Android利用ViewPager实现图片浏览，解决内存问题

在Android开发中，我们经常遇到利用Viewpager实现图片浏览的需求，这个很好实现，也没什么技术难点，但是最近我在实现这个功能的时候，遇到了一些问题，当图片数量稍微多点时，一直滑动浏览，会导致内存占用一路走高，最终导致oom，在分析了只有，发现是因为viewpager中给的ImageIView一直在新建导致的内存溢出，最后找到了解决方法，让view实现复用，解决了内存问题，代码也比较简单，复写viewdaptaer的instantiateItem()方法,代码如下

public class CarImagesBrowseAdapter extends PagerAdapter {    private ArrayList<String> mDatas;//数据源    private LinkedList<View> mViewCache;//缓存view    private Context mContext;    private int mChildCount;    public CarImagesBrowseAdapter(Context context, ArrayList<String> arrayList) {        this.mContext = context;        this.mDatas = arrayList;        mViewCache = new LinkedList<>();    }    @Override    public void notifyDataSetChanged() {        mChildCount = getCount();        super.notifyDataSetChanged();    }    @Override    public int getCount() {        return this.mDatas.size();    }    @Override    public boolean isViewFromObject(View view, Object object) {        return view == object;    }    @Override    public int getItemPosition(Object object) {        if (mChildCount > 0) {            mChildCount--;            return POSITION_NONE;        }        return super.getItemPosition(object);    }    @Override    public Object instantiateItem(ViewGroup container, int position) {        View convertView = null;        if (mViewCache.size() == 0) {            PhotoDraweeView draweeView = new PhotoDraweeView(mContext);            draweeView.setBackgroundColor(0xff000000);            convertView = draweeView;        } else {            convertView = mViewCache.removeFirst();        }

         //这里我是用Facebook的Fresco加载的图片，你可以在这里换成你使用的图片加载方式        final PhotoDraweeView view = (PhotoDraweeView) convertView;        PipelineDraweeControllerBuilder controller = Fresco.newDraweeControllerBuilder();        controller.setUri(Uri.parse(Constants.PICTURE_HOST + mDatas.get(position)));        controller.setOldController(view.getController());        controller.setControllerListener(new BaseControllerListener<ImageInfo>() {            @Override            public void onFinalImageSet(String id, ImageInfo imageInfo, Animatable animatable) {                super.onFinalImageSet(id, imageInfo, animatable);                if (imageInfo == null) {                    return;                }                view.update(imageInfo.getWidth(), imageInfo.getHeight());            }        });        view.setController(controller.build());        container.addView(convertView, ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);        return convertView;    }    @Override    public void destroyItem(ViewGroup container, int position, Object object) {        View contentView = (View) object;        container.removeView(contentView);        this.mViewCache.add(contentView);    }}

代码也比较简单，相信大家也都能看懂！