加载图像 ListView 时 outOfMemory答案

【问题标题】：outOfMemory when loading images ListView加载图像 ListView 时 outOfMemory
【发布时间】：2014-04-03 18:14:24
【问题描述】：

我从互联网上下载照片。在同一页面上有一个网站，其中有 18 张照片（80x60 px ~ 10kb）。

所以我做了一个加载新图片的列表（sleduyuschuyuyu页面）问题是当我加载三个或更多页面时，发生内存错误问题是如何摆脱？

现在我构建一个位图数组

for (Element titles : title) {
                    if (titles.children().hasClass("btl")){
                    m = new HashMap<String, Object>();
                    m.put(MyActivity.ATTRIBUTE_NAME_TEXT, titles.select("a[href]").attr("abs:href"));
                    Picasso p = Picasso.with(MyActivity.context);
                    m.put(MyActivity.ATTRIBUTE_NAME_PHOTO,Bitmap.createScaledBitmap(p.load(titles.select("img").attr("abs:src")).get(),80,60, true) );
                    data.add(m);
                    }
                }

在适配器中

@Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        final Map<String, Object> itemData = datas.get(position*2);

        final Map<String, Object> itemData2 = datas.get(position*2+1);
        Bitmap bitmap2 = null;
        Bitmap bitmap = (Bitmap) itemData.get("img");
        if(itemData2!=null)
            bitmap2 = (Bitmap) itemData2.get("img");

        View rowView = convertView;
        if (rowView == null) {
            LayoutInflater inflater = context.getLayoutInflater();
            rowView = inflater.inflate(R.layout.items, null, true);
            holder = new ViewHolder();
            holder.ivImage = (ImageView) rowView.findViewById(R.id.imageView);
            holder.ivImage2 = (ImageView) rowView.findViewById(R.id.imageView1);
            rowView.setTag(holder);
        } else {
            holder = (ViewHolder) rowView.getTag();
        }
        holder.ivImage.setImageBitmap(bitmap);
        holder.ivImage2.setImageBitmap(bitmap2);
        holder.ivImage.setTag(position*2);
        holder.ivImage2.setTag(position*2+1);
        holder.ivImage.setOnClickListener(this);
        holder.ivImage2.setOnClickListener(this);
        return rowView;
    }

有人建议我将图像保存在缓存中并从那里加载它们，但不知道该怎么做。

请帮忙

【问题讨论】：

标签： android out-of-memory

【解决方案1】：

使用磁盘缓存...这篇文章还有很多其他有用的加载位图的技巧 http://developer.android.com/training/displaying-bitmaps/cache-bitmap.html#disk-cache

【讨论】：

【解决方案2】：

加载图像的最佳方式是http://square.github.io/picasso/的毕加索库

【讨论】：

【解决方案3】：

您将通过将图像解码为所需大小来读取图像....

把图片转换成这样的方法.... 它用于可绘制资源....

Bitmap bmap2 = decodeSampledBitmapFromResource(getResources(),
     R.drawable.hydrangeas, width, height);  


public static Bitmap decodeSampledBitmapFromResource(Resources res,
            int resId, int reqWidth, int reqHeight) {

        // First decode with inJustDecodeBounds=true to check dimensions
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeResource(res, resId, options);

        // Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, reqWidth,
                reqHeight);

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        return BitmapFactory.decodeResource(res, resId, options);
    }

    public static int calculateInSampleSize(BitmapFactory.Options options,
            int reqWidth, int reqHeight) {
        // Raw height and width of image
        final int height = options.outHeight;
        final int width = options.outWidth;
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {

            final int halfHeight = height / 2;
            final int halfWidth = width / 2;

            // Calculate the largest inSampleSize value that is a power of 2 and
            // keeps both
            // height and width larger than the requested height and width.
            while ((halfHeight / inSampleSize) > reqHeight
                    && (halfWidth / inSampleSize) > reqWidth) {
                inSampleSize *= 2;
            }
        }

        return inSampleSize;
    }

以下哪种方法使用流进行解码......

public static Bitmap decodeSampledBitmapFromResource(InputStream in,
        int reqWidth, int reqHeight) throws IOException {

    // First decode with inJustDecodeBounds=true to check dimensions
    final BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    in.mark(in.available());
    BitmapFactory.decodeStream(in, null, options);
    // Calculate inSampleSize
    options.inSampleSize = calculateInSampleSize(options, reqWidth,
            reqHeight);
    in.reset();
    // Decode bitmap with inSampleSize set
    options.inJustDecodeBounds = false;
    return BitmapFactory.decodeStream(in, null, options);
}

假设你将在 all 方法中失败你将尝试这个逻辑，你只需将这一行添加到你的 mainfest 文件中......

您只需将此行添加到清单文件中。它将为您的应用程序分配大内存。

    android:largeHeap="true"

【讨论】：