android仿Adapter实现自定义PagerAdapter方法示例

private class ViewPagerAdapter extends PagerAdapter {      // 获取要滑动的控件的数量，在这里我们以滑动的广告栏为例，那么这里就应该是展示的广告图片的ImageView数量     @Override     public int getCount() {       return images.size();     }      // 来判断显示的是否是同一张图片，这里我们将两个参数相比较返回即可     @Override     public boolean isViewFromObject(View arg0, Object arg1) {       return arg0 == arg1;     }      // PagerAdapter只缓存三张要显示的图片，如果滑动的图片超出了缓存的范围，就会调用这个方法，将图片销毁     @Override     public void destroyItem(ViewGroup view, int position, Object object) {       view.removeView(images.get(position));     }      // 当要显示的图片可以进行缓存的时候，会调用这个方法进行显示图片的初始化，我们将要显示的ImageView加入到ViewGroup中，然后作为返回值返回即可     @Override     public Object instantiateItem(ViewGroup view, int position) {       view.addView(images.get(position));       return images.get(position);     }   } 

public abstract class EjBasePagerAdapter<T> extends PagerAdapter { protected List<T> list; protected SparseArray<EjBasePagerHolder<T>> sparseArray; public EjBasePagerAdapter(List<T> list){  this.list = list;  sparseArray = new SparseArray<>(); } @Override public int getCount() {  return list.size(); } public String getIcon(int position){  return null; } @Override public Object instantiateItem(ViewGroup container, int position) {  EjBasePagerHolder<T> holder = sparseArray.get(getSparsePosition(position));  if(null == holder){   holder = onBundHolder(container);   holder.setPosition(position);   holder.bindDada(list.get(position),position);   sparseArray.put(getSparsePosition(position),holder);  }  View view = holder.itemView;  container.addView(view);  return view; } @Override public void notifyDataSetChanged() {  sparseArray.clear();  super.notifyDataSetChanged(); } protected int getSparsePosition(int position){  return (position+10)*2; } @Override public void destroyItem(ViewGroup container, int position, Object object) {  container.removeView((View) object); } protected View inflate(int resorce, ViewGroup viewGroup) {  return LayoutInflater.from(viewGroup.getContext()).inflate(resorce, viewGroup, false); } @Override public boolean isViewFromObject(View view, Object object) {  return view == object; } protected abstract EjBasePagerHolder<T> onBundHolder(ViewGroup container); public void onDestroy(){ } public void onActivityResult(int requestCode, int resultCode, Intent data) { } protected abstract class EjBasePagerHolder<D>{  /**上下文*/  protected Context mContext;  private int position;  SparseArray<View> sparseArray;  View itemView;  protected EjBasePagerHolder(View itemView){   this.itemView = itemView;   this.mContext = itemView.getContext();   sparseArray = new SparseArray<>();   initView();  }  public abstract void initView();  public View findViewById(int id){   View view = sparseArray.get(id);   if(null == view){    view = itemView.findViewById(id);    sparseArray.append(id,view);   }   return view;  }  public abstract void bindDada(D t,int position);  public void onActivityResult(int requestCode, int resultCode, Intent data) {  }  public void setPosition(int position) {   this.position = position;  }  public int getPosition() {   return position;  }  public void onDestroy(){   sparseArray.clear();  } }}

public class EjMainFmtBannerPagerAdapter extends EjBasePagerAdapter<EjMainFragmentDataBean>{ public EjMainFmtBannerPagerAdapter(List<EjMainFragmentDataBean> list) {  super(list); } @Override protected EjBasePagerHolder<EjMainFragmentDataBean> onBundHolder(ViewGroup container) {  return new EjBasePagerHolder<EjMainFragmentDataBean>(LayoutInflater.from(container.getContext()).inflate(R.layout.ejmain_item_fmt_banner,null)) {   private ImageView ejmain_iv_banner;   @Override   public void initView() {    ejmain_iv_banner = (ImageView)findViewById(R.id.ejmain_iv_banner);   }   @Override   public void bindDada(EjMainFragmentDataBean t, int position) {    GlidUtil.loadUrl(t.img1,ejmain_iv_banner,mContext);   }  }; }}