Android之RecycleView实现指定范围的拖动效果

1 问题

在RecycleView里面实现指定位置的拖动效果，（这里是实现线性布局的，不是网格布局的）

    @Override    public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {        Log.i(TAG, "onMove viewHolder.getAdapterPosition() is:" + viewHolder.getAdapterPosition());        int itemViewType = viewHolder.getAdapterPosition();        Log.i(TAG, "onMove---------------------------------itemViewType is:" + itemViewType);//        if (itemViewType == 0 || itemViewType == 1 || itemViewType == 16) {//            Log.i(TAG, "onMove---------------------------------itemViewType is:" + itemViewType);//            return false;//        }        int fromPosition = viewHolder.getAdapterPosition();//得到拖动ViewHolder的position        int toPosition = target.getAdapterPosition();//得到目标ViewHolder的position        Log.i(TAG, "onMove---------------------------------fromPosition is:" + fromPosition);        Log.i(TAG, "onMove---------------------------------toPosition is:" + toPosition);//这里的position如果不是指定范围内的话，直接返回false，就拖动不到其它位置了        if (DragUtil.INSTANCE.getProhibitDragIndexs().contains(toPosition)) {            return false;        }        itemTouchAdapter.onMove(fromPosition,toPosition);        return true;    }

2 关键代码如下

MyItemTouchCallback.java

import android.graphics.Canvas;import android.graphics.Color;import android.graphics.drawable.Drawable;import android.util.Log;import androidx.recyclerview.widget.GridLayoutManager;import androidx.recyclerview.widget.ItemTouchHelper;import androidx.recyclerview.widget.RecyclerView;import com.appsinnova.android.keepdrop.manager.FileScanManager;/** * Created by Administrator on 2016/4/12. */public class MyItemTouchCallback extends ItemTouchHelper.Callback {    public static final String TAG = MyItemTouchCallback.class.getSimpleName();    private ItemTouchAdapter itemTouchAdapter;    public MyItemTouchCallback(ItemTouchAdapter itemTouchAdapter){        this.itemTouchAdapter = itemTouchAdapter;    }    @Override    public boolean isLongPressDragEnabled() {        return false;    }    @Override    public boolean isItemViewSwipeEnabled() {        return true;    }    @Override    public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {        Log.i(TAG, "getMovementFlags viewHolder.getAdapterPosition() is:" + viewHolder.getAdapterPosition());        int itemViewType = viewHolder.getAdapterPosition();        Log.i(TAG, "---------------------------------itemViewType is:" + itemViewType);//        if (itemViewType == 0 || itemViewType == 1 || itemViewType == 16) {//            Log.i(TAG, "-getMovementFlags--------------------------------itemViewType is:" + itemViewType);//            return makeMovementFlags(0, 0);//        }        if (recyclerView.getLayoutManager() instanceof GridLayoutManager) {            final int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN | ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;            final int swipeFlags = 0;            return makeMovementFlags(dragFlags, swipeFlags);        } else {            final int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;            //final int swipeFlags = ItemTouchHelper.START | ItemTouchHelper.END;            final int swipeFlags = 0;            Log.i(TAG, "makeMovementFlags start");            return makeMovementFlags(dragFlags, swipeFlags);        }    }    @Override    public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {        Log.i(TAG, "onMove viewHolder.getAdapterPosition() is:" + viewHolder.getAdapterPosition());        int itemViewType = viewHolder.getAdapterPosition();        Log.i(TAG, "onMove---------------------------------itemViewType is:" + itemViewType);//        if (itemViewType == 0 || itemViewType == 1 || itemViewType == 16) {//            Log.i(TAG, "onMove---------------------------------itemViewType is:" + itemViewType);//            return false;//        }        int fromPosition = viewHolder.getAdapterPosition();//得到拖动ViewHolder的position        int toPosition = target.getAdapterPosition();//得到目标ViewHolder的position        Log.i(TAG, "onMove---------------------------------fromPosition is:" + fromPosition);        Log.i(TAG, "onMove---------------------------------toPosition is:" + toPosition);//这里的position如果不是指定范围内的话，直接返回false，就拖动不到其它位置了        if (DragUtil.INSTANCE.getProhibitDragIndexs().contains(toPosition)) {            return false;        }        itemTouchAdapter.onMove(fromPosition,toPosition);        return true;    }    @Override    public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {        int position = viewHolder.getAdapterPosition();        itemTouchAdapter.onSwiped(position);    }    @Override    public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {        if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) {            //滑动时改变Item的透明度            final float alpha = 1 - Math.abs(dX) / (float) viewHolder.itemView.getWidth();            viewHolder.itemView.setAlpha(alpha);            viewHolder.itemView.setTranslationX(dX);        } else {            super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);        }    }    @Override    public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {        if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) {            if (background == null && bkcolor == -1) {                Drawable drawable = viewHolder.itemView.getBackground();                if (drawable == null) {                    bkcolor = 0;                } else {                    background = drawable;                }            }            viewHolder.itemView.setBackgroundColor(Color.LTGRAY);        }        super.onSelectedChanged(viewHolder, actionState);    }    @Override    public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {        super.clearView(recyclerView, viewHolder);        viewHolder.itemView.setAlpha(1.0f);        if (background != null) viewHolder.itemView.setBackgroundDrawable(background);        if (bkcolor != -1) viewHolder.itemView.setBackgroundColor(bkcolor);        //viewHolder.itemView.setBackgroundColor(0);        if (onDragListener!=null){            onDragListener.onFinishDrag();        }    }    private Drawable background = null;    private int bkcolor = -1;    private OnDragListener onDragListener;    public MyItemTouchCallback setOnDragListener(OnDragListener onDragListener) {        this.onDragListener = onDragListener;        return this;    }    public interface OnDragListener{        void onFinishDrag();    }    public interface ItemTouchAdapter {        void onMove(int fromPosition, int toPosition);        void onSwiped(int position);    }}

OnRecyclerItemClickListener.java

import android.view.GestureDetector;import android.view.MotionEvent;import android.view.View;import androidx.core.view.GestureDetectorCompat;import androidx.recyclerview.widget.RecyclerView;/** * Created by Administrator on 2016/4/14. */public class OnRecyclerItemClickListener implements RecyclerView.OnItemTouchListener {    private GestureDetectorCompat mGestureDetector;    private RecyclerView recyclerView;    public OnRecyclerItemClickListener(RecyclerView recyclerView){        this.recyclerView = recyclerView;        mGestureDetector = new GestureDetectorCompat(recyclerView.getContext(),new ItemTouchHelperGestureListener());    }    @Override    public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {        mGestureDetector.onTouchEvent(e);        return false;    }    @Override    public void onTouchEvent(RecyclerView rv, MotionEvent e) {        mGestureDetector.onTouchEvent(e);    }    @Override    public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {    }    private class ItemTouchHelperGestureListener extends GestureDetector.SimpleOnGestureListener {        @Override        public boolean onSingleTapUp(MotionEvent e) {            View child = recyclerView.findChildViewUnder(e.getX(), e.getY());            if (child!=null) {                RecyclerView.ViewHolder vh = recyclerView.getChildViewHolder(child);                onItemClick(vh);            }            return true;        }        @Override        public void onLongPress(MotionEvent e) {            View child = recyclerView.findChildViewUnder(e.getX(), e.getY());            if (child!=null) {                RecyclerView.ViewHolder vh = recyclerView.getChildViewHolder(child);                onLongClick(vh);            }        }    }    public void onLongClick(RecyclerView.ViewHolder vh){}    public void onItemClick(RecyclerView.ViewHolder vh){}}

适配器里面实现接口

MyItemTouchCallback.ItemTouchAdapter

import android.text.TextUtils;import android.util.Log;import android.view.View;import android.widget.ImageView;import org.greenrobot.eventbus.EventBus;import java.util.ArrayList;import java.util.Collections;import java.util.List;import static com.appsinnova.android.keepdrop.recommend.entity.ChannelHead.channelType;public class ChannelManagerAdapter extends BaseMultiItemQuickAdapter implements MyItemTouchCallback.ItemTouchAdapter {    public static final String TAG = ChannelManagerAdapter.class.getSimpleName();    public static final int MY_VEDIO_TYPE = 0;    public static final int MORE_VEDIO_TYPE = 1;    public static final int CAN_EDITABLE = 1;    public static final int CAN_NOT_EDITABLE = 0;    public List results = null;    public ChannelManagerAdapter(List data) {        super(data);        addItemType(ChannelHead.channelHeadType, R.layout.item_channel_head);        addItemType(channelType, R.layout.item_channel);        this.results = data;    }    @Override    protected void convert(BaseViewHolder helper, MultiItemEntity item) {        switch (helper.getItemViewType()) {        }    }    @Override    public void onMove(int fromPosition, int toPosition) {        if (fromPosition==results.size()-1 || toPosition==results.size()-1){            return;        }        if (fromPosition < toPosition) {            for (int i = fromPosition; i < toPosition; i++) {                Collections.swap(results, i, i + 1);            }        } else {            for (int i = fromPosition; i > toPosition; i--) {                Collections.swap(results, i, i - 1);            }        }//这个数据是移动后的数据，会更新原始数据        int size = results.size();        List items = new ArrayList();        RecommendVedioModel recommendVedioModel = SPHelper.getInstance().getObject(SpConstants.RECOMMEND_VEDIO_CATETGORY, RecommendVedioModel.class);        for (int i = 0; i < size; ++i) {            if (results.get(i).getItemType() == channelType) {                RecommendVedioModel.RecommendVedioItem item = (RecommendVedioModel.RecommendVedioItem)results.get(i);                items.add(item);            }        }        if (recommendVedioModel != null) {            recommendVedioModel.items = items;        } else {            Log.i(TAG, "recommendVedioModel is null");        }        SPHelper.getInstance().putObject(SpConstants.RECOMMEND_VEDIO_CATETGORY, recommendVedioModel);        notifyItemMoved(fromPosition, toPosition);    }    @Override    public void onSwiped(int position) {    }}

然后在页面显示的地方

        channelManagerAdapter = ChannelManagerAdapter(allDatas)        val layoutManager = LinearLayoutManager(this)        layoutManager.orientation = LinearLayoutManager.VERTICAL        channelRecycleview.setLayoutManager(layoutManager)        channelRecycleview.setAdapter(channelManagerAdapter)        val itemTouchHelper = ItemTouchHelper(MyItemTouchCallback(channelManagerAdapter))        itemTouchHelper.attachToRecyclerView(channelRecycleview)        channelRecycleview.addOnItemTouchListener(object : OnRecyclerItemClickListener(channelRecycleview) {            override fun onLongClick(vh: RecyclerView.ViewHolder) {                LogUtil.i(TAG, "onLongClick vh.layoutPosition is：" + vh.layoutPosition)                var index = vh.layoutPosition                if (!prohibitDragIndexs.contains(index)) {                    itemTouchHelper.startDrag(vh)                }            }        })

1 问题

2 关键代码如下

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