C# 没有 MediaTypeFormatter 可用于从媒体类型为“text/plain”的内容中读取“String”类型的对象
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/12512483/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
No MediaTypeFormatter is available to read an object of type 'String' from content with media type 'text/plain'
提问by Renzzs
This is the situation:
情况是这样的：
Their is a external webservice in Servoyand I want to use this service in a ASP.NET MVC applicatie.
他们是Servoy 中的外部 Web服务，我想在 ASP.NET MVC 应用程序中使用此服务。
With this code I attempt to get the data from the service:
使用此代码，我尝试从服务中获取数据：
HttpResponseMessage resp = client.GetAsync("http://localhost:8080/servoy-service/iTechWebService/axws/shop/_authenticate/mp/112818142456/82cf1988197027955a679467c309274c4b").Result;
resp.EnsureSuccessStatusCode();
var foo = resp.Content.ReadAsAsync<string>().Result;
but when I run the application I get the next error:
但是当我运行应用程序时，我收到下一个错误：
No MediaTypeFormatter is available to read an object of type 'String' from content with media type 'text/plain'.
没有 MediaTypeFormatter 可用于从媒体类型为“text/plain”的内容中读取“String”类型的对象。
If I open Fiddler and run the same url, I see the right data but the content-type is text/plain. However I see in Fiddler also the JSON that I want...
如果我打开 Fiddler 并运行相同的 url，我会看到正确的数据，但内容类型是文本/纯文本。但是我在 Fiddler 中也看到了我想要的 JSON ......
Is it possible to solve this at client side or is it the Servoy webservice?
是否有可能在客户端解决这个问题，或者是 Servoy 网络服务？
Update:
Used HttpWebRequest instead of HttpResponseMessage and read the response with StreamReader...
更新：
使用 HttpWebRequest 而不是 HttpResponseMessage 并使用 StreamReader 读取响应...
采纳答案by Maggie Ying
Try using ReadAsStringAsync() instead.
尝试改用 ReadAsStringAsync()。
var foo = resp.Content.ReadAsStringAsync().Result;
The reason why it ReadAsAsync<string>()doesn't work is because ReadAsAsync<>will try to use one of the default MediaTypeFormatter(i.e. JsonMediaTypeFormatter, XmlMediaTypeFormatter, ...) to read the content with content-typeof text/plain. However, none of the default formatter can read the text/plain(they can only read application/json, application/xml, etc).
它ReadAsAsync<string>()不起作用的原因是因为ReadAsAsync<>将尝试使用默认值之一MediaTypeFormatter（即JsonMediaTypeFormatter, XmlMediaTypeFormatter, ...）来读取带有content-typeof的内容text/plain。然而，没有默认格式化可以读取text/plain（他们只能读application/json，application/xml等等）。
By using ReadAsStringAsync(), the content will be read as string regardless of the content-type.
通过使用ReadAsStringAsync()，无论内容类型如何，内容都将被读取为字符串。
回答by t3chb0t
Or you can just create your own MediaTypeFormatter. I use this for text/html. If you add text/plainto it, it'll work for you too:
或者您可以创建自己的MediaTypeFormatter. 我用这个text/html。如果你添加text/plain它，它也会为你工作：
public class TextMediaTypeFormatter : MediaTypeFormatter
{
public TextMediaTypeFormatter()
{
SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/html"));
}
public override Task<object> ReadFromStreamAsync(Type type, Stream readStream, HttpContent content, IFormatterLogger formatterLogger)
{
return ReadFromStreamAsync(type, readStream, content, formatterLogger, CancellationToken.None);
}
public override async Task<object> ReadFromStreamAsync(Type type, Stream readStream, HttpContent content, IFormatterLogger formatterLogger, CancellationToken cancellationToken)
{
using (var streamReader = new StreamReader(readStream))
{
return await streamReader.ReadToEndAsync();
}
}
public override bool CanReadType(Type type)
{
return type == typeof(string);
}
public override bool CanWriteType(Type type)
{
return false;
}
}
Finally you have to assign this to the HttpMethodContext.ResponseFormatterproperty.
最后，您必须将其分配给HttpMethodContext.ResponseFormatter属性。
