图片缓存加载方法

public class MyVideoThumbLoader {
    private ImageView imgView;
    private String path;
    //创建cache
    private LruCache<String, Bitmap> lruCache;

    public MyVideoThumbLoader() {
        int maxMemory = (int) Runtime.getRuntime().maxMemory();//获取最大的运行内存
        int maxSize = maxMemory / 4;//拿到缓存的内存大小
        lruCache = new LruCache<String, Bitmap>(maxSize) {
            @Override
            protected int sizeOf(String key, Bitmap value) {
                //这个方法会在每次存入缓存的时候调用
                return value.getByteCount();
            }
        };
    }

    public void addVideoThumbToCache(String path, Bitmap bitmap) {
        if (getVideoThumbToCache(path) == null) {
            //当前地址没有缓存时，就添加
            lruCache.put(path, bitmap);
        }
    }

    public Bitmap getVideoThumbToCache(String path) {

        return lruCache.get(path);

    }

    public void showThumbByAsyncTask(String path, ImageView imgView) {

        if (getVideoThumbToCache(path) == null) {
            //异步加载
            imgView.setImageResource(R.drawable.video);  //设置默认图片
            new MyAsyncTask(imgView, path).execute(path);
        } else {
            imgView.setImageBitmap(getVideoThumbToCache(path));
        }
    }

    class MyAsyncTask extends AsyncTask<String, Void, Bitmap> {
        private ImageView imgView;
        private String path;

        public MyAsyncTask(ImageView imageView, String path) {
            this.imgView = imageView;
            this.path = path;
        }

        @Override
        protected Bitmap doInBackground(String... params) {
            //通过 android中提供的 ThumbnailUtils.createVideoThumbnail(vidioPath, kind);
            Bitmap bitmap = ThumbnailUtils.extractThumbnail(ThumbnailUtils.createVideoThumbnail(params[0], MediaStore.Images.Thumbnails.MICRO_KIND), 100, 100); //加入缓存中
            Log.v("getVideoThumbToCache:", "path:" + path);
            // Bitmap bitmap = ThumbnailUtils.createVideoThumbnail(params[0], MediaStore.Video.Thumbnails.MICRO_KIND);
            if (bitmap != null) {
                if (getVideoThumbToCache(params[0]) == null) {
                    addVideoThumbToCache(path, bitmap);
                }
            }
            return bitmap;
        }

        @Override
        protected void onPostExecute(Bitmap bitmap) {

            if (imgView.getTag().equals(path)) {//通过 Tag可以绑定 图片地址和 imageView，这是解决Listview加载图片错位的解决办法之一
                if (bitmap == null) {
                    imgView.setImageResource(R.drawable.video);
                } else {
                    imgView.setImageBitmap(bitmap);
                }
            }
        }
    }
}