AppCompatDrawableManager.java 文件源码

private boolean addCachedDelegateDrawable(@NonNull final Context context, final long key,
        @NonNull final Drawable drawable) {
    final ConstantState cs = drawable.getConstantState();
    if (cs != null) {
        synchronized (mDelegateDrawableCacheLock) {
            LongSparseArray<WeakReference<ConstantState>> cache
                    = mDelegateDrawableCaches.get(context);
            if (cache == null) {
                cache = new LongSparseArray<>();
                mDelegateDrawableCaches.put(context, cache);
            }
            cache.put(key, new WeakReference<ConstantState>(cs));
        }
        return true;
    }
    return false;
}