本文參考：
http://blog.csdn.net/u014315849/article/details/52537700
http://blog.csdn.net/lmj623565791/article/details/45059587
http://blog.csdn.net/lmj623565791/article/details/51118836

Recycleview設(shè)置：

1.setLayoutManager() //設(shè)置布局管理器
2.setAdapter() //設(shè)置適配器
3.addItemDecoration() //添加裝飾（如分割線）
4.setItemAnimator() //設(shè)置動(dòng)畫（如添加蜡歹、刪除動(dòng)畫）

RecyclerView.LayoutManager是一個(gè)抽象類

實(shí)現(xiàn)類：
1.LinearLayoutManager 線性管理器，支持橫向捕捂、縱向迹栓。
2.GridLayoutManager 網(wǎng)格布局管理器
3.StaggeredGridLayoutManager 瀑布流式布局管理器

ViewHolder

ViewHolder是google在優(yōu)化ListView性能的技巧上就提到的塘装，雖然google并沒有強(qiáng)制使用，但事實(shí)上它已經(jīng)成為ListView的編寫規(guī)范。在RecyclerView上,ViewHolder的使用成為了一種強(qiáng)制手段了新蟆。
首先來看看ViewHolder的用法勘天，這是一個(gè)簡單的獲取String數(shù)組并展現(xiàn)到TextView上怔揩。通過數(shù)組的大小來創(chuàng)建item的數(shù)量。

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
    public String[] datas = null;
    public MyAdapter(String[] datas) {
        this.datas = datas;
    }
    //創(chuàng)建新View脯丝，被LayoutManager所調(diào)用
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
        View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.item,viewGroup,false);
        ViewHolder vh = new ViewHolder(view);
        return vh;
    }
    //將數(shù)據(jù)與界面進(jìn)行綁定的操作
    @Override
    public void onBindViewHolder(ViewHolder viewHolder, int position) {
        viewHolder.mTextView.setText(datas[position]);
    }
    //獲取數(shù)據(jù)的數(shù)量
    @Override
    public int getItemCount() {
        return datas.length;
    }
    //自定義的ViewHolder商膊，持有每個(gè)Item的的所有界面元素
    public static class ViewHolder extends RecyclerView.ViewHolder {
        public TextView mTextView;
        public ViewHolder(View view){
        super(view);
            mTextView = (TextView) view.findViewById(R.id.text);
        }
    }
}

介紹完RecycleView和ViewHolder，接下來我們看一下封裝目錄（參考鴻洋大神的github項(xiàng)目）

文件目錄

一宠进、封裝ViewHolder

public class BaseViewHolder extends RecyclerView.ViewHolder {

    //類似HashMap Android用SparseArray性能更高
    //管理view
    private SparseArray<View> mViews;
    //學(xué)習(xí)過ListView性能優(yōu)化的肯定知道 這是緩存視圖的
    private View mConvertView;
    private Context mContext;

    public BaseViewHolder(Context context, View itemView) {
        super(itemView);
        mContext = context;
        mConvertView = itemView;
        mViews = new SparseArray<>();
    }

    public static BaseViewHolder createViewHolder(Context context, View itemView) {
        return new BaseViewHolder(context, itemView);
    }

    public static BaseViewHolder createViewHolder(Context context,
                                              ViewGroup parent, int layoutId) {
        View itemView = LayoutInflater.from(context).inflate(layoutId, parent,
                false);
        return new BaseViewHolder(context, itemView);
    }

    /**
     * 通過ViewId獲取控件
     * @author dyb
     * @createTime 2017/3/17 22:54
     */
    public <T extends View> T getView(int viewId)
    {
        //先去SparseArray取view
        View view = mViews.get(viewId);//viewId 指的是 R.id.XXX這種 對(duì)應(yīng)一個(gè)viewId
        if (view == null)
        {
            view = mConvertView.findViewById(viewId);//SparseArray中沒有 則到convertView中直接findViewById
            mViews.put(viewId, view);//把view放進(jìn)SparseArray中
        }
        return (T) view;
    }

    public View getConvertView() {
        return mConvertView;
    }

    //以下為輔助方法（可略看）

    //設(shè)置TextView內(nèi)容
    public BaseViewHolder setText(int viewId, String text) {
        TextView tv = getView(viewId);
        tv.setText(text);
        return this;
    }

    //設(shè)置ImageView資源
    public BaseViewHolder setImageResource(int viewId, int resId) {
        ImageView view = getView(viewId);
        view.setImageResource(resId);
        return this;
    }

    //設(shè)置ImageView圖片Url
    public BaseViewHolder setImageUrl(int viewId, String imgUrl) {
        ImageView view = getView(viewId);
        Glide.with(view.getContext())
                .load(imgUrl)
                .diskCacheStrategy(DiskCacheStrategy.ALL)
                .placeholder(R.drawable.v)//設(shè)置加載中圖片
                .error(R.drawable.v)//設(shè)置加載失敗圖片
                .crossFade()//淡入淡出
                .fitCenter()//等比例拉伸填滿ImageView
                .into(view);
        return this;
    }

    //設(shè)置ImageView圖片Bitmap
    public BaseViewHolder setImageBitmap(int viewId, Bitmap bitmap) {
        ImageView view = getView(viewId);
        view.setImageBitmap(bitmap);
        return this;
    }

    //設(shè)置ImageView圖片Drawable
    public BaseViewHolder setImageDrawable(int viewId, Drawable drawable) {
        ImageView view = getView(viewId);
        view.setImageDrawable(drawable);
        return this;
    }

    //事件監(jiān)聽
    public BaseViewHolder setOnClickListener(int viewId,
                                         View.OnClickListener listener) {
        View view = getView(viewId);
        view.setOnClickListener(listener);
        return this;
    }

看一下BaseViewHolder完成的工作：

持有itemView 向外提供getViewByViewId方法

持有itemView：

由構(gòu)造器傳入itemView
或者傳入Context context晕拆，ViewGroup parent, int layoutId 調(diào)用LayoutInflater.from(context).inflate(layoutId, parent,false);生成itemView

向外提供getViewByViewId方法：

傳入viewId去獲取itemView具體的childrenView（findViewById）
為了提高效率 采用 SparesArray映射存儲(chǔ)

二、封裝MultiItemTypeAdapter（多類型item適配器）

你可能會(huì)問為什么不先封裝SingleItemTypeAdapter（單類型item適配器）
實(shí)際上SingleItemTypeAdapter是MultiItemTypeAdapter的特例材蹬，只要對(duì)MultiItemTypeAdapter進(jìn)行限定就能實(shí)現(xiàn)实幕。

public class MultiItemTypeAdapter<T> extends RecyclerView.Adapter<BaseViewHolder> {

    protected Context mContext;
    protected List<T> mDatas;

    protected ItemViewDelegateManager mItemViewDelegateManager;
    protected OnItemClickListener<T> mOnItemClickListener;
    public int offset = 0;

    public MultiItemTypeAdapter(Context context, List<T> datas) {
        mContext = context;
        mDatas = datas;
        mItemViewDelegateManager = new ItemViewDelegateManager();
    }

    public MultiItemTypeAdapter(Context context) {
        this(context, new ArrayList<T>());
    }

    @Override
    public int getItemViewType(int position) {
        if (!useItemViewDelegateManager())
            return super.getItemViewType(position);
        return mItemViewDelegateManager.getItemViewType(mDatas.get(position), position);
    }


    @Override
    public BaseViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        int layoutId = mItemViewDelegateManager.getItemViewLayoutId(viewType);
        BaseViewHolder holder = BaseViewHolder.createViewHolder(mContext, parent, layoutId);
        setListener(parent, holder, viewType);
        return holder;
    }

    public void convert(BaseViewHolder holder, T t) {
        mItemViewDelegateManager.convert(holder, t, holder.getAdapterPosition());
    }

    protected boolean isEnabled(int viewType) {
        return true;
    }


    protected void setListener(final ViewGroup parent, final BaseViewHolder viewHolder, int
            viewType) {
        if (!isEnabled(viewType))
            return;
        viewHolder.getConvertView().setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mOnItemClickListener != null) {
                    int position = viewHolder.getAdapterPosition();
                    mOnItemClickListener.onItemClick(v, viewHolder, mDatas.get(position - offset)
                            , position);
                }
            }
        });

        viewHolder.getConvertView().setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View v) {
                if (mOnItemClickListener != null) {
                    int position = viewHolder.getAdapterPosition();
                    return mOnItemClickListener.onItemLongClick(v, viewHolder, mDatas.get
                            (position - offset), position);
                }
                return false;
            }
        });
    }

    //將數(shù)據(jù)與界面進(jìn)行綁定的操作
    @Override
    public void onBindViewHolder(BaseViewHolder holder, int position) {
        convert(holder, mDatas.get(position));
    }

    //獲取數(shù)據(jù)的數(shù)量
    @Override
    public int getItemCount() {
        int itemCount = mDatas.size();
        return itemCount;
    }


    public List<T> getDatas() {
        return mDatas;
    }

    public MultiItemTypeAdapter addItemViewDelegate(ItemViewDelegate<T> itemViewDelegate) {
        mItemViewDelegateManager.addDelegate(itemViewDelegate);
        return this;
    }

    public MultiItemTypeAdapter addItemViewDelegate(int viewType, ItemViewDelegate<T>
            itemViewDelegate) {
        mItemViewDelegateManager.addDelegate(viewType, itemViewDelegate);
        return this;
    }

    protected boolean useItemViewDelegateManager() {
        return mItemViewDelegateManager.getItemViewDelegateCount() > 0;
    }

    public interface OnItemClickListener<T> {
        void onItemClick(View view, RecyclerView.ViewHolder holder, T o, int position);

        boolean onItemLongClick(View view, RecyclerView.ViewHolder holder, T o, int position);
    }

    public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
        this.mOnItemClickListener = onItemClickListener;
    }

    public void addDataAll(List data) {
        mDatas.addAll(data);
    }

    public void clearData() {
        mDatas.clear();
    }
}

public class ItemViewDelegateManager<T> {

    SparseArrayCompat<ItemViewDelegate<T>> delegates = new SparseArrayCompat();

    public int getItemViewDelegateCount() {
        return delegates.size();
    }

    public ItemViewDelegateManager<T> addDelegate(ItemViewDelegate<T> delegate) {
        int viewType = delegates.size();
        if (delegate != null) {
            delegates.put(viewType, delegate);
            viewType++;
        }
        return this;
    }

    public ItemViewDelegateManager<T> addDelegate(int viewType, ItemViewDelegate<T> delegate) {
        if (delegates.get(viewType) != null) {
            throw new IllegalArgumentException("An ItemViewDelegate is already registered for the" +
                    " viewType = " + viewType + ". Already registered ItemViewDelegate is " +
                    delegates
                    .get(viewType));
        }
        delegates.put(viewType, delegate);
        return this;
    }

    public ItemViewDelegateManager<T> removeDelegate(ItemViewDelegate<T> delegate) {
        if (delegate == null) {
            throw new NullPointerException("ItemViewDelegate is null");
        }
        int indexToRemove = delegates.indexOfValue(delegate);

        if (indexToRemove >= 0) {
            delegates.removeAt(indexToRemove);
        }
        return this;
    }

    public ItemViewDelegateManager<T> removeDelegate(int itemType) {
        int indexToRemove = delegates.indexOfKey(itemType);

        if (indexToRemove >= 0) {
            delegates.removeAt(indexToRemove);
        }
        return this;
    }

    public int getItemViewType(T item, int position) {
        int delegatesCount = delegates.size();
        for (int i = delegatesCount - 1; i >= 0; i--) {
            ItemViewDelegate<T> delegate = delegates.valueAt(i);
            if (delegate.isForViewType(item, position)) {
                return delegates.keyAt(i);
            }
        }
        throw new IllegalArgumentException("No ItemViewDelegate added that matches position=" +
                position + " in data source");
    }

    public void convert(BaseViewHolder holder, T item, int position) {
        int delegatesCount = delegates.size();
        for (int i = 0; i < delegatesCount; i++) {
            ItemViewDelegate<T> delegate = delegates.valueAt(i);

            if (delegate.isForViewType(item, position)) {
                delegate.convert(holder, item, position);
                return;
            }
        }
        throw new IllegalArgumentException("No ItemViewDelegateManager added that matches " +
                "position=" + position + " in data source");
    }


    public int getItemViewLayoutId(int viewType) {
        return delegates.get(viewType).getItemViewLayoutId();
    }

    public int getItemViewType(ItemViewDelegate itemViewDelegate) {
        return delegates.indexOfValue(itemViewDelegate);
    }
}

public interface ItemViewDelegate<T> {
    //向 Adapter 提供布局文件的 id 
    int getItemViewLayoutId();
    
    //判斷傳入的 item 是不是自己應(yīng)該處理的類型 
    boolean isForViewType(T item, int position);
    
    //綁定 holder 和數(shù)據(jù)
    void convert(BaseViewHolder holder, T t, int position);
}

重點(diǎn)：

一個(gè)item對(duì)應(yīng)一個(gè)ItemViewDelegate接口 實(shí)現(xiàn)

//向 Adapter 提供布局文件的 id
//判斷傳入的 item 是不是自己應(yīng)該處理的類型
//綁定 holder 和數(shù)據(jù)

ItemViewDelegateManager 管理ItemViewDelegate

用到了SparseArrayCompat來管理ItemViewDelegate

SparseArrayCompat其實(shí)是一個(gè)map容器,它使用了一套算法優(yōu)化了hashMap,可以節(jié)省至少50%的緩存.
缺點(diǎn)但是有局限性只針對(duì)下面類型.
key: Integer; value: object
因此當(dāng)HshMap()的key是Integer類型時(shí)推薦使用SparseArrayCompat(),用法與Map相似.

重點(diǎn)看這個(gè)數(shù)據(jù)綁定的邏輯

在數(shù)據(jù)綁定時(shí)遍歷SparseArrayCompat中的ItemViewDelegate
根據(jù)ItemViewDelegate實(shí)現(xiàn)的isForViewType(item, position)方法
來判斷是否由當(dāng)前ItemViewDelegate來處理數(shù)據(jù)綁定

Paste_Image.png

三、封裝SingleItemTypeAdapter

上面也說過了SingleItemTypeAdapter的實(shí)現(xiàn)只要對(duì)MultiItemTypeAdapter進(jìn)行一些限定：

getItemViewLayoutId 限定為一種layoutId

isForViewType 永遠(yuǎn)返回true

convert 數(shù)據(jù)綁定還是交由具體子類去實(shí)現(xiàn)

public abstract class SingleItemTypeAdapter<T> extends MultiItemTypeAdapter<T> {

    protected Context mContext;
    protected int mLayoutId;
    protected List<T> mDatas;
    protected LayoutInflater mInflater;

    public SingleItemTypeAdapter(final Context context, final int layoutId) {
        this(context, layoutId, new ArrayList<T>());
    }

    public SingleItemTypeAdapter(final Context context, final int layoutId, List<T> datas) {
        super(context, datas);
        mContext = context;
        mInflater = LayoutInflater.from(context);
        mLayoutId = layoutId;
        mDatas = datas;

        addItemViewDelegate(new ItemViewDelegate<T>() {
            @Override
            public int getItemViewLayoutId() {
                return layoutId;
            }

            @Override
            public boolean isForViewType(T item, int position) {
                return true;
            }

            @Override
            public void convert(BaseViewHolder holder, T t, int position) {
                SingleItemTypeAdapter.this.convert(holder, t, position);
            }
        });
    }

    protected abstract void convert(BaseViewHolder holder, T t, int position);
}