RecyclerView配合ItemTouchHelper实现频道排序、移动

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功能介绍

使用RecyclerView配合ItemTouchHelper实现仿今日头条的频道排序、移动,第一个位置不动,长按拖拽进入编辑模式等功能:

效果如下:

核心代码

    //重写ItemTouchHelperAdapter下的2个方法@Overridepublic void onItemMove(int fromPosition, int toPosition) {Collections.swap(mData, fromPosition, toPosition);notifyItemMoved(fromPosition, toPosition);}@Overridepublic void onItemDismiss(int position) {mData.remove(position);notifyItemRemoved(position);}

这两个方法监听拖拽动作,修改适配器

重点在ItemDragHelperCallback重写getMovementFlags()方法来指定可以支持的拖放和滑动的方向

    public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {int dragFlags = setDragFlags(recyclerView);int swipeFlags = 0;return makeMovementFlags(dragFlags, swipeFlags);}

想要实现移动,则必须在onMove()方法返回为true,返回false则不移动

    @Overridepublic boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {//保持第一个item长按不能移动if (viewHolder.getAdapterPosition() == 0){return false;}//保持第一个item不能移动if (target.getAdapterPosition() == 0){return false;}else {mAdapter.onItemMove(viewHolder.getAdapterPosition(),target.getAdapterPosition());return true;}}

下面附下ItemDragHelperCallback 文件整体代码:

public class ItemDragHelperCallback extends ItemTouchHelper.Callback {private final ItemTouchHelperAdapter mAdapter;public ItemDragHelperCallback(ItemTouchHelperAdapter mAdapter) {this.mAdapter = mAdapter;}//重写getMovementFlags()方法来指定可以支持的拖放和滑动的方向public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {int dragFlags = setDragFlags(recyclerView);int swipeFlags = 0;return makeMovementFlags(dragFlags, swipeFlags);}private int setDragFlags(RecyclerView recyclerView) {int dragFlags;RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();if (layoutManager instanceof GridLayoutManager || layoutManager instanceof StaggeredGridLayoutManager) {dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN | ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;} else {dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;}return dragFlags;}@Overridepublic boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {//保持第一个item长按不能移动if (viewHolder.getAdapterPosition() == 0){return false;}//保持第一个item不能移动if (target.getAdapterPosition() == 0){return false;}else {mAdapter.onItemMove(viewHolder.getAdapterPosition(),target.getAdapterPosition());return true;}}@Overridepublic void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {mAdapter.onItemDismiss(viewHolder.getAdapterPosition());}public boolean isLongPressDragEnabled() {return true;}public boolean isItemViewSwipeEnabled() {return true;}public interface ItemTouchHelperAdapter {void onItemMove(int fromPosition, int toPosition);void onItemDismiss(int position);}//滑动动画public void onChildDraw(Canvas c, RecyclerView recyclerView,RecyclerView.ViewHolder viewHolder, float dX, float dY,int actionState, boolean isCurrentlyActive) {if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) {float width = (float) viewHolder.itemView.getWidth();float alpha = 1.0f - Math.abs(dX) / width;viewHolder.itemView.setAlpha(alpha);viewHolder.itemView.setTranslationX(dX);} else {super.onChildDraw(c, recyclerView, viewHolder, dX, dY,actionState, isCurrentlyActive);}}}

下面附上项目下载地址

http://download.csdn.net/download/shanshan_1117/10201196

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