RecyclerView使用onBindViewHolder时，同一个Item总是有两个viewholder对象

RecyclerView中有两个Api来绑定数据：onBindViewHolder( RecyclerView.ViewHolder holder, int position)和带参数onBindViewHolder(RecyclerView.ViewHolder holder, int position, List payloads)局部绑定/刷新数据。

场景：RecyclerView使用viewHolder保存数据时，同一个Item总是有两个viewHolder对象。比如保存上一次的下载时间，百分比等
比如需要在viewHolder中保存上次刷新的数据时，同一个item有两个viewHolder对象，肯定时不行的，这时只需要在mRecycler中设置setSupportsChangeAnimations()为false即可。

原因： RecyclerView默认情况下会创建ViewHolder的另一个副本，以便将视图相互淡化。

另外，当时用带参数的 onBindViewHolder时，因为旧的ViewHolder获取payloads，但新的ViewHolder没有获取到payloads，也需要配置如下代码。

((SimpleItemAnimator)mRecycler.getItemAnimator()).setSupportsChangeAnimations(false);

RecyclerView源码：ItemAnimator 决定使用同一个ViewHolder 还是重新创建ViewHolder，canReuseUpdatedViewHolder()默认返回为true。若为true，则使用同一个ViewHolder。
SimpleItemAnimator继承RecyclerView，通过setSupportsChangeAnimations(),给全局变量mSupportsChangeAnimations （默认为true）设置为false；那么canReuseUpdatedViewHolder()返回为true。
DefaultItemAnimator继承SimpleItemAnimator：canReuseUpdatedViewHolder()中调用super.canReuseUpdatedViewHolder(viewHolder, payloads);即SimpleItemAnimator中的canReuseUpdatedViewHolder()。

RecyclerView源码：

/**
         * When an item is changed, ItemAnimator can decide whether it wants to re-use
         * the same ViewHolder for animations or RecyclerView should create a copy of the
         * item and ItemAnimator will use both to run the animation (e.g. cross-fade).
         * 

         * Note that this method will only be called if the {@link ViewHolder} still has the same
         * type ({@link Adapter#getItemViewType(int)}). Otherwise, ItemAnimator will always receive
         * both {@link ViewHolder}s in the
         * {@link #animateChange(ViewHolder, ViewHolder, ItemHolderInfo, ItemHolderInfo)} method.
         *
         * @param viewHolder The ViewHolder which represents the changed item's old content.
         * @param payloads A non-null list of merged payloads that were sent with change
         *                 notifications. Can be empty if the adapter is invalidated via
         *                 {@link RecyclerView.Adapter#notifyDataSetChanged()}. The same list of
         *                 payloads will be passed into
         *                 {@link RecyclerView.Adapter#onBindViewHolder(ViewHolder, int, List)}
         *                 method if this method returns true.
         *
         * @return True if RecyclerView should just rebind to the same ViewHolder or false if
         *         RecyclerView should create a new ViewHolder and pass this ViewHolder to the
         *         ItemAnimator to animate. Default implementation calls
         *         {@link #canReuseUpdatedViewHolder(ViewHolder)}.
         *
         * @see #canReuseUpdatedViewHolder(ViewHolder)
         */
        public boolean canReuseUpdatedViewHolder(@NonNull ViewHolder viewHolder,
                @NonNull List