C# 从使用DMZ API的公共web API获取文件

我有两个API：

公共API

DMZ中的API

我需要实现一个在公共API中返回文件的方法

DMZ中的API：

    public HttpResponseMessage GetContent(int id)
    {
        var content = from m in db.messagestoimages
                      where m.Message == id
                      select m;

        if (content == null || content.Count() == 0)
        {
            return null;
        }
        string fileName = content.First().ImageURL;

        string fullPath = AppDomain.CurrentDomain.BaseDirectory  + fileName;
        if (File.Exists(fullPath))
        {

            HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
            var fileStream = new FileStream(fullPath, FileMode.Open);
            response.Content = new StreamContent(fileStream);
            response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
            response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");
            response.Content.Headers.ContentDisposition.FileName = fileName;
            return response;
        }

        return null;
    }

公共API

    public HttpResponseMessage Get(string id)
    {
        try
        {
            //if (form.file != null && form.file.Length > 0)
            {
                using (var client = new HttpClient())
                {
                    try
                    {
                        string host = configuration.GetSection("MySettings").GetSection("OctopusURL").Value;

                        client.BaseAddress = new Uri(host);

                        var response =  client.GetAsync("api/Content/" + id);


                        return response.Result;

                    }
                    catch (Exception ex)
                    {
                        return new HttpResponseMessage(HttpStatusCode.NotFound);
                    }
                }
            }

        }
        catch (Exception ex)
        {
            return new HttpResponseMessage(HttpStatusCode.NotFound); // 500 is generic server error
        }
    }

若我直接调用DMZ方法，文件下载成功。 如果我调用公共API，我不会得到一个文件。唯一内容

{
    "version": {
        "major": 1,
        "minor": 1,
        "build": -1,
        "revision": -1,
        "majorRevision": -1,
        "minorRevision": -1
    },
    "content": {
        "headers": [
            {
                "key": "Content-Length",
                "value": [
                    "17488"
                ]
            },
            {
                "key": "Content-Type",
                "value": [
                    "application/octet-stream"
                ]
            },
            {
                "key": "Expires",
                "value": [
                    "-1"
                ]
            },
            {
                "key": "Content-Disposition",
                "value": [
                    "attachment; filename=\"/Userimage/3A297B090A41B649BF80.jpeg\""
                ]
            }
        ]
    },
    "statusCode": 200,
    "reasonPhrase": "OK",
    "headers": [
        {
            "key": "Cache-Control",
            "value": [
                "no-cache"
            ]
        },
        {
            "key": "Pragma",
            "value": [
                "no-cache"
            ]
        },
        {
            "key": "Server",
            "value": [
                "Microsoft-IIS/10.0"
            ]
        },
        {
            "key": "X-AspNet-Version",
            "value": [
                "4.0.30319"
            ]
        },
        {
            "key": "X-SourceFiles",
            "value": [
                "=?UTF-8?B?QzpcVXNlcnNcbmFyaW1cc291cmNlXHJlcG9zXENoYXRBc3Npc3RlbnRcQ2hhdEFzc2lzdGFudFxDaGF0QXNzaXN0ZW50XGFwaVxDb250ZW50XDkzMjQ=?="
            ]
        },
        {
            "key": "X-Powered-By",
            "value": [
                "ASP.NET"
            ]
        },
        {
            "key": "Date",
            "value": [
                "Wed, 21 Aug 2019 13:43:26 GMT"
            ]
        }
    ],
    "requestMessage": {
        "version": {
            "major": 2,
            "minor": 0,
            "build": -1,
            "revision": -1,
            "majorRevision": -1,
            "minorRevision": -1
        },
        "content": null,
        "method": {
            "method": "GET"
        },
        "requestUri": "http://localhost:60236/api/Content/9324",
        "headers": [],
        "properties": {}
    },
    "isSuccessStatusCode": true
}

我怎样才能解决这个问题

我尝试更改公共API，使其获得流、创建响应和返回，但效果不一样

                        string host = configuration.GetSection("MySettings").GetSection("OctopusURL").Value;

                        client.BaseAddress = new Uri(host);

                        var responseFromServer = await client.GetAsync("api/Images/" + id);
                        Stream streamToReadFrom = await responseFromServer.Content.ReadAsStreamAsync();

                        HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
                        response.Content = new StreamContent(streamToReadFrom);
                        response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
                        response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");
                        response.Content.Headers.ContentDisposition.FileName = "sd.jpg";
                        return response;      

---

您应该使用公共API方法获取文件流，然后将其返回给客户端，与DMZ返回文件流的方式相同。

经过测试，工作正常。 第一控制器：

public class TestController : ApiController
{
    [Route("GetContent")]
    public HttpResponseMessage Get()
    {
        string fileName = "a.json";

        string fullPath = AppDomain.CurrentDomain.BaseDirectory + fileName;
        if (File.Exists(fullPath))
        {
            HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
            var fileStream = new FileStream(fullPath, FileMode.Open);
            response.Content = new StreamContent(fileStream);
            response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
            response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");
            response.Content.Headers.ContentDisposition.FileName = fileName;
            return response;
        }

        return null;
    }
}

public class PublicController : ApiController
{
    [Route("GetContent")]
    public async Task<HttpResponseMessage> Get()
    {
        using (var client = new HttpClient())
        {
            try
            {
                client.BaseAddress = new Uri("http://localhost:9000/");

                var responseFromServer = await client.GetAsync("api/Test/GetContent");
                Stream streamToReadFrom = await responseFromServer.Content.ReadAsStreamAsync();

                HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
                response.Content = new StreamContent(streamToReadFrom);
                response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
                response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");
                response.Content.Headers.ContentDisposition.FileName = "sd.json";
                return response;

            }
            catch (Exception ex)
            {
                return new HttpResponseMessage(HttpStatusCode.NotFound);
            }
        }
    }
}

第二控制器：

public class TestController : ApiController
{
    [Route("GetContent")]
    public HttpResponseMessage Get()
    {
        string fileName = "a.json";

        string fullPath = AppDomain.CurrentDomain.BaseDirectory + fileName;
        if (File.Exists(fullPath))
        {
            HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
            var fileStream = new FileStream(fullPath, FileMode.Open);
            response.Content = new StreamContent(fileStream);
            response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
            response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");
            response.Content.Headers.ContentDisposition.FileName = fileName;
            return response;
        }

        return null;
    }
}

public class PublicController : ApiController
{
    [Route("GetContent")]
    public async Task<HttpResponseMessage> Get()
    {
        using (var client = new HttpClient())
        {
            try
            {
                client.BaseAddress = new Uri("http://localhost:9000/");

                var responseFromServer = await client.GetAsync("api/Test/GetContent");
                Stream streamToReadFrom = await responseFromServer.Content.ReadAsStreamAsync();

                HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
                response.Content = new StreamContent(streamToReadFrom);
                response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
                response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");
                response.Content.Headers.ContentDisposition.FileName = "sd.json";
                return response;

            }
            catch (Exception ex)
            {
                return new HttpResponseMessage(HttpStatusCode.NotFound);
            }
        }
    }
}

公共类PublicController:ApiController
{
[路线（“获取内容”）]
公共异步任务Get（）
{
使用（var client=new HttpClient（））
{
尝试
{
client.BaseAddress=新Uri（“http://localhost:9000/");
var responseFromServer=await client.GetAsync（“api/Test/GetContent”）；
streamToReadFrom=await responseFromServer.Content.ReadAsStreamAsync（）；
HttpResponseMessage response=新的HttpResponseMessage（HttpStatusCode.OK）；
response.Content=新的StreamContent（streamToReadFrom）；
response.Content.Headers.ContentType=新的MediaTypeHeaderValue（“应用程序/八位字节流”）；
response.Content.Headers.ContentDisposition=新的ContentDispositionHeaderValue（“附件”）；
response.Content.Headers.ContentDisposition.FileName=“sd.json”；
返回响应；
}
捕获（例外情况除外）
{
返回新的HttpResponseMessage（HttpStatusCode.NotFound）；
}
}
}
}

此对公共控制器方法的调用将下载文件：

---

我试过了。请检查原始帖子，我在最后更新了。相同的结果。您是否尝试更改返回类型，以便可以返回

返回文件（contentStream、content\u type、filename）？我刚刚更改为返回文件（streamToReadFrom，“jpg”，“test”）；它返回InvalidOperationException:无法从返回类型为“Microsoft.AspNetCore.Mvc.FileStreamResult”的操作方法返回null。很抱歉，我将尝试调试它并查看流为null的原因。