RecyclerView自定义列表拖拽删除

基础使用

1. 定义Activity和item布局

   <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       android:padding="16dp">
   
       <androidx.recyclerview.widget.RecyclerView
           android:id="@+id/rv"
           android:layout_width="match_parent"
           android:layout_height="match_parent" />
   
   </RelativeLayout>
   

   <androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
       xmlns:app="http://schemas.android.com/apk/res-auto"
       xmlns:tools="http://schemas.android.com/tools"
       android:layout_width="270dp"
       android:layout_height="330dp"
       android:clickable="true"
       android:foreground="?android:attr/selectableItemBackground"
       app:cardBackgroundColor="#393F4E"
       app:cardCornerRadius="16dp"
       app:cardPreventCornerOverlap="false">
   
   
       <androidx.appcompat.widget.AppCompatImageView
           android:id="@+id/iv"
           android:layout_width="170dp"
           android:layout_height="200dp"
           android:layout_gravity="center_horizontal"
           android:layout_marginTop="10dp"
           android:src="@mipmap/ic_launcher" />
   
       <TextView
           android:id="@+id/tvName"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:layout_gravity="center_horizontal"
           android:layout_marginTop="210dp"
           android:paddingTop="10dp"
           android:text="名字"
           android:textColor="@color/white" />
   
       <Button
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:layout_gravity="bottom|center_horizontal"
           android:layout_marginBottom="20dp"
           android:background="#F05079"
           android:text="喜欢" />
   
       <TextView
           android:id="@+id/tvPrecent"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:layout_gravity="right|bottom"
           android:layout_margin="3dp"
           android:textColor="@android:color/white"
           tools:text="1/13" />
   
   
   </androidx.cardview.widget.CardView>
   

2. 设置Adapter和ViewHolder

   这里使用一个通用模板，不参照按照日常使用那样就行，可跳过

   封装的Adapter

   public abstract class UniversalAdapter<T> extends RecyclerView.Adapter<ViewHolder> {
       protected Context mContext;
       protected int mLayoutId;
       protected List<T> mDatas;
       protected LayoutInflater mInflater;
       protected ViewGroup mRv;
       private OnItemClickListener mOnItemClickListener;
   
       public UniversalAdapter setOnItemClickListener(OnItemClickListener onItemClickListener) {
           this.mOnItemClickListener = onItemClickListener;
           return this;
       }
   
       public OnItemClickListener getmOnItemClickListener() {
           return this.mOnItemClickListener;
       }
   
       public UniversalAdapter(Context context, List<T> datas, int layoutId) {
           this.mContext = context;
           this.mInflater = LayoutInflater.from(context);
           this.mLayoutId = layoutId;
           this.mDatas = datas;
       }
   
       public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
           ViewHolder viewHolder = ViewHolder.get(this.mContext, (View)null, parent, this.mLayoutId);
           if(null == this.mRv) {
               this.mRv = parent;
           }
   
           return viewHolder;
       }
   
       protected int getPosition(RecyclerView.ViewHolder viewHolder) {
           return viewHolder.getAdapterPosition();
       }
   
       protected boolean isEnabled(int viewType) {
           return true;
       }
   
       /** @deprecated */
       @Deprecated
       protected void setListener(final ViewGroup parent, final ViewHolder viewHolder, int viewType) {
           if(this.isEnabled(viewType)) {
               viewHolder.itemView.setOnClickListener(new OnClickListener() {
                   public void onClick(View v) {
                       if(UniversalAdapter.this.mOnItemClickListener != null) {
                           int position = UniversalAdapter.this.getPosition(viewHolder);
                           UniversalAdapter.this.mOnItemClickListener.onItemClick(parent, v, UniversalAdapter.this.mDatas.get(position), position);
                       }
   
                   }
               });
               viewHolder.itemView.setOnLongClickListener(new OnLongClickListener() {
                   public boolean onLongClick(View v) {
                       if(UniversalAdapter.this.mOnItemClickListener != null) {
                           int position = UniversalAdapter.this.getPosition(viewHolder);
                           return UniversalAdapter.this.mOnItemClickListener.onItemLongClick(parent, v, UniversalAdapter.this.mDatas.get(position), position);
                       } else {
                           return false;
                       }
                   }
               });
           }
       }
   
       public void onBindViewHolder(ViewHolder holder, int position) {
           this.setListener(position, holder);
           this.convert(holder, this.mDatas.get(position));
       }
   
       protected void setListener(final int position, final ViewHolder viewHolder) {
           if(this.isEnabled(this.getItemViewType(position))) {
               viewHolder.itemView.setOnClickListener(new OnClickListener() {
                   public void onClick(View v) {
                       if(UniversalAdapter.this.mOnItemClickListener != null) {
                           UniversalAdapter.this.mOnItemClickListener.onItemClick(UniversalAdapter.this.mRv, v, UniversalAdapter.this.mDatas.get(position), position);
                       }
   
                   }
               });
               viewHolder.itemView.setOnLongClickListener(new OnLongClickListener() {
                   public boolean onLongClick(View v) {
                       if(UniversalAdapter.this.mOnItemClickListener != null) {
                           int position = UniversalAdapter.this.getPosition(viewHolder);
                           return UniversalAdapter.this.mOnItemClickListener.onItemLongClick(UniversalAdapter.this.mRv, v, UniversalAdapter.this.mDatas.get(position), position);
                       } else {
                           return false;
                       }
                   }
               });
           }
       }
   
       // 将 var2的数据 显示在ViewHolder 的对应 View 中
       public abstract void convert(ViewHolder var1, T var2);
   
       public int getItemCount() {
           return this.mDatas != null?this.mDatas.size():0;
       }
   
       public void setDatas(List<T> list) {
           if(this.mDatas != null) {
               if(null != list) {
                   ArrayList temp = new ArrayList();
                   temp.addAll(list);
                   this.mDatas.clear();
                   this.mDatas.addAll(temp);
               } else {
                   this.mDatas.clear();
               }
           } else {
               this.mDatas = list;
           }
   
           this.notifyDataSetChanged();
       }
   
       public void remove(int i) {
           if(null != this.mDatas && this.mDatas.size() > i && i > -1) {
               this.mDatas.remove(i);
               this.notifyDataSetChanged();
           }
   
       }
   
       public void addDatas(List<T> list) {
           if(null != list) {
               ArrayList temp = new ArrayList();
               temp.addAll(list);
               if(this.mDatas != null) {
                   this.mDatas.addAll(temp);
               } else {
                   this.mDatas = temp;
               }
   
               this.notifyDataSetChanged();
           }
   
       }
   
       public List<T> getDatas() {
           return this.mDatas;
       }
   
       public T getItem(int position) {
           return position > -1 && null != this.mDatas && this.mDatas.size() > position?this.mDatas.get(position):null;
       }
   }
   

   Adapter要用到的Listener

   public interface OnItemClickListener<T> {
       void onItemClick(ViewGroup var1, View var2, T var3, int var4);
   
       boolean onItemLongClick(ViewGroup var1, View var2, T var3, int var4);
   }
   

   封装的ViewHolder

   public class ViewHolder extends RecyclerView.ViewHolder {
       private SparseArray<View> mViews = new SparseArray();
       private int mLayoutId;
   
       public ViewHolder(View itemView) {
           super(itemView);
       }
   
       public static ViewHolder get(Context context, View convertView, ViewGroup parent, int layoutId) {
           if (convertView == null) {
               View holder2 = LayoutInflater.from(context).inflate(layoutId, parent, false);
               ViewHolder holder1 = new ViewHolder(holder2);
               holder1.mLayoutId = layoutId;
               return holder1;
           } else {
               ViewHolder holder = (ViewHolder) convertView.getTag();
               return holder;
           }
       }
   
       public int getLayoutId() {
           return this.mLayoutId;
       }
   
       public <T extends View> T getView(int viewId) {
           View view = (View) this.mViews.get(viewId);
           if (view == null) {
               view = this.itemView.findViewById(viewId);
               this.mViews.put(viewId, view);
           }
   
           return (T) view;
       }
   
       public ViewHolder setText(int viewId, CharSequence text) {
           TextView tv = (TextView) this.getView(viewId);
           tv.setText(text);
           return this;
       }
   
       public ViewHolder setSelected(int viewId, boolean selected) {
           View v = this.getView(viewId);
           v.setSelected(selected);
           return this;
       }
   
       public ViewHolder setImageResource(int viewId, int resId) {
           ImageView view = (ImageView) this.getView(viewId);
           view.setImageResource(resId);
           return this;
       }
   
       public ViewHolder setImageBitmap(int viewId, Bitmap bitmap) {
           ImageView view = (ImageView) this.getView(viewId);
           view.setImageBitmap(bitmap);
           return this;
       }
   
       public ViewHolder setImageDrawable(int viewId, Drawable drawable) {
           ImageView view = (ImageView) this.getView(viewId);
           view.setImageDrawable(drawable);
           return this;
       }
   
       public ViewHolder setBackgroundColor(int viewId, int color) {
           View view = this.getView(viewId);
           view.setBackgroundColor(color);
           return this;
       }
   
       public ViewHolder setBackgroundRes(int viewId, int backgroundRes) {
           View view = this.getView(viewId);
           view.setBackgroundResource(backgroundRes);
           return this;
       }
   
       public ViewHolder setTextColor(int viewId, int textColor) {
           TextView view = (TextView) this.getView(viewId);
           view.setTextColor(textColor);
           return this;
       }
   
       public ViewHolder setTextColorRes(int viewId, int textColorRes) {
           TextView view = (TextView) this.getView(viewId);
           view.setTextColor(this.itemView.getContext().getResources().getColor(textColorRes));
           return this;
       }
   
       @SuppressLint({"NewApi"})
       public ViewHolder setAlpha(int viewId, float value) {
           if (VERSION.SDK_INT >= 11) {
               this.getView(viewId).setAlpha(value);
           } else {
               AlphaAnimation alpha = new AlphaAnimation(value, value);
               alpha.setDuration(0L);
               alpha.setFillAfter(true);
               this.getView(viewId).startAnimation(alpha);
           }
   
           return this;
       }
   
       public ViewHolder setVisible(int viewId, boolean visible) {
           View view = this.getView(viewId);
           view.setVisibility(visible ? View.VISIBLE : View.GONE);
           return this;
       }
   
       public ViewHolder linkify(int viewId) {
           TextView view = (TextView) this.getView(viewId);
           Linkify.addLinks(view, Linkify.ALL);
           return this;
       }
   
       public ViewHolder setTypeface(Typeface typeface, int... viewIds) {
           int[] var3 = viewIds;
           int var4 = viewIds.length;
   
           for (int var5 = 0; var5 < var4; ++var5) {
               int viewId = var3[var5];
               TextView view = (TextView) this.getView(viewId);
               view.setTypeface(typeface);
               view.setPaintFlags(view.getPaintFlags() | 128);
           }
   
           return this;
       }
   
       public ViewHolder setProgress(int viewId, int progress) {
           ProgressBar view = (ProgressBar) this.getView(viewId);
           view.setProgress(progress);
           return this;
       }
   
       public ViewHolder setProgress(int viewId, int progress, int max) {
           ProgressBar view = (ProgressBar) this.getView(viewId);
           view.setMax(max);
           view.setProgress(progress);
           return this;
       }
   
       public ViewHolder setMax(int viewId, int max) {
           ProgressBar view = (ProgressBar) this.getView(viewId);
           view.setMax(max);
           return this;
       }
   
       public ViewHolder setRating(int viewId, float rating) {
           RatingBar view = (RatingBar) this.getView(viewId);
           view.setRating(rating);
           return this;
       }
   
       public ViewHolder setRating(int viewId, float rating, int max) {
           RatingBar view = (RatingBar) this.getView(viewId);
           view.setMax(max);
           view.setRating(rating);
           return this;
       }
   
       public ViewHolder setTag(int viewId, Object tag) {
           View view = this.getView(viewId);
           view.setTag(tag);
           return this;
       }
   
       public ViewHolder setTag(int viewId, int key, Object tag) {
           View view = this.getView(viewId);
           view.setTag(key, tag);
           return this;
       }
   
       public ViewHolder setChecked(int viewId, boolean checked) {
           Checkable view = (Checkable) this.getView(viewId);
           view.setChecked(checked);
           return this;
       }
   
       public ViewHolder setOnClickListener(int viewId, OnClickListener listener) {
           View view = this.getView(viewId);
           view.setOnClickListener(listener);
           return this;
       }
   
       public ViewHolder setOnTouchListener(int viewId, OnTouchListener listener) {
           View view = this.getView(viewId);
           view.setOnTouchListener(listener);
           return this;
       }
   
       public ViewHolder setOnLongClickListener(int viewId, OnLongClickListener listener) {
           View view = this.getView(viewId);
           view.setOnLongClickListener(listener);
           return this;
       }
   
       public void setItemVisible(boolean visible) {
           if (null != this.itemView) {
               if (visible) {
                   if (null != this.itemView.getLayoutParams()) {
                       this.itemView.getLayoutParams().width = -1;
                       this.itemView.getLayoutParams().height = -2;
                   } else {
                       this.itemView.setLayoutParams(new LayoutParams(-1, -2));
                   }
   
                   this.itemView.setVisibility(View.VISIBLE);
               } else {
                   if (null != this.itemView.getLayoutParams()) {
                       this.itemView.getLayoutParams().width = -1;
                       this.itemView.getLayoutParams().height = 1;
                   } else {
                       this.itemView.setLayoutParams(new LayoutParams(-1, 1));
                   }
   
                   this.itemView.setVisibility(View.GONE);
               }
           }
   
       }
   
       public void setHItemVisible(boolean visible) {
           if (null != this.itemView) {
               if (visible) {
                   if (null != this.itemView.getLayoutParams()) {
                       this.itemView.getLayoutParams().width = -2;
                       this.itemView.getLayoutParams().height = -2;
                   } else {
                       this.itemView.setLayoutParams(new LayoutParams(-1, -2));
                   }
   
                   this.itemView.setVisibility(View.VISIBLE);
               } else {
                   if (null != this.itemView.getLayoutParams()) {
                       this.itemView.getLayoutParams().width = -1;
                       this.itemView.getLayoutParams().height = 1;
                   } else {
                       this.itemView.setLayoutParams(new LayoutParams(-1, 1));
                   }
   
                   this.itemView.setVisibility(View.GONE);
               }
           }
   
       }
   }
   

3. 创建

           adapter = object : UniversalAdapter<SwipeCardBean>(this, mDatas, R.layout.item_swipe_card) {
               override fun convert(holder: ViewHolder?, bean: SwipeCardBean?) {
                   holder?.run {
                       setText(R.id.tvName, bean!!.name)
                       setText(R.id.tvPrecent, "${bean.position}/${mDatas.size}")
                       Glide.with(this@MainActivity)
                           .load(bean.url)
                           .into(getView(R.id.iv) as ImageView)
                   }
               }
           }
   
           rv.adapter = adapter
   

自定义LayouManager

1. 重写generateDefaultLayoutParams方法

   为itemView创建layout parameters

       override fun generateDefaultLayoutParams(): RecyclerView.LayoutParams {
           return RecyclerView.LayoutParams(
               ViewGroup.LayoutParams.WRAP_CONTENT,
               ViewGroup.LayoutParams.WRAP_CONTENT
           )
       }
   

2. 重写onLayoutChildren方法

   用来布局itemView

     override fun onLayoutChildren(recycler: RecyclerView.Recycler?, state: RecyclerView.State?) {
           // 回收复用
           detachAndScrapAttachedViews(recycler!!)
   
           // 8个
           // 0 1 2 3 4 5 6 7
           val bottomPosition = if (itemCount < CardConfig.MAX_SHOW_COUNT) {
               0
           } else {
               itemCount - CardConfig.MAX_SHOW_COUNT
           }
   
           for (i in bottomPosition until itemCount) {
               // 复用
               val view = recycler.getViewForPosition(i)
               addView(view)
   
               measureChildWithMargins(view, 0, 0)
   
               // 求padding大小
               val widthSpace = width - getDecoratedMeasuredWidth(view)
               val heightSpace = height - getDecoratedMeasuredHeight(view)
   
               //布局
               layoutDecoratedWithMargins(
                   view,
                   widthSpace / 2,
                   heightSpace / 2,
                   widthSpace / 2 + getDecoratedMeasuredWidth(view),
                   heightSpace / 2 + getDecoratedMeasuredHeight(view)
               )
   
               val level = itemCount - i - 1
   
               if (level > 0) {
                   if (level < CardConfig.MAX_SHOW_COUNT - 1) {
                       view.translationY = (CardConfig.TRANS_Y_GAP * level).toFloat()
                       view.scaleX = 1 - CardConfig.SCALE_GAP * level
                       view.scaleY = 1 - CardConfig.SCALE_GAP * level
                   } else {
                       // 把第四个弄得跟第三个一样
                       view.translationY = (CardConfig.TRANS_Y_GAP * (level - 1)).toFloat()
                       view.scaleX = 1 - CardConfig.SCALE_GAP * (level - 1)
                       view.scaleY = 1 - CardConfig.SCALE_GAP * (level - 1)
                   }
               }
           }
   
   
       }
   

3. 使用

   rv.layoutManager = SwipeCardLayoutManager()
   

自定义ItemTouchHelper的Callback

1. 重写onMove

   Called when ItemTouchHelper wants to move the dragged item from its old position to the new position. 这里不处理，直接返回false

       override fun onMove(
           recyclerView: RecyclerView,
           viewHolder: RecyclerView.ViewHolder,
           target: RecyclerView.ViewHolder
       ): Boolean {
           return false
       }
   

2. 重写onSwipe

   Called when a ViewHolder is swiped by the user. 滑出去删除时调用

       override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {
           val remove = mDatas.removeAt(viewHolder.layoutPosition)
           mDatas.add(0, remove)
           adapter.notifyDataSetChanged()
       }
   

3. 重写onChildDraw

   定义怎么布局子view

    override fun onChildDraw(
           c: Canvas,
           recyclerView: RecyclerView,
           viewHolder: RecyclerView.ViewHolder,
           dX: Float,
           dY: Float,
           actionState: Int,
           isCurrentlyActive: Boolean
       ) {
           super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive)
           Log.i("jintag", "onChildDraw: actionState: $actionState")
   
           val maxDistance = recyclerView.width * 0.5f
           val distance = sqrt(dX * dX + dY * dY)
           var fraction = distance / maxDistance.toDouble()
   
           if (fraction > 1) {
               fraction = 1.0
           }
   
           val itemCount = recyclerView.childCount
   
           for (i in 0 until itemCount) {
               val view = recyclerView.getChildAt(i)
               val level = itemCount - i - 1
   
               if (level > 0) {
                   view.translationY =
                       (CardConfig.TRANS_Y_GAP * level - fraction * CardConfig.TRANS_Y_GAP).toFloat()
                   view.scaleX =
                       (1 - CardConfig.SCALE_GAP * level + fraction * CardConfig.SCALE_GAP).toFloat()
                   view.scaleY =
                       (1 - CardConfig.SCALE_GAP * level + fraction * CardConfig.SCALE_GAP).toFloat()
               }
           }
       }
   

4. 使用

           // 拖拽删除
           val callback = SwipeCardCallback(rv, adapter, mDatas)
           val helper = ItemTouchHelper(callback)
           helper.attachToRecyclerView(rv)