ASP.NET WebAPI 03 返回结果

在WebAPI中HttResponseMessage作为消息返回，而在ApiController中我们经常讲四类数据作为返回值，void,object(可序列化),IHttpActionResult,HttpResponseMessage,

Void与object

Void:返回状态码200,无数据

Object: 返回状态码200,数据

IHttpActionResult

    public interface IHttpActionResult
    {

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

　　

WebAPI为我们定义了一IHttpActionResult接口，从命名我们就可以来它是作为Action执行的返回结果。

在WebAPI总已经定义了很多实现了IHttpActionResult的类：

这些类大致可以分为：只有状态码，重定向，实体序列化，错误信息，201Created等几类。

状态码

CodeStatusResult：指定状态码

BadRequestResult：400

OkResult：200

NotFoundResult：404

UnAuthorizedResult：401

ConflictResult：409

InternalServerErrorResult：500

重定向

状态码302，并返回重定向url

RedirectResult：按绝对路径

RedirectToRouteResult：按路由

WebApi为我们提供了一个UrlHelp类，可实现路由向绝对路径的转换

            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);

　　

实体序列化

FormattedContentResult<T>：自定义序列化方式与状态码

NegotiatedContentResult<T>：自定义状态码，根据请求头信息匹配序列化类型

OkNegotiatedContentResult<T>：状态码200，根据请求头信息匹配序列化类型

JsonResult<T>：状态码200,Json序列化

错误信息

ExceptionResult：500, eg: {"Message":"出现错误。","ExceptionMessage":"未实现该方法或操作。","ExceptionType":"System.NotImplementedException","StackTrace":null}

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

InvalidModelStateResult：400，Model绑定错误,eg: {"Message":"请求无效。","ModelState":{"argument":["值不在预期的范围内。"],"implemented":["未实现该方法或操作。"]}}

这三种类型最终都是装换成HttpError

201 Created

CreatedNegotiatedContentResult<T>与CreatedAtRouteNegotiatedContentResult<T>

返回"201 Created"的状态。

同时ApiController也为我们定义许多返回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表示包括状态代码和数HTTP 响应消息。在整个WebAPI中HttpResponseMessage是作为最终的请求结果，自然HttpResponseMessag可以作为Action的返回结果。如果单从返回数据上看我们可以只关心状态码（StatusCode），内容(Content)，头信息（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; }

    }

　　

其实WebAPI定义了一个ResponseMessageResult,这个类实现了IHttpActionResult接口，这个类只重载了一个构造函数，定义了一个HttpResponseResult的属性

    public class ResponseMessageResult : IHttpActionResult
    {

        public ResponseMessageResult(HttpResponseMessage response);

        public HttpResponseMessage Response { get; }

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

　　

其中WebAPI为我们定义很多HttpContent的派生类。

ByteArrayContent

FormUrlEncodedContent

MultipartContent

MultipartFormDataContent

StreamContent

StringContent

不管是Void,object,IHttpActionResult都将生成HttpResponseMessage。

IhttpActionResult接口中只定义了一个ExecuteAsync方法

Task<HttpResponseMessage> ExecuteAsync(CancellationToken cancellationToken);

所以IHttpActionResult可以很容易得到HttpResponseMessage

源码

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