Intent.resolveActivity

public ComponentName resolveActivity(@NonNull PackageManager pm) {
    if (mComponent != null) {//如果当前组件不为空，则返回组件，为显式Intent
        return mComponent;
    }
//如果mComponent为空则是隐式Intent,就解析Intent来获得具体是哪个Intent
    ResolveInfo info = pm.resolveActivity(
        this, PackageManager.MATCH_DEFAULT_ONLY);
    if (info != null) {
        return new ComponentName(//组装Intent的组件，提供显式调用
                info.activityInfo.applicationInfo.packageName,
                info.activityInfo.name);
    }

    return null;
}