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我正在尝试实现一个图像库，它应该显示〜 5-15 个较小的图像和一个“当前选择的”更大的图像。

它看起来像：http ://www.mobisoftinfotech.com/blog/wp-content/uploads/2012/06/galleryDemo.png

我查了很多资源，现在决定使用位图缓存（lru-cache）（感谢这个论坛的人！）。

我目前没有内存泄漏，但我对这个解决方案不满意，因为每次滚动时，都会从缓存中删除一些图像，我必须重新加载它们......所以用户必须等待重新加载图像......每次滚动到另一边时等待 0.5 - 1 秒真的很烦人......

public static WeakReference<Bitmap> getBitmap(String imageName, int width,
        int height) {
    if (!imageName.contains(".jpg")){
        imageName += ".jpg";
    }
    String pathToImage = getPathToImage(imageName);
    Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(pathToImage, options);

    /*
     * Calculate inSampleSize
     */
    options.inSampleSize = calculateInSampleSize(options, width, height);

    /*
     * Removes the alpha-channel from bitmap (not necessary)
     */
    options.inPreferredConfig = Bitmap.Config.RGB_565;

    /*
     * Decode bitmap with inSampleSize set
     */
    options.inJustDecodeBounds = false;

    WeakReference<Bitmap> scaledBitmap = new WeakReference<Bitmap>(
            BitmapFactory.decodeFile(pathToImage, options));
    return scaledBitmap;

我是否有可能在获取图像时出错？目前，我将为单选图像使用 320x480 分辨率，为底部列表使用 64x64 分辨率...

真的很奇怪，不管图像的分辨率有多大，lru-cache 仍然会删除一些图像，即使我只选择 64x64 图像......我可能做错了什么lru缓存？

以下代码显示了我的实现：

    /*
     * Bitmaps which should be shown
     */
    mMemoryCache = (BitmapCache) getLastNonConfigurationInstance();
    if (mMemoryCache == null) {
        // Get max available VM memory, exceeding this amount will throw an
        // OutOfMemory exception. Stored in kilobytes as LruCache takes an
        // int in its constructor.
        final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);

        // Use 1/4th of the available memory for this memory cache.
        final int cacheSize = maxMemory / 2; // TODO default 8

        mMemoryCache = new BitmapCache(cacheSize);
    }

和类位图缓存：

public BitmapCache(int maxSize, Resources resources) {
    super(maxSize);
    this.resources = resources;
}

@Override
protected int sizeOf(String key, AsyncDrawable value) {
    if (value.getBitmap() != null) {
        /* 
         * The cache size will be measured in kilobytes rather than
         * number of items.
         */
        return value.getBitmap().getRowBytes()
                * value.getBitmap().getHeight() / 1024;
    }
    return super.sizeOf(key, value);
}

public void loadBitmap(Picture picture, ImageView mImageView,
        ImageResolution resolution) {
    if (cancelPotentialWork(picture.getFileName(), //  + resolution.name()
            mImageView)) {
        final BitmapWorkerTask task = new BitmapWorkerTask(this,
                mImageView, picture, resolution);
        final AsyncDrawable asyncDrawable = new AsyncDrawable(resources,
                null, task);
        mImageView.setImageDrawable(asyncDrawable);
        task.execute();
    }
}

非常感谢你 ：（

更多代码：BitmapWorkerTask：

@Override
protected Bitmap doInBackground(Void... params) {
    /*
     *  Decode image in background.
     */
    final Bitmap bitmap = FileHandler.getBitmap(
            picture.getPictureId() + "", resolution).get();
    return bitmap;
}

@Override
protected void onPostExecute(Bitmap bitmap) {
    /*
     *  Once complete, see if ImageView is still around and set bitmap.
     */
    if (isCancelled()) {
        bitmap = null;
    }

    if (imageViewReference != null && bitmap != null) {
        final ImageView imageView = imageViewReference.get();

        if (imageView != null) {
            final Drawable drawable = imageView.getDrawable();
            if (drawable instanceof AsyncDrawable) {
                final AsyncDrawable asyncDrawable = (AsyncDrawable) drawable;
                final BitmapWorkerTask bitmapWorkerTask = asyncDrawable
                        .getBitmapWorkerTask();
                if (this == bitmapWorkerTask && imageView != null) {
                    imageView.setImageBitmap(bitmap);
                    bitmapCache.addBitmapToMemoryCache(
                            picture.getFileName(), // + resolution.name()
                            asyncDrawable);
                }
            }
        }
    }
}
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1 回答 1

0

惊人的！我发现了为什么它不能工作的错误。问题出在我的 LruCache 中，它存储了 AsyncDrawables，这完全是愚蠢的。每次调用LruCache中的sizeOf，asyncdrawable里面的bitmap都是null，所以他只返回super.sizeOf(key, value)。

现在它就像一个魅力！:)

感谢您的帮助！

于 2013-02-09T20:50:47.130 回答