如何替换被同一进程锁定的文件？

Question

我正在尝试调整图像的大小。首先，我将图像读入字节数组，在内存中调整大小并将其写回同一个文件：

    public static void CropAndResizeImage(EntryImage image, int left, int top, int right, int bottom)
    {
        Size newSize = new Size();
        string imagePathAndFilename = HttpContext.Current.Server.MapPath(image.URL);

        //byte[] photoBytes = File.ReadAllBytes(imagePathAndFilename);
        using (FileStream fs = new FileStream(imagePathAndFilename, FileMode.Open, FileAccess.ReadWrite))
        {
            fs.Position = 0;
            var photoBytes = new byte[fs.Length];
            int read = fs.Read(photoBytes, 0, photoBytes.Length);

            // Process photo and resize
            using (MemoryStream inStream = new MemoryStream(photoBytes))
            using (MemoryStream outStream = new MemoryStream())
            {
                using (ImageFactory imageFactory = new ImageFactory(preserveExifData: true))// Initialize the ImageFactory using the overload to preserve EXIF metadata.
                {

                    ISupportedImageFormat format = new JpegFormat { Quality = 75 }; // Format is automatically detected though can be changed.
                    Size maxSize = new Size(1024, 1024);
                    ResizeLayer layer = new ResizeLayer(maxSize, upscale: false, resizeMode: ResizeMode.Max);
                    layer.Upscale = false;

                    // Load, resize, set the format and quality and save an image.
                    imageFactory.Load(inStream)
                                .Crop(new CropLayer(left, top, right - left, bottom - top, CropMode.Pixels)) // Crop is relative to image edge, not absolute coords.
                                .Resize(layer)
                                .Format(format)
                                .Save(outStream);

                    newSize.Width = imageFactory.Image.Width;
                    newSize.Height = imageFactory.Image.Height;
                }

                // Write back to the same file
                fs.Position = 0;
                fs.SetLength(photoBytes.Length);
                fs.Write(photoBytes, 0, photoBytes.Length);
            }
        }
    }

但是，通常会出现以下错误：

进程无法访问文件：'C：\folder\image.jpg'，因为它正被另一个进程使用。

为什么会这样？我会假设File. ReadAllBytes（）会自动关闭文件？

进程资源管理器中没有显示文件句柄或锁（这似乎很奇怪）。

即使我在while循环中添加了一些延迟，循环也永远不会完成，这意味着文件被永久锁定：

bool saved = false;
while (!saved)
{
    try
    {
        SaveImageToFile(imagePathAndFilename, outStream);
        saved = true;
    }
    catch (IOException ex)
    {
        System.Threading.Thread.Sleep(1000);
    }
}

编辑：更新以显示完整的代码，并将机械师的答案合并到我上面的代码中以显示我的实现。

Answer 1

您可以使用文件流并保留文件，而不是读取所有字节吗？如果此代码不准确，很抱歉，如果文件长度使用fs缩短，您可能需要修剪访问字节。设置长度函数

using (FileStream fs = new FileStream(imagePathAndFilename, FileMode.Open, FileAccess.ReadWrite))   
{
    fs.Position = 0;
    var buffer = new byte[fs.Length];
    int read = fs.Read(buffer, 0, buffer.Length);

    // Manipulate bytes here

    fs.Position = 0;
    fs.SetLength(buffer.Length);
    fs.Write(buffer, 0, buffer.Length);
}

编辑：添加SetLength以更改流大小