Android源码－－listAudioPorts调用过程

AudioService.java
private void configureHdmiPlugIntent(Intent intent, int state) {
    ArrayList<AudioPort> ports = new ArrayList<AudioPort>();
    int[] portGeneration = new int[1];
    int status = AudioSystem.listAudioPorts(ports, portGeneration);
}

AudioService.java
// declare native method
public static native int listAudioPorts(ArrayList<AudioPort> ports, int[] generation);

android_media_AudioSystem.cpp
// JNI call
static jint android_media_AudioSystem_listAudioPorts(JNIEnv *env, jobject clazz, jobject jPorts, jintArray jGeneration) {
    unsigned int numPorts;
    struct audio_port *nPorts = NULL;
    do {
        numPorts = 0;
        // get numPorts generation1
        AudioSystem::listAudioPorts(AUDIO_PORT_ROLE_NONE, AUDIO_PORT_TYPE_NONE, &numPorts, NULL, &generation1);