unsplash

背景：为了使项目更加整洁，利于开发，后期管理，需要打造一款通用的recyclerview的适配器，功能要求：满足不同数据内容的适配；数据绑定部分简洁易懂；点击事件和长按事件监听；多条目布局的简单实现。学习于 鸿洋 的为RecyclerView打造通用Adapter 让RecyclerView更加好用这篇博文。

不同数据类型的适配使用泛型；
传入布局id动态填充；
在抽象方法中自定义数据绑定部分；
接口回调事项点击和长按事件；

/**
 * Created by whstywh on 2017/7/31.
 * GitHub：https://github.com/whstywh
 * email：whstywh@gmail.com
 * description：通用Adapter
 */

public abstract class CommonRAdapter<T> extends RecyclerView.Adapter<CommonRAdapter.CommonViewHolder> {

    protected Context mContext;
    protected List<T> mList;
    protected int mLayoutId;
    protected LayoutInflater mLayoutInflater;
    public OnItemClickListener mItemClickListener;
    public OnLongClickListener mLongClickListener;

    public CommonRAdapter(Context context, List<T> list, int layoutId) {
        this.mContext = context;
        this.mList = list;
        this.mLayoutId = layoutId;
        mLayoutInflater = LayoutInflater.from(mContext);
    }


    @Override
    public CommonViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = mLayoutInflater.inflate(mLayoutId, parent, false);
        CommonViewHolder holder = new CommonViewHolder(view, mContext);
        return holder;
    }

    @Override
    public void onBindViewHolder(CommonRAdapter.CommonViewHolder holder, int position) {
        convert(holder, mList.get(position));
    }

    public abstract void convert(CommonViewHolder holder, T itemData);

    @Override
    public int getItemCount() {
        return mList.size();
    }

    public interface OnItemClickListener {
        void itemClick();
    }

    public interface OnLongClickListener {
        boolean longClick();
    }


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

    public void setOnLongClickListener(OnLongClickListener longClickListener) {
        this.mLongClickListener = longClickListener;
    }
}

使用SparseArray稀疏数组缓存view：因为SparseArray也是通过键值对储存，相比map集合有着占用内存小的优点，用来替代Map<Integer,Objecty>;
通过传入item中的viewId来获取view：如果数组中没有，则findViewById并且缓存至数组中，方便下次获取；
由于item的布局大多为TextView，ImageView，所以封装统一的set()，get()方法；

    /***
     * ViewHolder
     */
    public class CommonViewHolder extends RecyclerView.ViewHolder {

        private SparseArray<View> mSparseArray;

        public CommonViewHolder(View itemView, Context context) {
            super(itemView);
            mSparseArray = new SparseArray<>();
            itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    if (mItemClickListener != null) {
                        mItemClickListener.itemClick();
                    }
                }
            });
            itemView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View v) {
                    return mLongClickListener == null ? false : mLongClickListener.longClick();
                }
            });
        }

        public CommonViewHolder setText(int viewId, CharSequence charSequence) {
            TextView textView = getView(viewId);
            textView.setText(charSequence);
            return this;
        }

        public CommonViewHolder setImage(int viewId, CharSequence charSequence) {
            ImageView imageView = getView(viewId);
            Glide.with(mContext).load(charSequence).into(imageView);
            return this;
        }


        private <T extends View> T getView(int viewId) {
            View view = mSparseArray.get(viewId);
            if (view == null) {
                view = itemView.findViewById(viewId);
                mSparseArray.put(viewId, view);
            }
            return (T) view;
        }
    }

多布局是通过自己来分配布局来实现的，定义接口并且在实例adapter的时候传入实现对象，
自定义返回的itemType，layoutId；

/**
 * Created by whstywh on 2017/7/31.
 * GitHub：https://github.com/whstywh
 * email：whstywh@gmail.com
 * description：通用适配器—多条目布局
 */

public abstract class MultiItemCommonAdapter<T> extends CommonRAdapter<T> {

    protected MultiItemTypeSupport<T> mMultiItemTypeSupport;

    @Override
    public int getItemViewType(int position) {
        return mMultiItemTypeSupport.getItemViewType(position, mList.get(position));
    }

    public MultiItemCommonAdapter(Context context, List<T> list, int layoutId, MultiItemTypeSupport<T> multiTypeSupport) {
        super(context, list, layoutId);
        this.mMultiItemTypeSupport = multiTypeSupport;
    }

    @Override
    public CommonRAdapter.CommonViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        mLayoutId = mMultiItemTypeSupport.getLayoutId(viewType);
        View view = mLayoutInflater.inflate(mLayoutId, parent, false);
        CommonViewHolder holder = new CommonViewHolder(view, mContext);
        return holder;
    }
//接口
    public interface MultiItemTypeSupport<T> {
        int getLayoutId(int itemType);

        int getItemViewType(int position, T t);
    }
}