android - 内存不足异常 : Load Bunch Of Images From Server

Question

我正在开发一个从服务器 API 下载图像的应用程序...
我们已经创建了一个 API，它提供图像 URL 的 JSON 响应...

我已经创建了用于显示图像的 GridView，它正在成功运行....

但问题是，当图像数量增加时，由于堆内存增加，它会抛出 OutOfMemoryException...

我尝试通过 System.gc(); 手动清除堆内存..但没有效果......

所以，我的问题是:如何从服务器成功加载所有图像而不会出现此问题......我应该做些什么改变来解决这个问题

这是我的 JSON 和代码..

JSON:

{
is_error: "false",
is_error_msg: "Video/Image List",
images: [
     "http://equestsolutions.net/clients/elad/MovieApp/public/uploads/Screenshot_2014-07-21-17-22-43.png",
     "http://equestsolutions.net/clients/elad/MovieApp/public/uploads/IMG_20140521_155703.jpg",
     "http://equestsolutions.net/clients/elad/MovieApp/public/uploads/IMG_20140522_152254.jpg",
     "http://equestsolutions.net/clients/elad/MovieApp/public/uploads/1386231199182.jpg",
     "http://equestsolutions.net/clients/elad/MovieApp/public/uploads/DSC01809.JPG"
],
videos: [ ],
others: [ ]
}

ImageAdapter.java

private class ImageAdapter extends BaseAdapter {

    private final Context mContext;
    ArrayList<String> urls_list;
    ProgressBar pbrLoadImage;

    public ImageAdapter(Context context,ArrayList<String> urls_list) {
        super();
        mContext = context;
        this.urls_list= urls_list;
    }

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

    @Override
    public Object getItem(int position) {
        return urls_list.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup container) {
        ImageView imageView;

        if (convertView == null) { // if it's not recycled, initialize some attributes
            LayoutInflater mInflater = (LayoutInflater)
                    getActivity().getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
            convertView = mInflater.inflate(R.layout.image_grid_fragment_raw, null);
        }
        FrameLayout frm = (FrameLayout)convertView.findViewById(R.id.imageframe);
        pbrLoadImage =(ProgressBar)convertView.findViewById(R.id.pbrLoadImage);
        imageView = (ImageView)convertView.findViewById(R.id.imageFromUrl); ImageView(mContext);
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        imageView.getLayoutParams().height = 160;
        imageView.getLayoutParams().width = 160;

        Log.i("values", "value :"+url_list.get(position));

        new BitmapWorkerTask(imageView).execute(url_list.get(position)); // calling class for download Images...
        return convertView;
    }

    //download Images from path
    class BitmapWorkerTask extends AsyncTask<String, Void, Bitmap> {
        private final WeakReference<ImageView> imageViewReference;
        //private int data = 0;
        String path=null;
        Bitmap mIcon=null;

        public BitmapWorkerTask(ImageView imageView) {
            // Use a WeakReference to ensure the ImageView can be garbage collected
            imageViewReference = new WeakReference<ImageView>(imageView);
        }

        // Decode image in background.
        @Override
        protected Bitmap doInBackground(String... params) {
            //data = params[0];
            path = params[0];

            InputStream in=null;
            ByteArrayOutputStream out=null;
            try {
                in = new java.net.URL(path).openStream();
                mIcon = BitmapFactory.decodeStream(in);
                out= new ByteArrayOutputStream();
                mIcon.compress(Bitmap.CompressFormat.PNG, 100, out);
                in.close();
                out.close();

            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }


            //return decodeSampledBitmapFromResource(getResources(), data, 100, 100));
            //return BitmapFactory.decodeStream(new ByteArrayInputStream(out.toByteArray()));
            return mIcon;
        }

        // Once complete, see if ImageView is still around and set bitmap.
        @Override
        protected void onPostExecute(Bitmap bitmap) {

            if (imageViewReference != null && bitmap != null) {

                final ImageView imageView = imageViewReference.get();

                if (imageView != null) {
                    imageView.setImageBitmap(bitmap);
                }
            }
        }
    }
}

请告诉我应该做哪些改变来解决我的问题..

提前感谢您的帮助...

Answer 1

这是android中一个很常见的问题。将位图加载到内存中可能会导致 OutOfMemoryException。

我建议你使用类似 picasso 的库，这个库在后台为您加载图像，并通过一行代码调整它们的大小以适合您的 ImageView。

Picasso.with(context).load(URL).fit().centerCrop().into(imageView);