我正在开发一个 Android 应用程序。现在我正在将 bbcode 解析为 html 并将其显示在 TextView 中， TextView 位于自定义 ListView 中。我使用 Html.ImageGetter() 来显示从 AsyncTask 下载的图像。

它适用于少量图片。但是如果要求应用程序下载 40-50 张图片，就会创建 40-50 个任务，它就会变得一团糟。每个任务都会打开一个流来下载图像。之后它将字节解码为位图，调整它们的大小，将它们保存到 sdcard 并回收位图。

现在，如果应用同时加载所有这些图像，它会使用大量内存。我设法让它超过了 48 mb。 16 和 48 之间有很大的差距 :(。我搜索了如何解决这个问题。我从谷歌下载了 AsyncTask 代码:

http://google.com/codesearch/p?hl=en&sa=N&cd=2&ct=rc#uX1GffpyOZk/core/java/android/os/AsyncTask.java&q=lang:java%20AsyncTask

并将池大小设置为 3。但这没有帮助。我真的不知道我在哪里失去了 ram。一旦我放入一个大任务队列，我的 ram 就会发疯。收到几张图片后，情况变得更糟。我不认为这是图像，因为在显示任何图像之前我可以达到 30 mb。该应用程序本身，包括 View 、信息和它的服务使用了 13 MB，其余的都在这里泄露。

队列本身是否分配了大量内存？还是 Html.ImageGetter() 以某种方式泄漏了大量内存？有一个更好的方法吗？

我在这里加载图像:

public void LoadImages(String source) {

    myurl = null;
    try {
        myurl = new URL(source);
    } catch (MalformedURLException e) {
        e.printStackTrace();
    }

    new DownloadImageFromPost().execute(myurl);
}

private class DownloadImageFromPost extends AsyncTask<URL, Integer, Bitmap> {

    @Override
    protected Bitmap doInBackground(URL... params) {
        URL url;
        Log.d(TAG, "Starting new image download");
        try {
            url = params[0];
            HttpURLConnection connection = (HttpURLConnection) url
            .openConnection();
            int length = connection.getContentLength();
            InputStream is = (InputStream) url.getContent();
            byte[] imageData = new byte[length];
            int buffersize = (int) Math.ceil(length / (double) 100);
            int downloaded = 0;
            int read;
            while (downloaded < length) {
                if (length < buffersize) {
                    read = is.read(imageData, downloaded, length);
                } else if ((length - downloaded) <= buffersize) {
                    read = is.read(imageData, downloaded, length
                            - downloaded);
                } else {
                    read = is.read(imageData, downloaded, buffersize);
                }
                downloaded += read;
                publishProgress((downloaded * 100) / length);
            }
            Bitmap bitmap = BitmapFactory.decodeByteArray(imageData, 0,
                    length);
            if (bitmap != null) {
                Log.i(TAG, "Bitmap created");
            } else {
                Log.i(TAG, "Bitmap not created");
            }
            is.close();
            return bitmap;

        } catch (MalformedURLException e) {
            Log.e(TAG, "Malformed exception: " + e.toString());

        } catch (IOException e) {
            Log.e(TAG, "IOException: " + e.toString());

        } catch (Exception e) {

        }


    return null;

}

protected void onPostExecute(Bitmap result) {

        String name = Environment.getExternalStorageDirectory() + "/tempthumbs/" + myurl.toString().hashCode() +".jpg";
        String rname = Environment.getExternalStorageDirectory() + "/tempthumbs/" + myurl.toString().hashCode() +"-t.jpg";
        try {
            if (result != null) {
                    hasExternalStoragePublicPicture(name); 
                    ImageManager manager = new ImageManager(context);
                    Bitmap rezised = manager.resizeBitmap(result, 300, 300);
                    saveToSDCard(result, name,  myurl.toString().hashCode() +".jpg");
                    saveToSDCard(rezised, rname, myurl.toString().hashCode() +"-t.jpg");
                    result.recycle();
                    rezised.recycle();

            } else {

            }
        } catch(NullPointerException e) {
        }

    Log.d(TAG, "Sending images loaded announcement");
    Intent i = new Intent(IMAGE_LOADED);
    i.putExtra("image",  name);
    i.putExtra("source", myurl.toString());
    i.putExtra("class", true);
    context.sendBroadcast(i);

}

}


    private boolean hasExternalStoragePublicPicture(String name) {
    File file = new File(name);
    if (file != null) {
        file.delete();
    }

        try {
            file.createNewFile();

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


        }

    return file.exists();
}

public void saveToSDCard(Bitmap bitmap, String name, String nam) {
    boolean mExternalStorageAvailable = false;
    boolean mExternalStorageWriteable = false;
    String state = Environment.getExternalStorageState();
    if (Environment.MEDIA_MOUNTED.equals(state)) {
        mExternalStorageAvailable = mExternalStorageWriteable = true;
        Log.v(TAG, "SD Card is available for read and write "
                + mExternalStorageAvailable + mExternalStorageWriteable);
        saveFile(bitmap, name, nam);
    } else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
        mExternalStorageAvailable = true;
        mExternalStorageWriteable = false;
        Log.v(TAG, "SD Card is available for read "
                + mExternalStorageAvailable);
    } else {
        mExternalStorageAvailable = mExternalStorageWriteable = false;
        Log.v(TAG, "Please insert a SD Card to save your Video "
                + mExternalStorageAvailable + mExternalStorageWriteable);
    }
}

private void saveFile(Bitmap bitmap, String fullname, String nam) {

    ContentValues values = new ContentValues();

    File outputFile = new File(fullname);
    values.put(MediaStore.MediaColumns.DATA, outputFile.toString());
    values.put(MediaStore.MediaColumns.TITLE, nam);
    values.put(MediaStore.MediaColumns.DATE_ADDED, System
            .currentTimeMillis());
    values.put(MediaStore.MediaColumns.MIME_TYPE, "image/jpg");
    Uri uri = context.getContentResolver().insert(
            android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI,

            values);;

    try {
        OutputStream outStream = context.getContentResolver()
                .openOutputStream(uri);
        bitmap.compress(Bitmap.CompressFormat.JPEG, 95, outStream);

        outStream.flush();
        outStream.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    bitmap.recycle();
}

在这里我调用了 Html.ImageGetter()，它在列表 getView 中:

holder.content.setText(Html.fromHtml(
   processor.preparePostText(posts.get(position).post_content),
   new Html.ImageGetter() {

      @Override public Drawable getDrawable(String source) {

         Log.d("Forum Service", "image source: " + source);
         if (imageSources.contains(source)) {
            for (int x = 0; x < imageSources.size(); x++) {
               if (source.equals(imageSources.get(x))) {

                  String tmp = oImages.get(x);
                  tmp = tmp.substring(0, tmp.length() - 4);
                  tmp = tmp + "-t.jpg";
                  Drawable d = Drawable.createFromPath(tmp);
                  try {
                     d.setBounds(0, 0, d.getIntrinsicWidth(),
                        d.getIntrinsicHeight());
                  } catch (NullPointerException e) {

                  }
                  Log.d("Forum Service", "Loaded image froms sdcard");
                  return d;
               }
            }

         } else if (notLoadedImages.contains(source)) {
            Log.d("Forum Service", "Waiting for image");
            return null;
         } else {
            notLoadedImages.add(source);
            LoadAllIcons loader = new LoadAllIcons(context);
            loader.LoadImages(source);
            Log.d("Forum Service", "Asked for image");
            return null;
         }
         return null;
      }

   }, null));

谢谢!

最后的问题是所有任务同时加载。因此，下载时在 ram 中分配了 40 张图像。我设法通过对 AsyncTask 进行以下修改来限制运行任务的数量:

private static final int CORE_POOL_SIZE = 2;
private static final int MAXIMUM_POOL_SIZE = 2;
private static final int KEEP_ALIVE = 1;

private static final BlockingQueue<Runnable> sWorkQueue =
        new LinkedBlockingQueue<Runnable>(100);

最佳答案

马特奥给你答案 http://android-developers.blogspot.com/2010/07/multithreading-for-performance.html

大功告成!

关于android - 管理多个异步任务以从 html 代码下载多个图像，泄漏 ram，有什么想法吗？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/4921011/