Android中的拖拽_android recycleview 跨控件拖拽

作者：小小林熬夜学编程 | 2024-03-22 09:08:38

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android recycleview 跨控件拖拽

转载请注明链接：https://blog.csdn.net/feather_wch/article/details/79736307

Android中的拖拽

版本:2018/3/29-1(15:31)-3/30(11:05)

Android中的拖拽

这样一个效果该如何实现？
“我想要拖拽一个控件到另一个布局中，手一松就添加到了该布局中”。

主要的方法有通过View的滑动(如改变控件的布局参数等方法)，滑动到目标区域即可。可以参考教程：https://blog.csdn.net/feather_wch/article/details/78679327

本文的方法是通过给控件设置OnDragListener(拖拽监听器)直接完成该效果，更为简单。

简单实例：将一个控件拖拽到一个布局中

主要思路：
1. 给被拖拽控件添加点击事件监听器，并在内部转交给View.startDrag方法去实现拖拽。
2. 给接收方添加OnDrageListener，会监听到发生在自身区域内的拖拽事件，在拖拽完成的回调中将被拖拽控件添加进来

被拖拽控件：

        mAddButton.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View view, MotionEvent event) {
                if(event.getAction() == MotionEvent.ACTION_DOWN){
                    //1. 剪切板可以保存数据
                    ClipData data = ClipData.newPlainText("", "");
                    //2. 影子
                    View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
                    //3. 震动反馈，不需要震动权限
                    view.performHapticFeedback(HapticFeedbackConstants.LONG_PRESS, HapticFeedbackConstants.FLAG_IGNORE_GLOBAL_SETTING);
                    //4. 拖拽
                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                        view.startDragAndDrop(data, shadowBuilder, view, 0);
                    }else{
                        view.startDrag(data, shadowBuilder, view, 0);
                    }
                    return true;
                }else{
                    return false;
                }
            }
        });
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目标布局接收拖拽的控件：

        mRelativeLayout.setOnDragListener(new View.OnDragListener() {
            @Override
            public boolean onDrag(View v, DragEvent event) {
                switch (event.getAction()){
                    case DragEvent.ACTION_DROP:
                        //1. 响应拖拽，将控件安置到该位置
                        View otherView = (View) event.getLocalState();
                        ViewGroup owner = (ViewGroup) otherView.getParent();
                        owner.removeView(otherView);
                        RelativeLayout relativeLayout = (RelativeLayout) v;
                        relativeLayout.addView(otherView);
                        otherView.setVisibility(View.VISIBLE);
                        break;
                }
                return true;
            }
        });
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实例：从RecyclerViewA中将Item拖拽到另一个RecyclerViewB中

主要思路也就是和上面的一样。
区别在于：接收方和被拖拽方都是RecyclerView，需要通过特定的方法去完成拖拽和添加Item的功能。

1、RVA中需要实现onDrag拖拽和onItemLongclick长按开始拖拽的两种监听器

public interface RecyclerViewOnItemLongClickListenr{
    public boolean onLongClick(View view, ItemDataBean data);
}
public class RecyclerViewOnTouchAndDragListener implements View.OnDragListener, RecyclerViewOnItemLongClickListenr {
    int fromPosition = -1;
    int toPosition = 0;
    RecyclerView mRecyclerView;
    RVAdapter mAdapter;

    public int getFromPosition() {
        return fromPosition;
    }

    public void setFromPosition(int fromPosition) {
        this.fromPosition = fromPosition;
    }

    public int getToPosition() {
        return toPosition;
    }

    public RecyclerViewOnTouchAndDragListener(){
    }
    public RecyclerViewOnTouchAndDragListener(RecyclerView recyclerView, RVAdapter adapter) {
        mRecyclerView = recyclerView;
        mAdapter = adapter;
    }
    @Override
    public boolean onDrag(View v, DragEvent event) {
        if (mRecyclerView == null || mAdapter == null) {
            return false;
        }
        final int action = event.getAction();
        switch (action) {
            /**=======================================================
             * 1. 开始拖拽需要确定当前点击的ItemView
             * 2. 如果点击在界外，则fromPosition= -1, 需要在其他阶段确定点击的Item
             *=========================================================*/
            case DragEvent.ACTION_DRAG_STARTED:
                View itemView = mRecyclerView.findChildViewUnder(event.getX(), event.getY());
                if (itemView != null) {
                    RecyclerView.ViewHolder startViewHolder = mRecyclerView.getChildViewHolder(itemView);
                    fromPosition = startViewHolder.getAdapterPosition();
                    //点击的ItemView不可见, 如同已经被拖走
                    startViewHolder.itemView.setVisibility(View.INVISIBLE);
                }
                return true;
            /**=======================================================
             * 2. 拖拽进入了当前控件的区域, 如果第一阶段没有确定ItemView，该阶段补充确定
             *=========================================================*/
            case DragEvent.ACTION_DRAG_ENTERED:
                if (fromPosition == -1) {
                    itemView = mRecyclerView.findChildViewUnder(event.getX(), event.getY());
                    if (itemView != null) {
                        RecyclerView.ViewHolder startViewHolder = mRecyclerView.getChildViewHolder(itemView);
                        fromPosition = startViewHolder.getAdapterPosition();
                        //点击的ItemView不可见
                        startViewHolder.itemView.setVisibility(View.INVISIBLE);
                    }
                }
                return true;
            /**=======================================================
             * 3. 拖拽过程中对RecyclerView里面的ItemView顺序进行切换
             *=========================================================*/
            case DragEvent.ACTION_DRAG_LOCATION:
                //1. 获取目标View的VeiwHolder
                itemView = mRecyclerView.findChildViewUnder(event.getX(), event.getY());
                if (itemView != null) {
                    RecyclerView.ViewHolder toViewHolder = mRecyclerView.getChildViewHolder(itemView);
                    //2. 获得目标View的Position
                    toPosition = toViewHolder.getAdapterPosition();
                    //3. 可能开始拖拽的位置不在RecylcerView中
                    if (fromPosition == -1) {
                        fromPosition = toPosition;
                    }
                    //4. from 和 to 之间进行位置变换
                    if (fromPosition < toPosition) {
                        for (int i = fromPosition; i < toPosition; i++) {
                            Collections.swap(mAdapter.getCitys(), i, i + 1);
                        }
                    } else {
                        for (int i = fromPosition; i > toPosition; i--) {
                            Collections.swap(mAdapter.getCitys(), i, i - 1);
                        }
                    }
                    mAdapter.notifyItemMoved(fromPosition, toPosition);
                    //5. 已经完成了位置交换
                    fromPosition = toPosition;
                }
                return true;
            case DragEvent.ACTION_DRAG_EXITED:
                v.invalidate();
                return true;
            /**=======================================================
             * 4. 拖拽行为停止，将之前不可见的子Item的View重新可见
             *=========================================================*/
            case DragEvent.ACTION_DROP:
                mRecyclerView.findViewHolderForAdapterPosition(fromPosition).itemView.setVisibility(View.VISIBLE);
                return true;
            case DragEvent.ACTION_DRAG_ENDED:
                return true;
            default:
                break;
        }
        return false;
    }

    /**=======================================================
     * 长按进入拖拽状态，并将控件的数据保存到“剪切板”中
     *=========================================================*/
    @Override
    public boolean onLongClick(View view, ItemDataBean data) {
        //1. 将数据序列化-通过剪切板传输
        Bundle bundle = new Bundle();
        bundle.putParcelable("data", data);
        Intent intent = new Intent();
        intent.putExtra("bundle", bundle);
        ClipData clipData = ClipData.newIntent("intent", intent);
        //2. 影子
        View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
        //3. 震动反馈，不需要震动权限
        view.performHapticFeedback(HapticFeedbackConstants.LONG_PRESS, HapticFeedbackConstants.FLAG_IGNORE_GLOBAL_SETTING);
        //4. 拖拽
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            view.startDragAndDrop(clipData, shadowBuilder, view, 0);
        } else {
            view.startDrag(clipData, shadowBuilder, view, 0);
        }
        return true;
    }
}
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2、RecyclerView的Adapter，将ItemView的长按监听的具体实现转移到我们的点击接口中(只有核心代码)

private RecyclerViewOnItemLongClickListenr mOnItemLongClickListenr;
public void setOnItemLongClickListener(RecyclerViewOnItemLongClickListenr onItemLongClickListener) {
    mOnItemLongClickListenr = onItemLongClickListener;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
    final ViewHolder viewHolder = (ViewHolder) holder;
    viewHolder.mTextView.setText(citys.get(position));
    /**
     * 借助OnLongClickListenr将点击事件转移到自定义的Item长按事件接口
     **/
    if(mOnItemLongClickListenr != null){
        viewHolder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View v) {
                ItemDataBean itemData = new ItemDataBean();
                itemData.text =  viewHolder.mTextView.getText().toString();
                return mOnItemLongClickListenr.onLongClick(v, itemData);
            }
        });
    }
}
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3、需要通过序列化传给目标RV的数据实体类

public class ItemDataBean implements Parcelable {
    public String text;

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(this.text);
    }

    public ItemDataBean() {
    }

    protected ItemDataBean(Parcel in) {
        this.text = in.readString();
    }

    public static final Parcelable.Creator<ItemDataBean> CREATOR = new Parcelable.Creator<ItemDataBean>() {
        @Override
        public ItemDataBean createFromParcel(Parcel source) {
            return new ItemDataBean(source);
        }

        @Override
        public ItemDataBean[] newArray(int size) {
            return new ItemDataBean[size];
        }
    };
}
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4、目标RVB接收拖拽控件的代码

mRecyclerView2.setOnDragListener(new View.OnDragListener() {
    @Override
    public boolean onDrag(View v, DragEvent event) {
        switch (event.getAction()) {
            /**============================
             *  接收其他的控件放置到该RV内部
             *============================*/
            case DragEvent.ACTION_DROP:
                //1. 层层获取到传递来的数据(通过Parcelable序列化)
                ClipData clipData = event.getClipData();
                ClipData.Item clipDataItem= clipData.getItemAt(0);
                Intent intent = clipDataItem.getIntent();
                Bundle bundle = intent.getBundleExtra("bundle");
                bundle.setClassLoader(getClass().getClassLoader());
                ItemDataBean itemData = bundle.getParcelable("data");

                //2. 获取到想要加入的位置
                View childView = mRecyclerView2.findChildViewUnder(event.getX(), event.getY());
                if(childView != null){
                    RecyclerView.ViewHolder toViewHolder = mRecyclerView2.getChildViewHolder(childView);
                    int targetPosition = toViewHolder.getAdapterPosition();

                    //3. 将控件添加到本控件内部
                    mRVAdapter2.getCitys().add(targetPosition, itemData.text);
                    mRVAdapter2.notifyItemInserted(targetPosition);
                    mRecyclerView2.scrollToPosition(targetPosition);

                    //4. 让第一个RV删除掉移动过来的Item
                    int fromPosition = mViewOnTouchAndDragListener.getFromPosition();
                    if(fromPosition != -1){
                        mRVAdapter.getCitys().remove(fromPosition);
                        mRVAdapter.notifyItemRemoved(fromPosition);
                        mViewOnTouchAndDragListener.setFromPosition(-1); //归零防止出问题
                    }
                }
                break;
            default:
                break;
        }
        return true;
    }
});
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5、给RVA设置两种监听器

//1. 相应拖拽：自动排序效果
mRecyclerView.setOnDragListener(mViewOnTouchAndDragListener = new RecyclerViewOnTouchAndDragListener(mRecyclerView, mRVAdapter));
//2. 长按开启拖拽
mRVAdapter.setOnItemLongClickListener(new RecyclerViewOnTouchAndDragListener());1
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参考和学习资料

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