Android RecyclerView 图片拖拽排序

效果图如下：

该应用场景很常见，效果较炫酷，实现起来其实很简单。系统提供了实现辅助工具ItemTouchHelper，通过ItemTouchHelper能快速实现拖拽效果。

ItemTouchHelper helper = new ItemTouchHelper();
helper.attachToRecyclerView(recyclerView);

没看错，就是一行代码即可实现你想要的效果！

下面详细介绍 ItemTouchHelper

ItemTouchHelper helper = new ItemTouchHelper(new ItemTouchHelper.Callback() {
        //线性布局和网格布局都可以使用
        @Override
        public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
            int dragFrlg = 0;
            if (recyclerView.getLayoutManager() instanceof GridLayoutManager){
                dragFrlg = ItemTouchHelper.UP|ItemTouchHelper.DOWN|ItemTouchHelper.LEFT|ItemTouchHelper.RIGHT;
            }else if(recyclerView.getLayoutManager() instanceof LinearLayoutManager){
                dragFrlg = ItemTouchHelper.LEFT|ItemTouchHelper.RIGHT;
            }
            return makeMovementFlags(dragFrlg,0);
        }

        @Override
        public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
            //得到当拖拽的viewHolder的Position  每一次Position改变，该方法都回调
            int fromPosition = viewHolder.getAdapterPosition();
            //拿到当前拖拽到的item的viewHolder
            int toPosition = target.getAdapterPosition();
            if (fromPosition < toPosition ) {
                if (toPosition < d.size() - 1) {//此处表明最后一个item不可替换，一般最后一个item是添加更多图片+
                    for (int i = fromPosition; i < toPosition; i++) {
                        Collections.swap(datas, i, i + 1);
                    }
                    ap.notifyItemMoved(fromPosition, toPosition);
                }
            } else {
                for (int i = fromPosition; i > toPosition; i--) {
                    Collections.swap(datas, i, i - 1);
                }
                ap.notifyItemMoved(fromPosition, toPosition);
            }
            return true;
        }

        @Override
        public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
              //侧滑删除可以使用；
        }

        @Override
        public boolean isLongPressDragEnabled() {
            return true;
        }
        /**
         * 长按选中Item的时候开始调用
         * 长按高亮
         * @param viewHolder
         * @param actionState
         */
        @Override
        public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {
            if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) {
                viewHolder.itemView.setBackgroundColor(Color.RED);
                viewHolder.itemView.setScaleX(1.2f);
                viewHolder.itemView.setScaleY(1.2f);
                //获取系统震动服务//震动70毫秒
//                Vibrator vib = (Vibrator) getSystemService(Service.VIBRATOR_SERVICE);
//                vib.vibrate(70);
            }
            super.onSelectedChanged(viewHolder, actionState);
        }

        /**
         * 手指松开的时候还原高亮
         * @param recyclerView
         * @param viewHolder
         */
        @Override
        public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
            super.clearView(recyclerView, viewHolder);
            viewHolder.itemView.setBackgroundColor(Color.parseColor("#21f1f1"));
            viewHolder.itemView.setScaleX(1.0f);
            viewHolder.itemView.setScaleY(1.0f);
            ap.notifyDataSetChanged();  //完成拖动后刷新适配器，这样拖动后删除就不会错乱
        }
    });

文末

DEMO链接