Android：BitmapFactory.decodeStream（）

Question

我的应用在源代码的以下行中遇到OOM错误：

image = BitmapFactory.decodeStream(assetManager.open(imgFilename));

在导致应用因OOM错误而被终止的分配之前：

(...)

08-05 21:22:12.443: I/dalvikvm-heap(2319): Clamp target GC heap from 25.056MB to 24.000MB

08-05 21:22:12.443: D/dalvikvm(2319): GC_FOR_MALLOC freed <1K, 50% free 2709K/5379K, external 18296K/19336K, paused 58ms

08-05 21:22:14.513: D/dalvikvm(2319): GC_EXTERNAL_ALLOC freed <1K, 50% free 2709K/5379K, external 18296K/19336K, paused 101ms

08-05 21:22:14.903: I/dalvikvm-heap(2319): Clamp target GC heap from 25.073MB to 24.000MB

08-05 21:22:14.903: D/dalvikvm(2319): GC_FOR_MALLOC freed 0K, 50% free 2709K/5379K, external 18312K/19336K, paused 53ms

08-05 21:22:22.843: D/ddm-heap(2319): Heap GC request

08-05 21:22:22.963: I/dalvikvm-heap(2319): Clamp target GC heap from 25.073MB to 24.000MB

08-05 21:22:22.963: D/dalvikvm(2319): threadid=1: still suspended after undo (sc=1 dc=1)

08-05 21:22:22.963: D/dalvikvm(2319): GC_EXPLICIT freed 1K, 50% free 2710K/5379K, external 18312K/19336K, paused 116ms

DDMS报告有关堆状态的类似图片：

Heap Size:  5.254 MB

Allocated:  2.647 MB

Free:   2.607 MB

%Used:  50.38%

#Objects    49,028  

单步越过此行会导致OOM错误：

08-05 21:26:04.783: D/dalvikvm(2319): GC_EXTERNAL_ALLOC freed <1K, 50% free 2710K/5379K, external 18312K/19336K, paused 57ms

08-05 21:26:05.023: E/dalvikvm-heap(2319): 2097152-byte external allocation too large for this process.

08-05 21:26:05.163: I/dalvikvm-heap(2319): Clamp target GC heap from 25.073MB to 24.000MB

08-05 21:26:05.163: E/GraphicsJNI(2319): VM won't let us allocate 2097152 bytes

08-05 21:26:05.163: D/dalvikvm(2319): GC_FOR_MALLOC freed 0K, 50% free 2710K/5379K, external 18312K/19336K, paused 30ms

08-05 21:26:05.283: D/skia(2319): --- decoder->decode returned false

在Windows上，“ imgFileName”引用的文件的大小据报告为<400K。那么，为什么BitmapFactory.decodeStream尝试分配2MB？

当似乎有足够的可用空间时，为什么会出现OOM错误？

这个应用程式的目标是Android 2.2以上版本。

提前致谢！