BitmapFactory.decodeFile为同一路径返回null

Question

问题是，即使路径相同，但是当我调用函数时，decodefile函数会返回null。

public static Bitmap lessResolution(String filePath, int width, int height) {
    int reqHeight = width;
    int reqWidth = height;
    BitmapFactory.Options options = new BitmapFactory.Options();

    options.inJustDecodeBounds = true;
    //BitmapFactory.decodeFile(filePath, options);

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

    options.inJustDecodeBounds = false;

    Bitmap b = BitmapFactory.decodeFile(filePath, options);

    Log.d("test1","f:" + filePath);
    Log.d("test1","b:" + b);

    return b;
}

成功案例：

02-10 09:28:23.554 22444-22444/? D/test1: f:/storage/emulated/0/MyApp/1486690065.jpg
02-10 09:28:23.554 22444-22444/? D/test1: b:android.graphics.Bitmap@8756c

失败案例：

02-10 09:29:22.425 22444-22444/? D/test1: f:/storage/emulated/0/MyApp/1486690065.jpg
02-10 09:29:22.425 22444-22444/? D/test1: b:null

非常感谢你的帮助。