ItemTouchHelper实现拖拽和侧滑删除

转载: https://github.com/iPaulPro/Android-ItemTouchHelper-Demo/

1. 编写item布局文件:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/item"
    android:layout_width="match_parent"
    android:layout_height="?listPreferredItemHeight"
    android:clickable="true"
    android:focusable="true"
    android:foreground="?selectableItemBackground">

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:layout_marginLeft="16dp"
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <ImageView
        android:id="@+id/handle"
        android:layout_width="?listPreferredItemHeight"
        android:layout_height="match_parent"
        android:layout_gravity="center_vertical|right"
        android:scaleType="center"
        android:src="@drawable/ic_reorder_grey_500_24dp" />
FrameLayout>

2.编写一个触发滑动的监听

/**
 * Listener for manual initiation of a drag.
 */
public interface OnStartDragListener {

    /**
     * Called when a view is requesting a start of a drag.
     *
     * @param viewHolder The holder of the view to drag.
     */
    /*自定义滑动或拖拽事件的开启回调方法*/
    void onStartDrag(RecyclerView.ViewHolder viewHolder);

}

3.编写通知Callback监听器item处于激活状态的监听

/**
 * Interface to notify an item ViewHolder of relevant callbacks from {@link
 * ItemTouchHelper.Callback}.
 */
public interface ItemTouchHelperViewHolder {

    /**
     * Called when the {@link ItemTouchHelper} first registers an item as being moved or swiped.
     * Implementations should update the item view to indicate it's active state.
     */
    /*当item被拖拽或者滑动的时候, item背景变为激活状态*/
    void onItemSelected();


    /**
     * Called when the {@link ItemTouchHelper} has completed the move or swipe, and the active item
     * state should be cleared.
     */
    /*当滑动或拖拽完成后,激活的item的背景应恢复为原来状态*/
    void onItemClear();
}

4. 监听item滑动或者拖拽:

/**
 * Interface to listen for a move or dismissal event from a {@link ItemTouchHelper.Callback}.
 */
public interface ItemTouchHelperAdapter {

    /**
     * Called when an item has been dragged far enough to trigger a move. This is called every time
     * an item is shifted, and not at the end of a "drop" event.

     * 

     * Implementations should call {@link RecyclerView.Adapter#notifyItemMoved(int, int)} after
     * adjusting the underlying data to reflect this move.
     *
     * @param fromPosition The start position of the moved item.
     * @param toPosition   Then resolved position of the moved item.
     * @return True if the item was moved to the new adapter position.
     *
     * @see RecyclerView#getAdapterPositionFor(RecyclerView.ViewHolder)
     * @see RecyclerView.ViewHolder#getAdapterPosition()
     */
    /*item被拖拽时调用*/
    boolean onItemMove(int fromPosition, int toPosition);


    /**
     * Called when an item has been dismissed by a swipe.

     * 

     * Implementations should call {@link RecyclerView.Adapter#notifyItemRemoved(int)} after
     * adjusting the underlying data to reflect this removal.
     *
     * @param position The position of the item dismissed.
     *
     * @see RecyclerView#getAdapterPositionFor(RecyclerView.ViewHolder)
     * @see RecyclerView.ViewHolder#getAdapterPosition()
     */
    /*item滑动删除时调用*/
    void onItemDismiss(int position);
}

5. 编写RecyclerView.Adapter实现类:

/**
 * Simple RecyclerView.Adapter that implements {@link ItemTouchHelperAdapter} to respond to move and
 * dismiss events from a {@link android.support.v7.widget.helper.ItemTouchHelper}.
 */
public class RecyclerListAdapter extends RecyclerView.Adapter<RecyclerListAdapter.ItemViewHolder>
        implements ItemTouchHelperAdapter {

    private final List mItems = new ArrayList<>();

    private final OnStartDragListener mDragStartListener;

    public RecyclerListAdapter(Context context, OnStartDragListener dragStartListener) {
        mDragStartListener = dragStartListener;
        mItems.addAll(Arrays.asList(context.getResources().getStringArray(R.array.dummy_items)));
    }

    @Override
    public ItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_main, parent, false);
        ItemViewHolder itemViewHolder = new ItemViewHolder(view);
        return itemViewHolder;
    }

    @Override
    public void onBindViewHolder(final ItemViewHolder holder, int position) {
        holder.textView.setText(mItems.get(position));

        // Start a drag whenever the handle view it touched
        holder.handleView.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                if (MotionEventCompat.getActionMasked(event) == MotionEvent.ACTION_DOWN) {
                    mDragStartListener.onStartDrag(holder);
                }
                return false;
            }
        });
    }

    @Override
    public void onItemDismiss(int position) {
        mItems.remove(position);
        notifyItemRemoved(position);
    }

    @Override
    public boolean onItemMove(int fromPosition, int toPosition) {
        Collections.swap(mItems, fromPosition, toPosition);
        notifyItemMoved(fromPosition, toPosition);
        return true;
    }

    @Override
    public int getItemCount() {
        return mItems.size();
    }

    /**
     * Simple example of a view holder that implements {@link ItemTouchHelperViewHolder} and has a
     * "handle" view that initiates a drag event when touched.
     */
    public static class ItemViewHolder extends RecyclerView.ViewHolder implements
            ItemTouchHelperViewHolder {

        public final TextView textView;
        public final ImageView handleView;

        public ItemViewHolder(View itemView) {
            super(itemView);
            textView = (TextView) itemView.findViewById(R.id.text);
            handleView = (ImageView) itemView.findViewById(R.id.handle);
        }

        @Override
        public void onItemSelected() {
            itemView.setBackgroundColor(Color.LTGRAY);
        }

        @Override
        public void onItemClear() {
            itemView.setBackgroundColor(0);
        }
    }
}

6. 编写Activity

public class RecylerViewListActivity  extends AppCompatActivity implements OnStartDragListener{
    private RecyclerView mRecyclerView;
    private ItemTouchHelper mItemTouchHelper;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_swipe_recycler);
        mRecyclerView= (RecyclerView) findViewById(R.id.recycler);

        RecyclerListAdapter adapter = new RecyclerListAdapter(this, this);

        mRecyclerView.setHasFixedSize(true);
        mRecyclerView.setAdapter(adapter);
        mRecyclerView.setItemAnimator(new DefaultItemAnimator());
        mRecyclerView.addItemDecoration(new DividerItemDecoration(this,DividerItemDecoration.VERTICAL_LIST));
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));

        ItemTouchHelper.Callback callback = new SimpleItemTouchHelperCallback(adapter);
        mItemTouchHelper = new ItemTouchHelper(callback);
        mItemTouchHelper.attachToRecyclerView(mRecyclerView);

    }

    @Override
    public void onStartDrag(RecyclerView.ViewHolder viewHolder) {

        //开启滑动或者拖拽
        mItemTouchHelper.startDrag(viewHolder);
    }
}