WebApi：將MediaTypeFormatter附加到控制器

Question

我想從我的項目中的全局格式化程序中刪除XmlFormatter。我這樣做吧：

var formatters = GlobalConfiguration.Configuration.Formatters; 
formatters.Remove(formatters.XmlFormatter) 

但在同一時間，我想有一個控制器，它能夠返回xml數據類型。是否有可能裝飾我的控制器具有特定屬性或以某種方式將XmlFormatter專門附加到此控制器？

Answer 1

您需要創建一個自定義System.Net.Http.Formatting.IContentNegotiator類，並將所選格式器檢入Negotiate方法中。

public class ApplicationContentNegotiator : IContentNegotiator 
{ 
    private readonly JsonMediaTypeFormatter _jsonFormatter; 
    private readonly MediaTypeHeaderValue _jsonMediaType; 

    private readonly XmlMediaTypeFormatter _xmlFormatter; 
    private readonly MediaTypeHeaderValue _xmlMediaType; 

    public static IContentNegotiator Create() 
    { 
     return new ApplicationContentNegotiator(); 
    } 

    private ApplicationContentNegotiator() 
    { 
     _jsonFormatter = new JsonMediaTypeFormatter(); 
     _jsonMediaType = MediaTypeHeaderValue.Parse("application/json"); 

     _xmlFormatter = new XmlMediaTypeFormatter(); 
     _xmlMediaType = MediaTypeHeaderValue.Parse("application/xml"); 
    } 

    public ContentNegotiationResult Negotiate(Type type, HttpRequestMessage request, IEnumerable<MediaTypeFormatter> formatters) 
    { 
     var controller = new DefaultHttpControllerSelector(request.GetConfiguration()).SelectController(request); 
     if (controller.ControllerName == "MyController") 
      return new ContentNegotiationResult(_xmlFormatter, _xmlMediaType); 

     return new ContentNegotiationResult(_jsonFormatter, _jsonMediaType); 
    } 
} 

然後更換您IContentNegotiator實施服務爲HttpConfiguration對象

GlobalConfiguration.Configuration.Services.Replace(typeof(IContentNegotiator), ApplicationContentNegotiator.Create());