AppCompatDrawableManager.java 文件源码

private Drawable getCachedDelegateDrawable(@NonNull Context context, long key) {
    Drawable drawable = null;
    synchronized (this.mDelegateDrawableCacheLock) {
        LongSparseArray<WeakReference<ConstantState>> cache = (LongSparseArray) this.mDelegateDrawableCaches.get(context);
        if (cache == null) {
        } else {
            WeakReference<ConstantState> wr = (WeakReference) cache.get(key);
            if (wr != null) {
                ConstantState entry = (ConstantState) wr.get();
                if (entry != null) {
                    drawable = entry.newDrawable(context.getResources());
                } else {
                    cache.delete(key);
                }
            }
        }
    }
    return drawable;
}