RecyclerView進(jìn)階：使用ItemTouchHelper實(shí)現(xiàn)拖拽和側(cè)滑刪除效果

public interface ItemTouchHelperAdapter {
  //數(shù)據(jù)交換
  void onItemMove(int fromPosition,int toPosition);
  //數(shù)據(jù)刪除
  void onItemDissmiss(int position);
}

public class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> implements ItemTouchHelperAdapter {
  //數(shù)據(jù)
  private List<String> mData;
  ...
   @Override
  public void onItemMove(int fromPosition, int toPosition) {
    //交換位置
    Collections.swap(mData,fromPosition,toPosition);
    notifyItemMoved(fromPosition,toPosition);
  }

  @Override
  public void onItemDissmiss(int position) {
    //移除數(shù)據(jù)
    mData.remove(position);
    notifyItemRemoved(position);
  }

}

  @Override
  public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
    int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;    //允許上下的拖動(dòng)
    int swipeFlags = ItemTouchHelper.LEFT;  //只允許從右向左側(cè)滑
    return makeMovementFlags(dragFlags,swipeFlags);
  }

  @Override
  public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
    //onItemMove是接口方法
    mAdapter.onItemMove(viewHolder.getAdapterPosition(),target.getAdapterPosition()); 
    return true;
  }

  @Override
  public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
    //onItemDissmiss是接口方法
    mAdapter.onItemDissmiss(viewHolder.getAdapterPosition());
  }

public class SimpleItemTouchHelperCallback extends ItemTouchHelper.Callback{

  private ItemTouchHelperAdapter mAdapter;

  public SimpleItemTouchHelperCallback(ItemTouchHelperAdapter adapter){
    mAdapter = adapter;
  }

  @Override
  public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
    int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
    int swipeFlags = ItemTouchHelper.LEFT;
    return makeMovementFlags(dragFlags,swipeFlags);
  }

  @Override
  public boolean isLongPressDragEnabled() {
    return true;
  }

  @Override
  public boolean isItemViewSwipeEnabled() {
    return true;
  }

  @Override
  public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
    mAdapter.onItemMove(viewHolder.getAdapterPosition(),target.getAdapterPosition());
    return true;
  }

  @Override
  public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
    mAdapter.onItemDissmiss(viewHolder.getAdapterPosition());
  }
}

  //先實(shí)例化Callback
  ItemTouchHelper.Callback callback = new SimpleItemTouchHelperCallback(myAdapter);
  //用Callback構(gòu)造ItemtouchHelper
  ItemTouchHelper touchHelper = new ItemTouchHelper(callback);
  //調(diào)用ItemTouchHelper的attachToRecyclerView方法建立聯(lián)系
  touchHelper.attachToRecyclerView(mRecyclerView);

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  android:layout_height="wrap_content"
  android:layout_width="match_parent"
  android:orientation="horizontal">

  <android.support.v7.widget.CardView
    android:layout_width="match_parent"
    android:layout_height="80dp"
    android:background="#ffffff"
    android:layout_marginLeft="4dp"
    android:layout_marginRight="4dp"
    android:layout_marginBottom="4dp"
    app:cardCornerRadius="1dp"
    app:elevation="1dp"
    app:contentPadding="1dp">
    <RelativeLayout
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:background="#ffffff">
      <TextView
        android:id="@+id/item"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="22sp"
        android:padding="4dp"
        android:layout_centerInParent="true"/>

    </RelativeLayout>
  </android.support.v7.widget.CardView>

  <FrameLayout
    android:layout_width="100dp"
    android:layout_height="match_parent"
    android:layout_marginRight="4dp"
    android:layout_marginBottom="4dp"
    android:background="#f33213">

    <ImageView
      android:id="@+id/iv_img"
      android:layout_width="50dp"
      android:layout_height="50dp"
      android:layout_gravity="center"
      android:src="@mipmap/ic_eye_72"
      android:visibility="invisible"/>
    <TextView
      android:id="@+id/tv_text"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="左滑刪除"
      android:textSize="18sp"
      android:textColor="#ffffff"
      android:layout_gravity="center"/>
  </FrameLayout>
</LinearLayout>

public class SimpleItemTouchHelperCallback extends ItemTouchHelper.Callback{

  //省略上面的代碼....

  //限制ImageView長度所能增加的最大值
  private double ICON_MAX_SIZE = 50;
  //ImageView的初始長寬
  private int fixedWidth = 150;

  @Override
  public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
    super.clearView(recyclerView, viewHolder);
    //重置改變，防止由于復(fù)用而導(dǎo)致的顯示問題
    viewHolder.itemView.setScrollX(0);
    ((MyAdapter.NormalItem)viewHolder).tv.setText("左滑刪除");
    FrameLayout.LayoutParams params = (FrameLayout.LayoutParams) ((MyAdapter.NormalItem) viewHolder).iv.getLayoutParams();
    params.width = 150;
    params.height = 150;
    ((MyAdapter.NormalItem) viewHolder).iv.setLayoutParams(params);
    ((MyAdapter.NormalItem) viewHolder).iv.setVisibility(View.INVISIBLE);
  }

  @Override
  public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {
    //僅對側(cè)滑狀態(tài)下的效果做出改變
    if (actionState ==ItemTouchHelper.ACTION_STATE_SWIPE){
      //如果dX小于等于刪除方塊的寬度，那么我們把該方塊滑出來
      if (Math.abs(dX) <= getSlideLimitation(viewHolder)){
        viewHolder.itemView.scrollTo(-(int) dX,0);
      }
      //如果dX還未達(dá)到能刪除的距離，此時(shí)慢慢增加“眼睛”的大小，增加的最大值為ICON_MAX_SIZE
      else if (Math.abs(dX) <= recyclerView.getWidth() / 2){
        double distance = (recyclerView.getWidth() / 2 -getSlideLimitation(viewHolder));
        double factor = ICON_MAX_SIZE / distance;
        double diff = (Math.abs(dX) - getSlideLimitation(viewHolder)) * factor;
        if (diff >= ICON_MAX_SIZE)
          diff = ICON_MAX_SIZE;
        ((MyAdapter.NormalItem)viewHolder).tv.setText("");  //把文字去掉
        ((MyAdapter.NormalItem) viewHolder).iv.setVisibility(View.VISIBLE); //顯示眼睛
        FrameLayout.LayoutParams params = (FrameLayout.LayoutParams) ((MyAdapter.NormalItem) viewHolder).iv.getLayoutParams();
        params.width = (int) (fixWidth + diff);
        params.height = (int) (fixWidth + diff);
        ((MyAdapter.NormalItem) viewHolder).iv.setLayoutParams(params);
      }
    }else {
      //拖拽狀態(tài)下不做改變，需要調(diào)用父類的方法
      super.onChildDraw(c,recyclerView,viewHolder,dX,dY,actionState,isCurrentlyActive);
    }
  }

  /**
   * 獲取刪除方塊的寬度
   */
  public int getSlideLimitation(RecyclerView.ViewHolder viewHolder){
    ViewGroup viewGroup = (ViewGroup) viewHolder.itemView;
    return viewGroup.getChildAt(1).getLayoutParams().width;
  }
}