gistfile1.java

public class SearchAppAdapter extends PagerAdapter{
  public static final int DEFAULT_MAX_ITEM_SIZE = 4;
	/**
	 * 全部数据集
	 */
	private List<AppInfo> data;
	private Context mContext;
	private int mMaxItemSize = DEFAULT_MAX_ITEM_SIZE;
	/**
	 * 页面数据集
	 */
	private List<List<AppInfo>> pageData;
	private SparseArray<WeakReference<View>> mViewCache;
	
	public SearchAppAdapter(Context context, List<AppInfo> data){
		mContext = context;
		this.data = data;
		pageData = new ArrayList<List<AppInfo>>();
		mViewCache = new SparseArray<WeakReference<View>>();
		fillPageData();
	}
	
	private void fillPageData(){
		List<AppInfo> page = null;
		for (int i = 0; i < data.size(); i ++){
			if (i % mMaxItemSize == 0){
				page = new ArrayList<AppInfo>(mMaxItemSize);
			}
			if (page != null)
				page.add(data.get(i));
			
			if (i % mMaxItemSize == mMaxItemSize -1 || i == data.size() - 1){
				pageData.add(page);
			}
		}
	}

	@Override
	public int getCount() {
		// TODO Auto-generated method stub
		return pageData.size();
	}

	@Override
	public boolean isViewFromObject(View view, Object object) {
		// TODO Auto-generated method stub
		return view == object;
	}

	@Override
	public void destroyItem(ViewGroup container, int position, Object object) {
		// TODO Auto-generated method stub
		if (object instanceof GridView){
			container.removeView((View) object);
			// System.out.println("remove");
		}
	}

	@Override
	public Object instantiateItem(ViewGroup container, int position) {
		// TODO Auto-generated method stub
		//return super.instantiateItem(container, position);
		// System.out.println("add----" + position);
		WeakReference<View> vr = mViewCache.get(position);
		if (vr != null){
			View v = vr.get();
			if (v != null){
				container.addView(v);
				return v;
			}
			mViewCache.remove(position);
		}
		GridView grid = new OneRowGridView(mContext);
		grid.setStretchMode(GridView.STRETCH_COLUMN_WIDTH);
		grid.setNumColumns(mMaxItemSize);
		grid.setLayoutParams(new ViewGroup.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
		grid.setHorizontalSpacing(6);
		grid.setCacheColorHint(Color.TRANSPARENT);
		grid.setSelector(R.drawable.bg_transparent);
		GridAppAdapter adapter = new GridAppAdapter(mContext, pageData.get(position));
		grid.setAdapter(adapter);
		grid.setOnItemClickListener(new SimpleAppItemClickListener(mContext, adapter));
		container.addView(grid);
		mViewCache.put(position, new WeakReference<View>(grid));
		return grid;
	}

	@Override
	public void notifyDataSetChanged() {
		// TODO Auto-generated method stub
		mViewCache.clear();
		super.notifyDataSetChanged();
	}
	
}