodecCtx){
        if (LOG_DEBUG){
            LOGE("avcodec_alloc_context3 ERROR");
            callJava->onCallError(CHILD_THREAD,404,"avcodec_alloc_context3 ERROR");
        }
        exit = true;
        pthread_mutex_unlock(&init_mutex);
        return;
    }

    if (avcodec_parameters_to_context(audio->pACodecCtx,audio->codecpar)){//将解码器中信息复制到上下文当中
        if (LOG_DEBUG){
            LOGE("avcodec_parameters_to_context ERROR");
            callJava->onCallError(CHILD_THREAD,405,"avcodec_parameters_to_context ERROR");
        }
        exit = true;
        pthread_mutex_unlock(&init_mutex);
        return;
    }

    if (avcodec_open2(audio->pACodecCtx,dec,NULL) < 0){
        if (LOG_DEBUG){
            LOGE("avcodec_open2 ERROR");
            callJava->onCallError(CHILD_THREAD,406,"avcodec_open2 ERROR");
        }
        exit = true;
        pthread_mutex_unlock(&init_mutex);
        return;
    }

    if (callJava != NULL){
        if (playStatus != NULL && !playStatus->exit){
            callJava->onCallPrepared(CHILD_THREAD);
        } else {
            exit = true;
        }
    }
    pthread_mutex_unlock(&init_mutex);
}

在出错的时候要释放资源，调用stop方法，并添加变量避免重复调用stop方法。将变量nexit的初始值设为true，调用Java_com_example_myplayer_player_JfPlayer_n_1stop时，将nexit设为false，一直到资源释放完毕，再将nexit设为true，如果资源还没释放完毕，再次调用Java_com_example_myplayer_player_JfPlayer_n_1stop，此时nexit == false，则return，防止重复调用！

bool nexit = true;

extern "C"
JNIEXPORT void JNICALL
Java_com_example_myplayer_player_JfPlayer_n_1stop(JNIEnv *env, jobject instance) {

    if (!nexit){
        return;
    }
    // TODO
    nexit = false;
    if (ffmpeg != NULL){
        ffmpeg->release();
        delete(ffmpeg);
        ffmpeg = NULL;

        if (callJava != NULL){
            delete(callJava);
            callJava = NULL;
        }
        if (playStatus != NULL){
            delete(playStatus);
            playStatus = NULL;
        }
    }
    nexit = true;
}