读取图像，将其转换为byte[]，然后返回具有内容类型的File()。

public ActionResult ImageResult(Image image, ImageFormat format, string contentType) {
  using (var stream = new MemoryStream())
    {
      image.Save(stream, format);
      return File(stream.ToArray(), contentType);
    }
  }
}

以下是用法:

using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using Microsoft.AspNetCore.Mvc;

从Core 3.2下的字节[]，你可以使用:

public ActionResult Img(int? id) {
    MemoryStream ms = new MemoryStream(GetBytes(id));
    return new FileStreamResult(ms, "image/png");
}

稍微解释一下迪兰的回应:

有三个类实现了FileResult类:

System.Web.Mvc.FileResult
      System.Web.Mvc.FileContentResult
      System.Web.Mvc.FilePathResult
      System.Web.Mvc.FileStreamResult

它们都是不言自明的:

For file path downloads where the file exists on disk, use FilePathResult - this is the easiest way and avoids you having to use Streams. For byte[] arrays (akin to Response.BinaryWrite), use FileContentResult. For byte[] arrays where you want the file to download (content-disposition: attachment), use FileStreamResult in a similar way to below, but with a MemoryStream and using GetBuffer(). For Streams use FileStreamResult. It's called a FileStreamResult but it takes a Stream so I'd guess it works with a MemoryStream.

下面是一个使用内容处理技术的例子(未测试):

    [AcceptVerbs(HttpVerbs.Post)]
    public ActionResult GetFile()
    {
        // No need to dispose the stream, MVC does it for you
        string path = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "App_Data", "myimage.png");
        FileStream stream = new FileStream(path, FileMode.Open);
        FileStreamResult result = new FileStreamResult(stream, "image/png");
        result.FileDownloadName = "image.png";
        return result;
    }

更新:有比我原来的答案更好的选择。这在MVC之外工作得很好，但最好坚持使用返回图像内容的内置方法。见赞成投票的答案。

你当然可以。试试下面这些步骤:

将映像从磁盘加载到字节数组中 缓存图像，如果您希望对图像有更多的请求，并且不需要磁盘I/O(我的示例在下面没有缓存它) 通过响应改变mime类型。ContentType 响应。写出图像字节数组

下面是一些示例代码:

string pathToFile = @"C:\Documents and Settings\some_path.jpg";
byte[] imageData = File.ReadAllBytes(pathToFile);
Response.ContentType = "image/jpg";
Response.BinaryWrite(imageData);

希望有帮助!

如果你想在返回之前修改图像，这可能会有帮助:

public ActionResult GetModifiedImage()
{
    Image image = Image.FromFile(Path.Combine(Server.MapPath("/Content/images"), "image.png"));

    using (Graphics g = Graphics.FromImage(image))
    {
        // do something with the Graphics (eg. write "Hello World!")
        string text = "Hello World!";

        // Create font and brush.
        Font drawFont = new Font("Arial", 10);
        SolidBrush drawBrush = new SolidBrush(Color.Black);

        // Create point for upper-left corner of drawing.
        PointF stringPoint = new PointF(0, 0);

        g.DrawString(text, drawFont, drawBrush, stringPoint);
    }

    MemoryStream ms = new MemoryStream();

    image.Save(ms, System.Drawing.Imaging.ImageFormat.Png);

    return File(ms.ToArray(), "image/png");
}

是的，你可以返回图像

public ActionResult GetImage(string imageFileName)
{
    var path = Path.Combine(Server.MapPath("/Images"), imageFileName + ".jpg"); 
    return base.File(path, "image/jpeg");
}

(请不要忘记将此标记为答案)