ASP.NET WebAPI 03 返回結果

在WebAPI中HttResponseMessage作為消息返回，而在ApiController中我們經常講四類數據作為返回值，void,object(可序列化),IHttpActionResult,HttpResponseMessage,

Void與object

Void:返回狀態碼200,無數據

Object: 返回狀態碼200,數據

 

IHttpActionResult

 

    public interface IHttpActionResult
    {

        Task<System.Net.Http.HttpResponseMessage> ExecuteAsync(CancellationToken cancellationToken);
    }
}

　　

WebAPI為我們定義了一IHttpActionResult接口，從命名我們就可以來它是作為Action執行的返回結果。

 

 

 

 

在WebAPI總已經定義了很多實現了IHttpActionResult的類：

 

這些類大致可以分為：只有狀態碼，重定向，實體序列化，錯誤信息，201Created等幾類。

 

 

狀態碼

CodeStatusResult：指定狀態碼

BadRequestResult：400

OkResult：200

NotFoundResult：404

UnAuthorizedResult：401

ConflictResult：409

InternalServerErrorResult：500

 

重定向

狀態碼302，並返回重定向url

RedirectResult：按絕對路徑

RedirectToRouteResult：按路由

WebApi為我們提供了一個UrlHelp類，可實現路由向絕對路徑的轉換

 

            IDictionary<string, object> route = new Dictionary<string, object>();
            UrlHelper helper = new UrlHelper(Request);
            route["controller"] = "Figure";
            route["action"] = "GetAll";
            string AbsoluteUrl = helper.Link("DefaultApi", route);

　　

實體序列化

FormattedContentResult<T>：自定義序列化方式與狀態碼

NegotiatedContentResult<T>：自定義狀態碼，根據請求頭信息匹配序列化類型

OkNegotiatedContentResult<T>：狀態碼200，根據請求頭信息匹配序列化類型

JsonResult<T>：狀態碼200,Json序列化

 

錯誤信息

ExceptionResult：500, eg: {"Message":"出現錯誤。","ExceptionMessage":"未實現該方法或操作。","ExceptionType":"System.NotImplementedException","StackTrace":null}

BadRequestErrorMessageResult：400，eg: {"Message":"Error"}

InvalidModelStateResult：400，Model綁定錯誤,eg: {"Message":"請求無效。","ModelState":{"argument":["值不在預期的范圍內。"],"implemented":["未實現該方法或操作。"]}}

這三種類型最終都是裝換成HttpError

 

201 Created

CreatedNegotiatedContentResult<T>與CreatedAtRouteNegotiatedContentResult<T>

返回"201 Created"的狀態。

 

同時ApiController也為我們定義許多返回IHttpActionResult的方法

 

    public abstract class ApiController
    {
       
        protected internal virtual InvalidModelStateResult BadRequest(ModelStateDictionary modelState);
 
        protected internal virtual NegotiatedContentResult<T> Content<T>(HttpStatusCode statusCode, T value);
    
        protected internal FormattedContentResult<T> Content<T>(HttpStatusCode statusCode, T value, MediaTypeFormatter formatter);
     
        protected internal virtual FormattedContentResult<T> Content<T>(HttpStatusCode statusCode, T value, MediaTypeFormatter formatter, MediaTypeHeaderValue mediaType);
     
        protected internal FormattedContentResult<T> Content<T>(HttpStatusCode statusCode, T value, MediaTypeFormatter formatter, string mediaType);
     
        protected internal CreatedNegotiatedContentResult<T> Created<T>(string location, T content);
     
        protected internal virtual CreatedNegotiatedContentResult<T> Created<T>(Uri location, T content);
    
        protected internal virtual CreatedAtRouteNegotiatedContentResult<T> CreatedAtRoute<T>(string routeName, IDictionary<string, object> routeValues, T content);
    
        protected internal CreatedAtRouteNegotiatedContentResult<T> CreatedAtRoute<T>(string routeName, object routeValues, T content);

    
        protected internal virtual InternalServerErrorResult InternalServerError();
    
        protected internal virtual ExceptionResult InternalServerError(Exception exception);
    
        protected internal JsonResult<T> Json<T>(T content);
 
        protected internal JsonResult<T> Json<T>(T content, JsonSerializerSettings serializerSettings);
   
        protected internal virtual JsonResult<T> Json<T>(T content, JsonSerializerSettings serializerSettings, Encoding encoding);
     
        protected internal virtual NotFoundResult NotFound();
    
        protected internal virtual OkResult Ok();
   
        protected internal virtual OkNegotiatedContentResult<T> Ok<T>(T content);
    
        protected internal virtual RedirectResult Redirect(string location);

        protected internal virtual RedirectResult Redirect(Uri location);
    
        protected internal virtual RedirectToRouteResult RedirectToRoute(string routeName, IDictionary<string, object> routeValues);
   
        protected internal RedirectToRouteResult RedirectToRoute(string routeName, object routeValues);
     
        protected internal virtual ResponseMessageResult ResponseMessage(HttpResponseMessage response);
      
        protected internal virtual StatusCodeResult StatusCode(HttpStatusCode status);
     
        protected internal virtual UnauthorizedResult Unauthorized(IEnumerable<AuthenticationHeaderValue> challenges);
     
        protected internal UnauthorizedResult Unauthorized(params AuthenticationHeaderValue[] challenges);
       
    }

HttpResponseMessage

HttpResponseMessage表示包括狀態代碼和數HTTP 響應消息。在整個WebAPI中HttpResponseMessage是作為最終的請求結果，自然HttpResponseMessag可以作為Action的返回結果。如果單從返回數據上看我們可以只關心狀態碼（StatusCode），內容(Content)，頭信息（Headers）。

 

 

    public class HttpResponseMessage : IDisposable
    {
        public HttpResponseMessage();
        public HttpResponseMessage(HttpStatusCode statusCode);

        public HttpContent Content { get; set; }
        public HttpResponseHeaders Headers { get; }
        public HttpStatusCode StatusCode { get; set; }
   

    }

　　

其實WebAPI定義了一個ResponseMessageResult,這個類實現了IHttpActionResult接口，這個類只重載了一個構造函數，定義了一個HttpResponseResult的屬性

    public class ResponseMessageResult : IHttpActionResult
    {

        public ResponseMessageResult(HttpResponseMessage response);


        public HttpResponseMessage Response { get; }

        public virtual Task<HttpResponseMessage> ExecuteAsync(CancellationToken cancellationToken);
    }

　　

 

 

 

 

其中WebAPI為我們定義很多HttpContent的派生類。

ByteArrayContent

FormUrlEncodedContent

MultipartContent

MultipartFormDataContent

StreamContent

StringContent

 

 

 

 

不管是Void,object,IHttpActionResult都將生成HttpResponseMessage。

IhttpActionResult接口中只定義了一個ExecuteAsync方法

Task<HttpResponseMessage> ExecuteAsync(CancellationToken cancellationToken);

所以IHttpActionResult可以很容易得到HttpResponseMessage

 

源碼

Github: https://github.com/BarlowDu/WebAPI (API_3)