Android之工具通用的Adapter

在Android开发，特别是电商项目开发，使用RecyclerView、ListView、GridView是正常不过的了。一个项目下来，基本就是一直在写Adapter。刚开始写Adapter觉得没什么，无非就是ListView的继承BaseAdapter复写几个方法，getView里面使用ViewHolder模式；RecyclerView的就继承 RecyclerView.Adapter，复写onCreateViewHolder、onBindViewHolder然后实现便完事。但当我写到10遍、100遍甚至更多的时候，我就不想写了，反正都是这种写法，也没什么新的套路。于是我就想写一个RecyclerView、ListView、GridView通用的Adapter。

在文章最后附上DEMO

项目运行的实际效果：左边是ListView，右边是RecyclerView。

二、常见ListView、RecyclerView Adapter写法的例子

代码没什么难度可以随便看看就好。

public class ListViewAdapter extends BaseAdapter  {      private LayoutInflater mInflater;      private Context mContext;      private List mDatas;      private int mLayoutId;      public ListViewAdapter(Context context, List mDatas,int layoutId)      {          mInflater = LayoutInflater.from(context);          this.mContext = context;          this.mDatas = mDatas;          this.mLayoutId = layoutId;    }        @Override      public int getCount()      {          return mDatas.size();      }        @Override      public Object getItem(int position)      {          return mDatas.get(position);      }        @Override      public long getItemId(int position)      {          return position;      }        @Override      public View getView(int position, View convertView, ViewGroup parent)      {          ViewHolder viewHolder = null;          if (convertView == null)          {              convertView = mInflater.inflate(R.mLayoutId, parent, false);              viewHolder = new ViewHolder();              viewHolder.mTextView = (TextView) convertView                      .findViewById(R.id.id_tv);              convertView.setTag(viewHolder);          } else          {              viewHolder = (ViewHolder) convertView.getTag();          }          viewHolder.mTextView.setText(mDatas.get(position));          return convertView;      }        private final class ViewHolder      {          TextView mTextView;      }    }  private class RecyclerAdapter extends RecyclerView.Adapter {    private LayoutInflater mInflater;    private Context mContext;    private List mData;    private int mLayoutId;    public RecyclerAdapter(Context context, List data, int layoutId) {        mInflater = LayoutInflater.from(context);        this.mContext = context;        this.mData = data;        this.mLayoutId = layoutId;    }    @Override    public Holder onCreateViewHolder(ViewGroup parent, int viewType) {        View view = mInflater.inflate(mLayoutId, parent, false);        return new Holder(view);    }    @Override    public void onBindViewHolder(Holder holder, int position) {        holder.tv.setText(mData.get(position));    }    @Override    public int getItemCount() {        return mData.size();    }    class Holder extends RecyclerView.ViewHolder {        public TextView tv;        public Holder(View itemView) {            super(itemView);            tv = itemView.findViewById(R.id.tv);        }    }}

三、ListView、RecyclerView Adapter一些共性分析

1. 要显示的条目个数2. 要显示和条目对应的类型3. ListView、RecyclerView中，总共有多少个条目类型4. 根据不同的条目类型加载不同的View5. ListView复用条目convertView，RecyclerView自带ViewHoler复用

四、抽取RecyclerView、ListView、GridView适配器的基类

由于要通用RecyclerView、ListView、GridView只能将RecyclerView.Adapter和ListAdapter，SpinnerAdapter
这些都给实现了。里面也没多少个方法，其实也是很简单。至于一些方法的实现我考贝BaseAdapter的实现，
大家可以去看看BaseAdapter的源码。

public class BaseAdapter extends RecyclerView.Adapter implements ListAdapter, SpinnerAdapter {    private final DataSetObservable mDataSetObservable = new DataSetObservable();    // RecyclerView========================================================================    @Override    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {        return null;    }    // RecyclerView    @Override    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {    }    // RecyclerView    @Override    public int getItemCount() {        return 0;    }    // RecyclerView========================================================================    // ListView========================================================================    @Override    public boolean areAllItemsEnabled() {        return true;    }    @Override    public boolean isEnabled(int position) {        return true;    }    @Override    public void registerDataSetObserver(DataSetObserver observer) {        mDataSetObservable.registerObserver(observer);    }    @Override    public void unregisterDataSetObserver(DataSetObserver observer) {        mDataSetObservable.unregisterObserver(observer);    }    public void notifyListDataSetChanged() {        mDataSetObservable.notifyChanged();    }    @Override    public Object getItem(int position) {        return null;    }    @Override    public View getView(int position, View convertView, ViewGroup parent) {        return null;    }    @Override    public int getViewTypeCount() {        return 1;    }    @Override    public int getItemViewType(int position) {        return 0;    }    @Override    public int getCount() {        return 0;    }        @Override    public boolean isEmpty() {        return getCount() == 0;    }    @Override    public View getDropDownView(int position, View convertView, ViewGroup parent) {        return getView(position, convertView, parent);    }}

五、抽取支持ListView、 GridView、 RecyclerView多条目的共性

public interface QuickMultiSupport {    /**     * 获取多条目View类型的数量     */    int getViewTypeCount();    /**     * 根据数据，获取多条目布局ID     */    int getLayoutId(T data);    /**     * 根据数据，获取多条目的ItemViewType     */    int getItemViewType(T data);    /**     * 是否合并条目-->>使用RecyclerView时，如果无效，请用原生的RecyclerView     */    boolean isSpan(T data);

六、打造RecyclerView、ListView、GridView通用的适配器

由于要同时适配RecyclerView、ListView、GridView，也就等于把两个Adapter的实现放在一个类里面
所以代码有点多，但代码我已分开，很容易看。
还有数据都复制出来的，条目的增删改查都在Adapter里面。

/** * RecyclerView、ListView、GridView通用的适配器 */public abstract class QuickAdapter extends BaseAdapter {    private Context mContext;    private List mData;    private int mLayoutId;    private QuickMultiSupport mSupport;    private boolean isRecycler;    private int mPosition;    public QuickAdapter(Context context, List data, int layoutId) {        this.mContext = context;        this.mData = data == null ? new ArrayList() : new ArrayList(data);        this.mLayoutId = layoutId;    }    public QuickAdapter(Context context, List data, QuickMultiSupport support) {        this(context, data, 0);        this.mSupport = support;    }    @Override    public int getCount() {        return mData.size();    }    @Override    public T getItem(int position) {        return mData.get(position);    }    @Override    public long getItemId(int position) {        return position;    }    @Override    public View getView(int position, View convertView, ViewGroup parent) {        QuickViewHolder holder;        if (convertView == null) {            int layoutId = mLayoutId;            // 多条目的            if (mSupport != null) {                layoutId = mSupport.getLayoutId(mData.get(position));            }            // 创建ViewHolder            holder = createListHolder(parent, layoutId);        } else {            holder = (QuickViewHolder) convertView.getTag();            // 防止失误，还要判断            if (mSupport != null) {                int layoutId = mSupport.getLayoutId(mData.get(position));                // 如果布局ID不一样，又重新创建                if (layoutId != holder.getLayoutId()) {                    // 创建ViewHolder                    holder = createListHolder(parent, layoutId);                }            }        }        // 绑定View的数据        convert(holder, mData.get(position), position);        return holder.itemView;    }    /**     * 创建ListView的Holer     */    @NonNull    private QuickViewHolder createListHolder(ViewGroup parent, int layoutId) {        QuickViewHolder holder;        View itemView = LayoutInflater.from(mContext).inflate(layoutId, parent, false);        holder = new QuickViewHolder(itemView, layoutId);        itemView.setTag(holder);        return holder;    }    /**     * ViewType的数量     */    @Override    public int getViewTypeCount() {        // 多条目的        if (mSupport != null) {            return mSupport.getViewTypeCount() + super.getViewTypeCount();        }        return super.getViewTypeCount();    }    /**     * 这个方法是共用的     */    @Override    public int getItemViewType(int position) {        mPosition = position;        // 多条目的        if (mSupport != null) {            return mSupport.getItemViewType(mData.get(position));        }        return super.getItemViewType(position);    }    // RecyclerView=================================================================================    @Override    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {        isRecycler = true;        // 如果是多条目，viewType就是布局ID        View view;        if (mSupport != null) {            int layoutId = mSupport.getLayoutId(mData.get(mPosition));            view = LayoutInflater.from(mContext).inflate(layoutId, parent, false);        } else {            view = LayoutInflater.from(mContext).inflate(mLayoutId, parent, false);        }        QuickViewHolder holder = new QuickViewHolder(view);        return holder;    }    @Override    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {        if (holder instanceof QuickViewHolder) {            convert((QuickViewHolder) holder, mData.get(position), position);        }    }    @Override    public int getItemCount() {        return mData.size();    }    @Override    public void onAttachedToRecyclerView(RecyclerView recyclerView) {        if (mSupport == null || recyclerView == null) {            return;        }        RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();        if (layoutManager instanceof GridLayoutManager) {            final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;            final GridLayoutManager.SpanSizeLookup spanSizeLookup = gridLayoutManager.getSpanSizeLookup();            // 如果设置合并单元格就占用SpanCount那个多个位置            gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {                @Override                public int getSpanSize(int position) {                    if (mSupport.isSpan(mData.get(position))) {                        return gridLayoutManager.getSpanCount();                    } else if (spanSizeLookup != null) {                        return spanSizeLookup.getSpanSize(position);                    }                    return 1;                }            });            gridLayoutManager.setSpanCount(gridLayoutManager.getSpanCount());        }    }    @Override    public void onViewAttachedToWindow(RecyclerView.ViewHolder holder) {        if (mSupport == null) {            return;        }        int position = holder.getLayoutPosition();        // 如果设置合并单元格        if (mSupport.isSpan(mData.get(position))) {            ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams();            if (lp != null && lp instanceof StaggeredGridLayoutManager.LayoutParams) {                StaggeredGridLayoutManager.LayoutParams p = (StaggeredGridLayoutManager.LayoutParams) lp;                p.setFullSpan(true);            }        }    }    // RecyclerView=================================================================================    /**     * 绑定View的数据     */    protected abstract void convert(QuickViewHolder holder, T item, int position);    //==========================================数据相关================================================    public void add(T elem) {        mData.add(elem);        notifyData();    }    public void addAll(List data) {        mData.addAll(data);        notifyData();    }        public void addFirst(T elem) {        mData.add(0, elem);        notifyData();    }        public void set(T oldElem, T newElem) {        set(mData.indexOf(oldElem), newElem);        notifyData();    }        public void set(int index, T elem) {        mData.set(index, elem);        notify();    }    public void remove(T elem) {        mData.remove(elem);        notifyData();    }    public void remove(int index) {        mData.remove(index);        notifyData();    }    public void replaceAll(List elem) {        mData.clear();        mData.addAll(elem);        notifyData();    }    /**     * 清除     */    public void clear() {        mData.clear();        notifyData();    }    private void notifyData() {        if (isRecycler) {            notifyDataSetChanged();        } else {            notifyListDataSetChanged();        }    }    public List getData() {        return mData;    }}

七、通用ViewHolder的抽取

ViewHolder最主要就是实现平时常用的方法，比如：点击事件、长按事件、给TextView设置内容等等
如果不够，实际开发可以自己添加。

public class QuickViewHolder extends RecyclerView.ViewHolder {    private SparseArray> mViews;    private int mLayoutId;    public QuickViewHolder(View itemView) {        this(itemView, -1);    }    public QuickViewHolder(View itemView, int layoutId) {        super(itemView);        mViews = new SparseArray<>();        this.mLayoutId = layoutId;    }    public int getLayoutId() {        return mLayoutId;    }    /**     * 设置条目的点击事件     */    public QuickViewHolder setOnClickListener(View.OnClickListener listener) {        itemView.setOnClickListener(listener);        return this;    }    /**     * 设置条目的长按事件     */    public QuickViewHolder setOnLongClickListener(View.OnLongClickListener listener) {        itemView.setOnLongClickListener(listener);        return this;    }    /**     * 设置View的点击事件     *     * @return     */    public QuickViewHolder setOnClickListener(int viewId, View.OnClickListener listener) {        View view = getView(viewId);        if (view != null) {            view.setOnClickListener(listener);        }        return this;    }    /**     * 获取条目的View     */    public View getView() {        return itemView;    }    /**     * 根据ID获取条目里面的View     */    public  T getView(int viewId) {        WeakReference viewWeakReference = mViews.get(viewId);        View view = null;        if (viewWeakReference == null) {            view = itemView.findViewById(viewId);            if (view != null) {                mViews.put(viewId, new WeakReference<>(view));            }        } else {            view = viewWeakReference.get();        }        return (T) view;    }    public QuickViewHolder setText(int viewId, CharSequence text) {        TextView tv = getView(viewId);        if (tv != null && !TextUtils.isEmpty(text)) {            tv.setText(text);        }        return this;    }    /**     * 设置图片背景颜色     */    public QuickViewHolder setTextColor(int viewId, int color) {        TextView view = getView(viewId);        if (view != null) {            view.setTextColor(color);        }        return this;    }    /**     * 设置控件是否可见     */    public QuickViewHolder setVisible(int viewId, int visible) {        View view = getView(viewId);        view.setVisibility(visible);        return this;    }    /**     * 设置控件选中     */    public QuickViewHolder setChecked(int viewId, boolean checked) {        Checkable view = getView(viewId);        view.setChecked(checked);        return this;    }    /**     * 设置控件背景     */    public QuickViewHolder setBackgroundRes(int viewId, int backgroundRes) {        View view = getView(viewId);        view.setBackgroundResource(backgroundRes);        return this;    }    /**     * 设置图片     */    public QuickViewHolder setImageResource(int viewId, int imageResId) {        ImageView imageView = getView(viewId);        imageView.setImageResource(imageResId);        return this;    }    /**     * 设置图片     */    public QuickViewHolder setImageBitmap(int viewId, Bitmap bitmap) {        ImageView imageView = getView(viewId);        imageView.setImageBitmap(bitmap);        return this;    }}

八、项目实际使用

我只写了多条目的测试使用，对于一种类型的写法更为简单，我就不写了。

public class MainActivity extends AppCompatActivity {    private List mData = new ArrayList<>();    private QuickMultiSupport mQuickSupport;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initData();        initViews();    }    /**     * 多条目的ViewType     */    public interface IViewType {        int getItemViewType();    }    private void initData() {        for (int i = 0; i < 199; i++) {            if (i % 10 == 0) {                MultiBean bean = new MultiBean();                bean.name = "mData--------" + i;                mData.add(bean);            } else {                MultiBean1 bean = new MultiBean1();                bean.name = "mData--------" + i;                mData.add(bean);            }        }        // 多条目支持        mQuickSupport = new QuickMultiSupport() {            // 条目总共两种类型            @Override            public int getViewTypeCount() {                return 2;            }            // 根据不用的JavaBean返回不同的布局            @Override            public int getLayoutId(IViewType data) {                if (data instanceof MultiBean) {                    return R.layout.item_list1;                }                return R.layout.item_list;            }            @Override            public int getItemViewType(IViewType data) {                return data.getItemViewType();            }            @Override            public boolean isSpan(IViewType data) {                // 是否占用一个条目，针对RecyclerView                if (data instanceof MultiBean) {                    return true;                }                return false;            }        };    }    private void initViews() {        ListView listView = findViewById(R.id.list_view);        RecyclerView recyclerView = findViewById(R.id.recycler_view);        // ListView设置Adapter        listView.setAdapter(new CommAdapter(this, mData, mQuickSupport));        // RecyclerView设置Adapter        recyclerView.setLayoutManager(new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL));        recyclerView.setAdapter(new CommAdapter(this, mData, mQuickSupport));    }    class CommAdapter extends QuickAdapter {        public CommAdapter(Context context, List data, int layoutId) {            super(context, data, layoutId);        }        public CommAdapter(Context context, List data, QuickMultiSupport support) {            super(context, data, support);        }        @Override        protected void convert(QuickViewHolder holder, IViewType item, final int position) {            holder.setText(R.id.tv, item.toString());            holder.setOnClickListener(new View.OnClickListener() {                @Override                public void onClick(View v) {                    // 点击移除当前条目                    remove(position);                }            });        }    }}

至此无论是RecyclerView还是ListView终于只用一个Adapter，

Demo下载

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