完全自定义样式的一句话实现RecyclerView的单选多选

一句代码实现RecyclerView的单选多选效果，并且样式完全自定义。哈哈，其实所谓的一句话哔哔哔都是合理封装后的结果 ，根据项目常用需求封装出常用的效果。

今天的主题是封装RecyclerView的单选多选，现在大家应该都是用的RecyclerView开发列表数据吧。

因为实际项目开发中单选和多选的样式多种多样，所以这个扩展性需要下放到调用者。

先看图～

单选样式图：

多选样式图：

多选后的结果图：

这是接着上一篇博客RecyclerView的通用快速适配封装的基础上写的，所以你要和整个ReccylerView 的通用Adapter封装在一起用，因为这个实现的基础是对整个adapter的封装下添加单选多选逻辑的。

1、定义RecyclerView的选中状态（单选、多选、正常）

    public static final int CHOICE_MODE_NONE = 0;
    public static final int CHOICE_MODE_SINGLE = 1;
    public static final int CHOICE_MODE_MULTIPLE = 2;
    public static final int INVALID_POSITION = -1;
    private int mChoiceMode = CHOICE_MODE_NONE;

2、定义选中状态和位置的存储类

这里选择SpareseBooleanArray来存储位置和选择状态之间的关系，这个数据结构可以理解为以int值为键，boolean为值的一个简单的Map。

    private SparseBooleanArray mCheckStates;
    private int mChoiceMode = CHOICE_MODE_NONE;
    private int mCheckedItemCount;
    public void setChoiceMode(int choiceMode) {
        mChoiceMode = choiceMode;
        if (mChoiceMode != CHOICE_MODE_NONE) {
            if (mCheckStates == null) {
                mCheckStates = new SparseBooleanArray(0);
             }
         }
     }

3、单选和多选的状态改变及其在视图上的改变

下面是关键代码，先让集合的数据结构继承Checkable的接口，相当于让item自己存储来自己的选中状态，然后界面根据对于pisition 的数据结构刷新自己的视图，从而实现完全的自定义选中状态的视图变化。

public class Tag implements Checkable{
    /**
     * tid : 2
     * name : 卧槽
     */

    public String tid;
    public String name;
    private boolean mChecked;

    @Override
    public void setChecked(boolean checked) {
        mChecked = checked;
    }

    @Override
    public boolean isChecked() {
        return mChecked;
    }

    @Override
    public void toggle() {
        setChecked(!mChecked);
    }
}

然后先说简单的情况，首先这里要获取该item的点击事件，如果是多选的话，先存储点击这个位置的选中状态。然后根据选中状态更新mCheckedItemCount数量，最后刷新视图。

然后来看单选的情况，如果点击item之前有选中的了，则先消去或者说还原上一个，如果是选中就存储并刷新视图，如果没有选中就跳过。代码和这里有点出入，但是思想都是一样，代码有点乱，你可以自己优化一下。

viewHolder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int position = viewHolder.getAdapterPosition();

                if (mChoiceMode != CHOICE_MODE_NONE && mData.get(position) instanceof Checkable) {
                    if (mChoiceMode == CHOICE_MODE_SINGLE) {
                        boolean checked = !mCheckStates.get(position, false);
                        if (mCheckedItemCount == 1 && mCheckStates.valueAt(0)) {
                            int lastSelectedPosition = mCheckStates.keyAt(0);
                            ((Checkable) mData.get(lastSelectedPosition)).setChecked(false);
                            notifyItemChanged(lastSelectedPosition);
                        }
                        if (checked) {
                            mCheckStates.clear();
                            mCheckStates.put(position, true);
                            mCheckedItemCount = 1;
                            ((Checkable) mData.get(position)).setChecked(true);
                        } else {
                            mCheckStates.clear();
                            mCheckedItemCount = 0;
                        }
                    } else if (mChoiceMode == CHOICE_MODE_MULTIPLE) {
                        boolean checked = !mCheckStates.get(position, false);
                        mCheckStates.put(position, checked);
                        ((Checkable) mData.get(position)).toggle();
                        if (checked) {
                            mCheckedItemCount++;
                        } else {
                            mCheckedItemCount--;
                        }
                    }
                        notifyItemChanged(position);
                }
                if (mItemClickListener != null) {
                    mItemClickListener.onItemClick(position, v);
                }
            }
        });

完整代码：

public abstract class AbsRecycleAdapter<T> extends RecyclerView.Adapter<AbsRecycleAdapter.VH> {

    public static final int CHOICE_MODE_NONE = 0;
    public static final int CHOICE_MODE_SINGLE = 1;
    public static final int CHOICE_MODE_MULTIPLE = 2;
    public static final int INVALID_POSITION = -1;

    private SparseBooleanArray mCheckStates;
    private int mChoiceMode = CHOICE_MODE_NONE;
    private int mCheckedItemCount;

    private OnItemClickListener mItemClickListener;

    private List<T> mData;

    @Override
    public VH onCreateViewHolder(ViewGroup parent, int viewType) {
        final VH viewHolder = VH.get(parent, getLayoutId(viewType));

        viewHolder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int position = viewHolder.getAdapterPosition();

                if (mChoiceMode != CHOICE_MODE_NONE && mData.get(position) instanceof Checkable) {
                    if (mChoiceMode == CHOICE_MODE_SINGLE) {
                        boolean checked = !mCheckStates.get(position, false);
                        if (mCheckedItemCount == 1 && mCheckStates.valueAt(0)) {
                            int lastSelectedPosition = mCheckStates.keyAt(0);
                            ((Checkable) mData.get(lastSelectedPosition)).setChecked(false);
                            notifyItemChanged(lastSelectedPosition);
                        }
                        if (checked) {
                            mCheckStates.clear();
                            mCheckStates.put(position, true);
                            mCheckedItemCount = 1;
                            ((Checkable) mData.get(position)).setChecked(true);
                        } else {
                            mCheckStates.clear();
                            mCheckedItemCount = 0;
                        }
                    } else if (mChoiceMode == CHOICE_MODE_MULTIPLE) {
                        boolean checked = !mCheckStates.get(position, false);
                        mCheckStates.put(position, checked);
                        ((Checkable) mData.get(position)).toggle();
                        if (checked) {
                            mCheckedItemCount++;
                        } else {
                            mCheckedItemCount--;
                        }
                    }
                        notifyItemChanged(position);
                }
                if (mItemClickListener != null) {
                    mItemClickListener.onItemClick(position, v);
                }
            }
        });
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(VH holder, int position) {
        convert(holder, mData.get(position), position);
    }

    public abstract int getLayoutId(int viewType);

    public abstract void convert(VH holder, T data, int position);

    public void setOnItemClickListener(OnItemClickListener listener) {
        this.mItemClickListener = listener;
    }

    public void setChoiceMode(int choiceMode) {
        mChoiceMode = choiceMode;
        if (mChoiceMode != CHOICE_MODE_NONE) {
            if (mCheckStates == null) {
                mCheckStates = new SparseBooleanArray(0);
            }
        }
    }

    public boolean hasChecked() {
        return mCheckedItemCount > 0;
    }

    public int getCheckedItemPosition() {
        if (mChoiceMode == CHOICE_MODE_SINGLE && mCheckStates != null && mCheckStates.size() == 1) {
            return mCheckStates.keyAt(0);
        }
        return INVALID_POSITION;
    }

    public int getCheckedItemSize() {
        return mCheckedItemCount;
    }

    public void clearChoices() {
        if (mCheckStates != null) {
            mCheckStates.clear();
        }
        mCheckedItemCount = 0;
    }

    public SparseBooleanArray getCheckedItemPositions() {
        if (mChoiceMode != CHOICE_MODE_NONE) {
            return mCheckStates;
        }
        return null;
    }

    public void setData(List<T> beans) {
        if (null == mData) {
            mData = new ArrayList<>();
        }
        mData.clear();
        if (ValidateUtil.isValidate(beans)) {
            mData.addAll(beans);
        }       
    }

    public void addData(List<T> beans) {
        if (null == mData) {
            setData(beans);
        } else {
            mData.addAll(beans);
        }
    }

    public void addData(T t) {
        if (mData == null) {
            mData = new ArrayList<>();
        }
        if (!mData.contains(t)) {
            mData.add(t);
        }
    }

    public void remove(T t) {
        if (null != mData) {
            mData.remove(t);
        }
    }

    public List<T> getData() {
        return mData;
    }

    public void clear() {
        if (mData != null) {
            mData.clear();
        }
    }

    @Override
    public int getItemCount() {
        return mData == null ? 0 : mData.size();
    }

    public T getItem(int position) {
        if (mData != null) {
            return mData.get(position);
        }
        return null;
    }

    public interface OnItemClickListener {
        void onItemClick(int position, View v);
    }

    public static class VH extends RecyclerView.ViewHolder {
        private SparseArray<View> mViews;
        private View mConvertView;

        private VH(View v) {
            super(v);
            mConvertView = v;
            mViews = new SparseArray<>();
        }

        public static VH get(ViewGroup parent, int layoutId) {
            View convertView = LayoutInflater.from(parent.getContext()).inflate(layoutId, parent, false);
            return new VH(convertView);
        }

        public <T extends View> T getView(int id) {
            View v = mViews.get(id);
            if (v == null) {
                v = mConvertView.findViewById(id);
                mViews.put(id, v);
            }
            return (T) v;
        }

        public void setText(int id, String value) {
            TextView view = getView(id);
            view.setText(value);
        }

        public void setTextColor(int id, @ColorInt int color) {
            TextView view = getView(id);
            view.setTextColor(color);
        }

        public void setTextBackgroundResource(int id, @DrawableRes int resid) {
            TextView view = getView(id);
            view.setBackgroundResource(resid);
        }

        public void setBackgroundResource(int id, @DrawableRes int resId) {
            View view = getView(id);
            view.setBackgroundResource(resId);
        }

        public void setViewShow(int id, boolean isShow) {
            View view = getView(id);
            view.setVisibility(isShow ? View.VISIBLE : View.GONE);
        }

        public void setImageUrl(int id, String imageUrl) {
            ImageView imageView = getView(id);
            Glide.with(itemView.getContext())
                    .load(imageUrl)
                    .placeholder(R.mipmap.banner)
                    .error(R.mipmap.banner)
                    .into(imageView);
        }

        public void setImageResid(int id, int resourceId) {
            ImageView imageView = getView(id);
            imageView.setImageResource(resourceId);
        }

        public void setImageCircleAvatarUrl(int id, String imageUrl) {
            ImageView imageView = getView(id);
            Glide.with(itemView.getContext())
                    .load(imageUrl)
                    .placeholder(R.mipmap.avatar_default)
                    .error(R.mipmap.avatar_default)
                    .bitmapTransform(new GlideCircleTransform(itemView.getContext()))
                    .into(imageView);
        }

    }


}