Android适配器之定义PagerAdapter万能适配器

一般使用pageAdapter需要实现getcount、isViewFromObject、instantiateItem、destroyItem等默认函数，其实完全可以抽取共有代码到父类当中。

/** * Created by Xiaoxuan948 on 2015/10/27. * Desc: * 提示：先给adapter设置数据，再绑定适配器    setAdapter会调用instantiateItem方法 */public class AbsUnityBasePageAdapter<T> extends PagerAdapter implements INotifyAdapterDataSetChange {    private static final UtilsLog lg = UtilsLog.getLogger(AbsUnityBasePageAdapter.class.getSimpleName());    private LayoutInflater layoutInflater;

private IAdapterDataModifyHelper<T> IAdapterataModifyHelper;

public AbsUnityBasePageAdapter() {        this.IAdapterataModifyHelper = new DataModifyHelper<>();    }

public IAdapterDataModifyHelper<T> getDataModifyHelper() {        this.IAdapterataModifyHelper.setNotifyAdapterDataSetChange(this);        return IAdapterataModifyHelper;    }

@Override    public void notifyAdapter() {        lg.e("notifyAdapter with dataSize:" + this.IAdapterataModifyHelper.getDataResources().size());        notifyDataSetChanged();    }

/*PagerAdapter默认必须实现方法*/    @Override    public boolean isViewFromObject(View view, Object object) {        lg.e("isViewFromObject:" + (view == object ? "true" : "false"));        return view == object;    }

@Override    public int getCount() {        return IAdapterataModifyHelper.getDataResources().size();    }

@Override    public Object instantiateItem(ViewGroup container, int position) {        if (layoutInflater == null) {            layoutInflater = LayoutInflater.from(container.getContext());        }        if (position >= IAdapterataModifyHelper.getDataResources().size()) {            lg.e("修正position：instantiateItem failed for position:" + position + " out of size:" + IAdapterataModifyHelper.getDataResources().size());            position = position % getDataModifyHelper().getDataResources().size();        }

lg.e("generateItemView for position:" + position);        View itemView = generateItemView(IAdapterataModifyHelper.getDataResources().get(position), layoutInflater, position);        container.addView(itemView);        return itemView;    }

@Override    //不调用会报错    public void destroyItem(ViewGroup container, int position, Object object) {        lg.e("destroyItem:" + position);        container.removeView((View) object);    }

/*自定义的抽象方法:基于Position构建View对象*/    protected View generateItemView(T itemEntity, LayoutInflater layoutInflater, int position) {        if (itemEntity instanceof View) {            return (View) IAdapterataModifyHelper.getDataResources().get(position);        } else {            throw new NullPointerException("DataResource Type is not View,so child class must Override");        }    }}

其中，IAdapterataModifyHelper当中封装对数据的增删改查等操作，并且已内部处理空指针异常。

instantiateItem中国，首先通过数组是否越界矫正position，调用generateItemView方法生成View对象并添加至container当中。在generateItemView实现当中，默认实现会判断当前数据集是否为View的集合，否则抛出异常，这里主要是为了强制开发人员重写generateItemView根据itemEntity生成View对象。

业务层使用方式如下：

adapter = new AbsUnityBasePageAdapter<String>() {

@Override    protected View generateItemView(String itemEntity, LayoutInflater layoutInflater, int position) {        lg.e("ViewPagerLabBaseAdapter generateItemView with position :" + position);        View itemRootView = layoutInflater.inflate(R.layout.simple_item_vertical, null);        ViewFindHelper viewFindHelper = new ViewFindHelper(itemRootView);        ImageView imgItemCommon = viewFindHelper.generateView(R.id.imgItemCommon);        imgItemCommon.setScaleType(ImageView.ScaleType.CENTER_CROP);        Glide.with(layoutInflater.getContext()).load(itemEntity).into(imgItemCommon);        return itemRootView;    }};

adapter.getDataModifyHelper().setDataResource(        "http://tupian.enterdesk.com/2013/mxy/12/10/15/3.jpg",        "http://pic1.nipic.com/2008-11-13/2008111384358912_2.jpg",        "http://img4.imgtn.bdimg.com/it/u=1249974208,2325623016&fm=21&gp=0.jpg",        "http://img0.imgtn.bdimg.com/it/u=1918423052,1540132432&fm=21&gp=0.jpg");vpActViewPager.setAdapter(adapter);

来自为知笔记(Wiz)