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我正在开发一个应用程序，该应用程序需要从 android 设备的内置图片库中获取随机图片，然后将其显示在屏幕上。这是我必须使用的：

- 一个名为图片的 ImageView 对象 - 我要显示的图片的 ID、TITLE、DATA、MIME_TYPE 和 SIZE

我认为问题是我不知道我需要在这一行中输入什么信息：

picture.setImageResource(???);

这是我的所有代码，可让您了解我正在尝试做的事情：

public void generateImage() {
    // Get list of images accessible by cursor
    ContentResolver cr = getActivity().getContentResolver();
    String[] columns = new String[] {
                    ImageColumns._ID,
                    ImageColumns.TITLE,
                    ImageColumns.DATA,
                    ImageColumns.MIME_TYPE,
                    ImageColumns.SIZE };
    Cursor cursor = cr.query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
                    columns, null, null, null);

    // Collect Picture IDs
    cursor.moveToFirst();
    ArrayList<Integer> picList = new ArrayList<Integer>();
    while (!cursor.isAfterLast()) {
        picList.add(cursor.getInt(0));
        cursor.moveToNext();
    }// end for

    // Generate random number
    int imageCount = picList.size() - 1;
    Log.d("NUMBER OF IMAGES", "Image Count = " + imageCount);
    Random random = new Random();
    int randomInt = random.nextInt(imageCount);


    // Extract the image
    int picID = picList.get(randomInt);
    picture.setImageResource(picID);

}// end Generate Image

任何人都知道我需要做什么才能将图片对象设置为我从图库中获得的图片（最好使用我已经获得的信息）？

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2 回答 2

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Looks like you are saving an array of the cursor position... that would probably not give you much to work with. I think you'd rather populate an ArrayList with ImageColumns._ID and then use that string as a URI to open the image.

于 2013-03-22T00:31:38.213 回答
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//Extracting the image
columnIndex = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToPosition(randomInt);
filePath = cursor.getString(columnIndex);
imageView.setImageBitmap(decodeSampledBitmapFromResource(filePath,width,height));

为了有效地使用位图，这样您就不会遇到 OutOfMemory 异常，这里有两个来自 androids 开发者页面的函数 [链接 http://developer.android.com/training/displaying-bitmaps/load-bitmap.html ]

public Bitmap decodeSampledBitmapFromResource(String path, int reqWidth, int reqHeight) {

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

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

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        return BitmapFactory.decodeFile(path, 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) {

        // Calculate ratios of height and width to requested height and width
        final int heightRatio = Math.round((float) height / (float) reqHeight);
        final int widthRatio = Math.round((float) width / (float) reqWidth);

        // Choose the smallest ratio as inSampleSize value, this will guarantee
        // a final image with both dimensions larger than or equal to the
        // requested height and width.
        inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
    }

    return inSampleSize;
}
于 2013-05-02T10:41:04.033 回答