Return jpeg image from Asp.Net Core WebAPI

问题

Using asp.net core web api, I want to have my controller action method to return an jpeg image stream.
In my current implementation, browser displays only a json string. My expectation is to see the image in the browser.

While debugging using chrome developer tools I found that the content type is still

Content-Type:application/json; charset=utf-8

returned in the response header, even though in my code I manually set the content type to "image/jpeg".

Looking for a solution My Web API is as below

[HttpGet]
public async Task<HttpResponseMessage> Get()
{
    var image = System.IO.File.OpenRead("C:\\test\random_image.jpeg");
    var stream = new MemoryStream();

    image.CopyTo(stream);
    stream.Position = 0;            
    result.Content = new StreamContent(image);
    result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");
    result.Content.Headers.ContentDisposition.FileName = "random_image.jpeg";
    result.Content.Headers.ContentType = new MediaTypeHeaderValue("image/jpeg");
    result.Content.Headers.ContentLength = stream.Length;

    return result;
}

回答1:

Clean solution use FilestreamResult !!

[HttpGet]
public async Task<IActionResult> Get()
{
    var image = System.IO.File.OpenRead("C:\\test\\random_image.jpeg");
    return File(image, "image/jpeg");
}

Explanation:

In ASP.NET Core you have to use the built-in File() method inside the Controller. This will allow you to manually set the content type.

Don't create and return HttpResponseMessage, like you were used to using in ASP.NET Web API 2. It doesn't do anything, not even throwing errors!!

回答2:

PhysicalFile helps to return file from Asp.Net Core WebAPI with a syntax simple

    [HttpGet]
    public IActionResult Get(int imageId)
    {            
       return PhysicalFile(@"C:\test.jpg", "image/jpeg");
    }

回答3:

In my case, I was using a relative path to the image, so the following was my working solution

[HttpGet]
public async Task<IActionResult> Get()
{
    var url = "/content/image.png";
    var path = GetPhysicalPathFromURelativeUrl(url);
    return PhysicalFile(image, "image/png");
}
public string GetPhysicalPathFromRelativeUrl(string url)
{            
    var path = Path.Combine(_host.Value.WebRootPath, url.TrimStart('/').Replace("/", "\\"));
    return path;
}

回答4:

[HttpGet("Image/{id}")]
    public IActionResult Image(int id)
    {
        if(id == null){ return NotFound(); }
        else{

            byte[] imagen = "@C:\\test\random_image.jpeg";
            return File(imagen, "image/jpeg");
        }
    }

来源：https://stackoverflow.com/questions/40794275/return-jpeg-image-from-asp-net-core-webapi