以下代码给出OutOfMemoryError，而仅在小米、华硕Zenfone2和三星S5设备上执行压缩方法。
Bitmap bm = BitmapFactory.decodeFile(<sd_card_path_here>);
bm.compress(Bitmap.CompressFormat.JPEG, 20, out);
目标 sd 卡路径有一个用 0 字节创建的文件
非常感谢任何帮助，并在此先感谢。
【问题讨论】：
outOfMemoryError。你想知道你到底在做什么吗？
标签： android bitmap out-of-memory android-imageview
您应该有效地阅读加载位图，以便基本了解您可能遇到 OutOfMemory 异常的原因。 此外，处理位图应该在 UI 线程之外完成，以避免 ANR 错误。
参考： http://developer.android.com/training/displaying-bitmaps/load-bitmap.html#load-bitmap
【讨论】：
位图的宽度/高度是多少？
Android 的 OpenGL 版本限制每个位图为 4096*4096 像素（65 兆字节未压缩图像）
您也可以尝试在 AndroidManifest.xml 中增加应用程序内存
<application ...
android:largeHeap="true"..></application>
如果这没有帮助，您必须按照http://developer.android.com/training/displaying-bitmaps/load-bitmap.html#load-bitmap 中所述缩小图像
【讨论】：
我从这里得到了有效的答案：
public String compressImage(String imageUri) {
String filePath = getRealPathFromURI(imageUri);
Bitmap scaledBitmap = null;
BitmapFactory.Options options = new BitmapFactory.Options();
// by setting this field as true, the actual bitmap pixels are not loaded in the memory. Just the bounds are loaded. If
// you try the use the bitmap here, you will get null.
options.inJustDecodeBounds = true;
Bitmap bmp = BitmapFactory.decodeFile(filePath, options);
int actualHeight = options.outHeight;
int actualWidth = options.outWidth;
// max Height and width values of the compressed image is taken as 816x612
float maxHeight = 816.0f;
float maxWidth = 612.0f;
float imgRatio = actualWidth / actualHeight;
float maxRatio = maxWidth / maxHeight;
// width and height values are set maintaining the aspect ratio of the image
if (actualHeight > maxHeight || actualWidth > maxWidth) {
if (imgRatio < maxRatio) { imgRatio = maxHeight / actualHeight; actualWidth = (int) (imgRatio * actualWidth); actualHeight = (int) maxHeight; } else if (imgRatio > maxRatio) {
imgRatio = maxWidth / actualWidth;
actualHeight = (int) (imgRatio * actualHeight);
actualWidth = (int) maxWidth;
} else {
actualHeight = (int) maxHeight;
actualWidth = (int) maxWidth;
}
}
// setting inSampleSize value allows to load a scaled down version of the original image
options.inSampleSize = calculateInSampleSize(options, actualWidth, actualHeight);
// inJustDecodeBounds set to false to load the actual bitmap
options.inJustDecodeBounds = false;
// this options allow android to claim the bitmap memory if it runs low on memory
options.inPurgeable = true;
options.inInputShareable = true;
options.inTempStorage = new byte[16 * 1024];
try {
// load the bitmap from its path
bmp = BitmapFactory.decodeFile(filePath, options);
} catch (OutOfMemoryError exception) {
exception.printStackTrace();
}
try {
scaledBitmap = Bitmap.createBitmap(actualWidth, actualHeight,Bitmap.Config.ARGB_8888);
} catch (OutOfMemoryError exception) {
exception.printStackTrace();
}
float ratioX = actualWidth / (float) options.outWidth;
float ratioY = actualHeight / (float) options.outHeight;
float middleX = actualWidth / 2.0f;
float middleY = actualHeight / 2.0f;
Matrix scaleMatrix = new Matrix();
scaleMatrix.setScale(ratioX, ratioY, middleX, middleY);
Canvas canvas = new Canvas(scaledBitmap);
canvas.setMatrix(scaleMatrix);
canvas.drawBitmap(bmp, middleX - bmp.getWidth() / 2, middleY - bmp.getHeight() / 2, new Paint(Paint.FILTER_BITMAP_FLAG));
// check the rotation of the image and display it properly
ExifInterface exif;
try {
exif = new ExifInterface(filePath);
int orientation = exif.getAttributeInt(
ExifInterface.TAG_ORIENTATION, 0);
Log.d("EXIF", "Exif: " + orientation);
Matrix matrix = new Matrix();
if (orientation == 6) {
matrix.postRotate(90);
Log.d("EXIF", "Exif: " + orientation);
} else if (orientation == 3) {
matrix.postRotate(180);
Log.d("EXIF", "Exif: " + orientation);
} else if (orientation == 8) {
matrix.postRotate(270);
Log.d("EXIF", "Exif: " + orientation);
}
scaledBitmap = Bitmap.createBitmap(scaledBitmap, 0, 0,
scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix,
true);
} catch (IOException e) {
e.printStackTrace();
}
FileOutputStream out = null;
String filename = getFilename();
try {
out = new FileOutputStream(filename);
// write the compressed bitmap at the destination specified by filename.
scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 80, out);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
return filename;
}
public String getFilename() {
File file = new File(Environment.getExternalStorageDirectory().getPath(), "MyFolder/Images");
if (!file.exists()) {
file.mkdirs();
}
String uriSting = (file.getAbsolutePath() + "/" + System.currentTimeMillis() + ".jpg");
return uriSting;
}
private String getRealPathFromURI(String contentURI) {
Uri contentUri = Uri.parse(contentURI);
Cursor cursor = getContentResolver().query(contentUri, null, null, null, null);
if (cursor == null) {
return contentUri.getPath();
} else {
cursor.moveToFirst();
int index = cursor.getColumnIndex(MediaStore.Images.ImageColumns.DATA);
return cursor.getString(index);
}
}
public int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
final int heightRatio = Math.round((float) height/ (float) reqHeight);
final int widthRatio = Math.round((float) width / (float) reqWidth);
inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio; } final float totalPixels = width * height; final float totalReqPixelsCap = reqWidth * reqHeight * 2; while (totalPixels / (inSampleSize * inSampleSize) > totalReqPixelsCap) {
inSampleSize++;
}
return inSampleSize;
}
参考链接：LINK
【讨论】：