打造RecyclerView萬能適配器

騷年,如果你還在用ListView趕緊換RecyclerView吧,用了之后你會發現從此你再也不想用ListView了。下面我說說兩者的優缺點,listView簡單易用,google工程師已經把很多功能封裝好了,比如點擊事件,分割線,頭部,尾部。缺點:性能差,可拓展性不好。RecyclerView用法稍微復雜。但是功能強大,可拓展性好。依靠LayoutManager(通俗叫法布局管理器)可以實現多種效果,比如listview,graidview,以及瀑布流效果。并且可以設置動畫,點擊效果那叫一個狂拽酷炫啊。Google工程師呢也是留下了很多東西讓開發者自己去發揮。條目點擊我們得自己寫,最惡心的是分割線和grid形式的間距設置有點惡心。還有一點我發現對于api22以上(開發時的編譯版本)和api22以下是有差異的。比如我要設置recyclerview高度為wrap_content,但是視圖并沒有包裹而是占了一個頁面。解決方式是寫一個可包裹的L愛有天Mannager。對于api22以上不需要考慮,可以正常設置。這點算一個版本bug吧。那么無論listview還是recyclerview最重要的就是適配器了。終于講到正題了。那么下面我們來聊聊Adapter
適配器其實就是把數據適配成view。通俗點說就像是一個模具,你把料(數據)放進來,我們倒個模出來。平時開發中這個列表需求是很多的,那么意味著我們要用很多次這種控件。每次用我們又得寫適配器。是不是很煩,一大堆相同代碼。寫得手疼,于是想著要把這些相同的代碼是不是可以做個封裝,我們只需要把布局,把數據這些不同業務提供給外面實現。基于這個想法,有了今天我們要講的這個主題。

業務需求1.普通常見列表。不包含頭尾。要求只給一個布局,一些數據可以實現需求。

分析:數據寫死肯定是不行的,這里采用泛型設計。數據設置我們可以寫一個set方法設置。布局得抽象出去實現,還有數據和view之間的綁定也得抽象出去。holder也需要根據布局來重新寫。

適配器代碼如下:

public abstract class BaseRecyclerViewAdapter<T> extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
    protected Context mContext;
    protected final LayoutInflater inflater;
    protected List<T> mDatas;
    protected int mLayoutId;
    private OnItemClickListener onItemClickListener;

    public BaseRecyclerViewAdapter(Context mContext, int layoutId, List<T> datas) {
        this.mContext = mContext;
        this.mLayoutId = layoutId;
        this.mDatas = datas;
        inflater = LayoutInflater.from(mContext);
    }

    /*數據操作*/
    public void addData(T bean) {
        mDatas.add(bean);
        notifyDataSetChanged();
    }

    public void addDatas(List<T> datas) {
        mDatas.addAll(datas);
        notifyDataSetChanged();
    }

    public void remove(int index) {
        if (index < 0 && index > mDatas.size()) {
            throw new IndexOutOfBoundsException("index not right");
        }
        else mDatas.remove(index);
        notifyDataSetChanged();
    }

    public void removeAll() {
        mDatas.clear();
        notifyDataSetChanged();
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = inflater.inflate(mLayoutId, parent, false);
        return onCreatHolder(view);
    }


    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        final int pos = getRealPosition(holder);
        final T bean = mDatas.get(pos);
        onBindHolder(holder, pos, bean);
        holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (onItemClickListener != null) {
                    onItemClickListener.onItemClick(pos, bean);
                }

            }
        });
    }

    private int getRealPosition(RecyclerView.ViewHolder holder) {
        return holder.getLayoutPosition();
    }

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

    /*寫一個接口回調點擊事件*/
    public interface OnItemClickListener<T> {
        void onItemClick(int position, T bean);
    }

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


    /**
     * @param view
     * @return 抽象出去
     */
    public abstract RecyclerView.ViewHolder onCreatHolder(View view);

    protected abstract void onBindHolder(RecyclerView.ViewHolder holder, int pos, T bean);
}

2.使用過程中發現ViewHolder以及查找id并不好用,把上面的適配器升級一下,我們來一個BaseViewHolder把一些數據裝配操作也封裝起來。BaseViewHolder封裝了一些常用控件的數據操作,事件監聽等。基于這些想法,我們再做升級改造。

public abstract class BaseRecyclerAdapter<T> extends RecyclerView.Adapter<BaseViewHolder> {


    protected Context mContext;
    protected List<T> mDatas;
    private int totalList;

    private int itemLayoutId;
    private OnItemClickListener onItemClickListener;
    private OnItemLongClickListener onItemLongClickListener;
    private final LayoutInflater mInflater;
    private static final int TYPE_HEAD = 0;
    private static final int TYPE_ITEM = 1;
    private static final int TYPE_FOOT = 2;
    private boolean isScrolling = true;  //false表示滑動,true表示不滑動
    private View headerView, footerView;  //頭和尾的view


    public BaseRecyclerAdapter(Context ctx, int itemLayoutId, List<T> list) {
        this.mContext = ctx;
        this.itemLayoutId = itemLayoutId;
        mDatas = (list != null) ? list : new ArrayList<T>();
        mInflater = LayoutInflater.from(ctx);
    }
    /*數據操作*/
    public void addData(T bean) {
        mDatas.add(bean);
        notifyDataSetChanged();
    }

    public void addDatas(List<T> datas) {
        mDatas.addAll(datas);
        notifyDataSetChanged();
    }

    public void remove(int index) {
        if (index < 0 && index > mDatas.size()) {
            throw new IndexOutOfBoundsException("index not right");
        }
        else mDatas.remove(index);
        notifyDataSetChanged();
    }

    public void removeAll() {
        mDatas.clear();
        notifyDataSetChanged();
    }

    public void setFooterView(View view) {
        this.footerView = view;
    }

    public void setHeaderView(View view) {
        this.headerView = view;
    }

    @Override
    public BaseViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        if (viewType == TYPE_HEAD && headerView != null) {
            return new BaseViewHolder(mContext, headerView);
        }
        if (viewType == TYPE_FOOT && footerView != null) {
            return new BaseViewHolder(mContext, footerView);
        }

        View view = mInflater.inflate(itemLayoutId, parent, false);
        return new BaseViewHolder(mContext, view);
    }

    @Override
    public void onBindViewHolder(BaseViewHolder holder, int position) {
        if (getItemViewType(position) != TYPE_ITEM) {
            //如果不是正常的Item,就不去綁定數據
            return;
        }
        final int p = getRealPosition(position);
        convert(holder, p, mDatas.get(p));
        if (onItemClickListener != null) {
            holder.itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    onItemClickListener.onItemClick(p, mDatas.get(p));
                }
            });
        }
        if (onItemLongClickListener != null) {
            holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View view) {
                    onItemLongClickListener.onLongItemClick(p, mDatas.get(p));
                    return true;
                }
            });
        }


    }


    private int getRealPosition(int position) {
        return headerView == null ? position : position - 1;
    }

    @Override
    public int getItemCount() {
        if (mDatas == null) {
            return 0;
        }
        if (headerView != null && footerView != null) {
            //頭尾都不為空
            totalList = mDatas.size() + 2;
        } else if (headerView == null && footerView == null) {
            //頭尾都為空
            totalList = mDatas.size();
        } else {
            //頭尾有一個不為空
            totalList = mDatas.size() + 1;
        }
        return totalList;
    }

    @Override
    public int getItemViewType(int position) {
        if (position == 0 && headerView != null) {
            return TYPE_HEAD;
        } else if (position + 1 == getItemCount() && footerView != null) {
            return TYPE_FOOT;
        } else {
            return TYPE_ITEM;
        }
    }


    /*
    * 需要根據實際情況設置的部分抽象出去
    * */
    protected abstract void convert(BaseViewHolder holder, int p, T t);

    /*接口回調點擊和長按事件*/
    public interface OnItemClickListener<T> {
        void onItemClick(int position, T bean);
    }

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

    public interface OnItemLongClickListener<T> {
        void onLongItemClick(int position, T bean);
    }

    public void setOnItemLongClickListener(OnItemLongClickListener onLongClickListener) {
        this.onItemLongClickListener = onLongClickListener;
    }
}

BaseViewHolder的代碼如下

public class BaseViewHolder extends RecyclerView.ViewHolder {

    /*
    * 數據量不大,最好在千級以內
    * key必須為int類型,這中情況下的HashMap可以用SparseArray代替:比如
    * HashMap<Integer, Object> map = new HashMap<>();
    * 用SparseArray代替:
    * SparseArray<Object> array = new SparseArray<>();
    * */
    private SparseArray<View> mViews; //集合類,layout里包含的View,以view的id作為key,value是view對象
    private Context mContext;

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

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

    //  封裝一些常用的控件  根據對應的id獲取控件
    public TextView getTextView(int viewId) {
        return (TextView) getView(viewId);
    }

    public Button getButton(int viewId) {
        return (Button) getView(viewId);
    }

    public ImageView getImageView(int viewId) {
        return (ImageView) getView(viewId);
    }

    public ImageButton getImageButton(int viewId) {
        return (ImageButton) getView(viewId);
    }

    public EditText getEditText(int viewId) {
        return (EditText) getView(viewId);
    }

    public BaseViewHolder setText(int viewId, String value) {
        TextView textView = getView(viewId);
        textView.setText(value);
        return this;
    }

    public BaseViewHolder setBitmapImage(int viewId, int imageId) {
        ImageView iv = getView(viewId);
        iv.setImageResource(imageId);
        return this;
    }

    public BaseViewHolder setImagebyUrl(int viewId, String url) {
        ImageView iv = getView(viewId);
        ShowImageUtils.showImageView(mContext, url, iv);
        return this;
    }

    public BaseViewHolder setCircleImagebyUrl(int viewId, String url) {
        ImageView iv = getView(viewId);
        ShowImageUtils.showImageViewToCircle(mContext, R.mipmap.ic_launcher, url, iv);
        return this;
    }

    public BaseViewHolder setBackground(int viewId, int resId) {
        View view = getView(viewId);
        view.setBackgroundResource(resId);
        return this;
    }

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

}

3.使用中發現對于GridLayout,瀑布流這種會導致頭部和尾部變成其中的item。這顯然不是我們想要的。那么就對著兩種情況特殊處理。
怎么做呢?在adapter中重寫onAttachedToRecyclerView
但是這種做法無法解決瀑布流的問題,對于StaggeredGridLayoutManager我們需要重寫onViewAttachedToWindow

 /**
     * @param recyclerView 處理GridLayoutManager
     */
    @Override
    public void onAttachedToRecyclerView(RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);
        RecyclerView.LayoutManager manager = recyclerView.getLayoutManager();
        if (manager instanceof GridLayoutManager) {
            final GridLayoutManager gridLayoutManager = (GridLayoutManager) manager;
            //setSpanSizeLookup的getSpanSize可以控制列數
            gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
                @Override
                public int getSpanSize(int position) {
                    return (getItemViewType(position) == TYPE_HEAD || getItemViewType(position) == TYPE_FOOT) ? gridLayoutManager.getSpanCount() : 1;
                }
            });
        }/*else if (manager instanceof StaggeredGridLayoutManager) {  StaggeredGridLayoutManager并沒有setSpanSizeLookup這個方法,所以此路不通
            StaggeredGridLayoutManager staggeredManager = (StaggeredGridLayoutManager) manager;

        }*/
    }

    /**
     * @param holder
     * 處理StaggerdGridLayoutManager
     */
    @Override
    public void onViewAttachedToWindow(BaseViewHolder holder) {
        super.onViewAttachedToWindow(holder);
        ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams();
        if (lp != null && lp instanceof StaggeredGridLayoutManager.LayoutParams) {
            StaggeredGridLayoutManager.LayoutParams p = (StaggeredGridLayoutManager.LayoutParams) lp;
            if (headerView != null && holder.getLayoutPosition() == 0) {
                p.setFullSpan(true);
            }

            if (footerView != null && holder.getLayoutPosition() == getItemCount() - 1) {
                p.setFullSpan(true);
            }
        }

    }

至此,我們的目的就達到了,使用起來超簡單可以繼承BaseRecyclerAdapter,也可以直接用它的匿名內部類。這里就不贅述了。使用本類可以減少你Adapter百分之70的代碼,趕緊拿去擼吧!

最后編輯于
?著作權歸作者所有,轉載或內容合作請聯系作者
平臺聲明:文章內容(如有圖片或視頻亦包括在內)由作者上傳并發布,文章內容僅代表作者本人觀點,簡書系信息發布平臺,僅提供信息存儲服務。

推薦閱讀更多精彩內容