Android使用RecycleView实现拖拽交换item位置

public void attachToRecyclerView(@Nullable RecyclerView recyclerView) {}

//决定拖拽/滑动的方向public abstract int getMovementFlags(RecyclerView recyclerView,        ViewHolder viewHolder);//和位置交换有关,可用于实现drag功能public abstract boolean onMove(RecyclerView recyclerView,        ViewHolder viewHolder, ViewHolder target);//和滑动有关,可用于实现swipe功能public abstract void onSwiped(ViewHolder viewHolder, int direction);//是否长按启用拖拽功能,默认是truepublic boolean isLongPressDragEnabled() {return true;}//是否支持滑动,默认truepublic boolean isItemViewSwipeEnabled() {return true;}//和目标View的状态改变有关,例如drag,swipe,idepublic void onSelectedChanged(ViewHolder viewHolder, int actionState) {}//和移除View的状态有关,通常用于清除在onSelectedChanged,onChildDraw中对View设置的动画public void clearView(RecyclerView recyclerView, ViewHolder viewHolder) {}

/** * 定义RecycleView的Adapter和SimpleItemTouchHelperCallback直接交互的接口方法 * Created by mChenys on 2017/2/16. */public interface ItemTouchHelperAdapter {  //数据交换  void onItemMove(RecyclerView.ViewHolder source, RecyclerView.ViewHolder target);  //数据删除  void onItemDissmiss(RecyclerView.ViewHolder source);  //drag或者swipe选中  void onItemSelect(RecyclerView.ViewHolder source);  //状态清除  void onItemClear(RecyclerView.ViewHolder source);}

/** * 处理RecycleView的选中,拖拽移动,拖拽删除的实现类 * Created by mChenys on 2017/2/16. */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; //允许上下的拖动    //int dragFlags =ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT; //允许左右的拖动    //int swipeFlags = ItemTouchHelper.LEFT; //只允许从右向左侧滑    //int swipeFlags = ItemTouchHelper.DOWN; //只允许从上向下侧滑    //一般使用makeMovementFlags(int,int)或makeFlag(int, int)来构造我们的返回值    //makeMovementFlags(dragFlags, swipeFlags)    int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN | ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT; //允许上下左右的拖动    return makeMovementFlags(dragFlags, 0);  }  @Override  public boolean isLongPressDragEnabled() {    return true;//长按启用拖拽  }  @Override  public boolean isItemViewSwipeEnabled() {    return false; //不启用拖拽删除  }  @Override  public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder source, RecyclerView.ViewHolder target) {    //通过接口传递拖拽交换数据的起始位置和目标位置的ViewHolder    mAdapter.onItemMove(source, target);    return true;  }  @Override  public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {    //移动删除回调,如果不用可以不用理    // mAdapter.onItemDissmiss(viewHolder);  }  @Override  public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {    super.onSelectedChanged(viewHolder, actionState);    if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) {      //当滑动或者拖拽view的时候通过接口返回该ViewHolder      mAdapter.onItemSelect(viewHolder);    }  }  @Override  public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {    super.clearView(recyclerView, viewHolder);    if (!recyclerView.isComputingLayout()) {      //当需要清除之前在onSelectedChanged或者onChildDraw,onChildDrawOver设置的状态或者动画时通过接口返回该ViewHolder      mAdapter.onItemClear(viewHolder);    }  }}

/** * Created by mChenys on 2017/2/15. */public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> implements ItemTouchHelperAdapter {  ...  @Override  public MyAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {   ...  }  @Override  public void onBindViewHolder(final MyAdapter.MyViewHolder holder, int position) {    ...  }  @Override  public int getItemCount() {    //注意:这里最少有一个,因为有多了一个添加按钮    return null == mData ? 1 : mData.size() + 1;  }  @Override  public void onItemMove(RecyclerView.ViewHolder source,   RecyclerView.ViewHolder target) {    int fromPosition = source.getAdapterPosition();    int toPosition = target.getAdapterPosition();    if (fromPosition < mData.size() && toPosition < mData.size()) {      //交换数据位置      Collections.swap(mData, fromPosition, toPosition);      //刷新位置交换      notifyItemMoved(fromPosition, toPosition);    }    //移动过程中移除view的放大效果    onItemClear(source);  }  @Override  public void onItemDissmiss(RecyclerView.ViewHolder source) {    int position = source.getAdapterPosition();    mData.remove(position); //移除数据    notifyItemRemoved(position);//刷新数据移除  }  @Override  public void onItemSelect(RecyclerView.ViewHolder viewHolder) {    //当拖拽选中时放大选中的view    viewHolder.itemView.setScaleX(1.2f);    viewHolder.itemView.setScaleY(1.2f);  }  @Override  public void onItemClear(RecyclerView.ViewHolder viewHolder) {    //拖拽结束后恢复view的状态    viewHolder.itemView.setScaleX(1.0f);    viewHolder.itemView.setScaleY(1.0f);  }  public class MyViewHolder extends RecyclerView.ViewHolder {   ...    public MyViewHolder(View itemView) {      super(itemView);     ...    }  }}

/** * Created by mChenys on 2017/2/16. */public class MainActivity extends AppCompatActivity {  ...  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    ...    mRecyclerView = (RecyclerView) findViewById(R.id.recycleView);    //创建adapter    MyAdapter myAdapter = new MyAdapter(this, mData);    //设置默认的布局方式    mRecyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));    //设置adapter    mRecyclerView.setAdapter(myAdapter);    //创建SimpleItemTouchHelperCallback    ItemTouchHelper.Callback callback = new SimpleItemTouchHelperCallback(myAdapter);    //用Callback构造ItemtouchHelper    ItemTouchHelper touchHelper = new ItemTouchHelper(callback);     //调用ItemTouchHelper的attachToRecyclerView方法建立联系    touchHelper.attachToRecyclerView(mRecyclerView);  }  @Override  public boolean onCreateOptionsMenu(Menu menu) {    ...    return super.onCreateOptionsMenu(menu);  }  @Override  public boolean onOptionsItemSelected(MenuItem item) {    ...    return super.onOptionsItemSelected(item);  }}