Web API 接口返回值解析

• void无返回值的：在请求该方法时，返回值为空，状态吗为204

[HttpPost]
public void SaveOrder(ORDER name){
    //处理业务逻辑
}

• 返回值为IHttpActionResult类型

private readonly ORDER oRDER1 = new ORDER() { ID = "aa", NO = "10", NAME = "bb", DESC = "0" };
private readonly ORDER oRDER2 = new ORDER() { ID = "dd", NO = "20", NAME = "cc", DESC = "1" };
//StatusCode：返回带有提供的HTTP码(和一个空响应体)的响应
public IHttpActionResult GetStatusCode(){
    return StatusCode(HttpStatusCode.OK);
}
//Json：返回HTTP 200(OK)，将提供内容格式化为JSON格式，还可以使用提供的序列化器设置和字符编码来格式化内容
public IHttpActionResult GetJsonResult(int id){
    switch (id){
        case 1: return Json<List<ORDER>>(new List<ORDER> { oRDER1,oRDER2 }, new JsonSerializerSettings(), System.Text.Encoding.UTF8);
        case 2: return Json<object>(new { A = "aa", B = "bb" }, new JsonSerializerSettings(), System.Text.Encoding.UTF8);
        default: return Json<dynamic>(new { A = "aa", B = "bb" }, new JsonSerializerSettings(), System.Text.Encoding.UTF8);
    }
}
// Ok：返回HTTP 200，可以包括返回的内容
public IHttpActionResult GetOKResult(int id){
    switch (id){
        case 1: return Ok<string>("aaaa");//简化return Ok("aaaa");
        case 2: return Ok<ORDER>(oRDER1);//return Ok(oRDER1);
        default: return Ok();
    }
}
//Content：返回HTTP 200,返回内容，内容格式可以选定返回的内容，HTTP状态码，格式
public IHttpActionResult GetContent(){
    return Content(HttpStatusCode.OK, oRDER1, new JsonMediaTypeFormatter(), new MediaTypeHeaderValue("application/json"));
}
//Created：返回HTTP 201，位置头被设,为提供URL的位置
public IHttpActionResult GetCreated(){
    return Created("ActionApi", new { controller = "TestReturnData", action = "GetBadRequest" });
}
//CreateAtRoute：返回HTTP 201，位置头被设为基于提供的路由名和路由值构成的URL
public IHttpActionResult GetCreatedAtRoute(){
    return CreatedAtRoute<ORDER>("ActionApi", new { controller = "TestReturnData", action = "GetBadRequest" }, oRDER1);
}
//Redirect：返回HTTP 302，位置头被设为指定的URL位置,重定向
public IHttpActionResult GetRedirectResult(int id){
    if (id == 1){
        return Redirect("http://localhost:61218/actionapi/TestReturnData/GetContent");
    }else{
        UrlHelper helper = new UrlHelper(Request);
        IDictionary<string, object> route = new Dictionary<string, object>{
            ["controller"] = "TestReturnData",["action"] = "GetBadRequest"
        };
        return Redirect(new Uri(helper.Link("ActionApi", route)));
    }
}
//RedirectToRoute：返回HTTP302，位置头被设为基于提供的路由名和路由值构成的URL,重定向
public IHttpActionResult GetRedirectToRoute(){
    return RedirectToRoute("ActionApi", new { controller = "TestReturnData", action = "GetBadRequest" });
}
//BadRequest：返回HTTP 400，根据验证错误，可能包含一条信息或者一个自动格式化的错误类
public IHttpActionResult GetBadRequest(){
    return BadRequest("error");//也可以不包括错误信息
}
//Unauthorized：返回HTTP 401，身份验证头被设为提供的身份验证头值
public IHttpActionResult GetUnauthorized(){
    return Unauthorized(new List<AuthenticationHeaderValue>() { new AuthenticationHeaderValue("Authorization") });
}
//NotFound：返回HTTP 404 没有找到
public IHttpActionResult GetNotFoundResult(){
    return NotFound();
}
// Conflict：返回HTTP 409 冲突
public IHttpActionResult GetConflict(){
    return Conflict();
}
//InternalServerError：返回HTTP 500，可能会包含提供的异常派生出的内容
public IHttpActionResult GetInternalServerError(){
    //return InternalServerError();
    return InternalServerError(new NotImplementedException());
}

• 自定义类实现IHttpActionResult接口，该接口只有ExecuteAsync()方法

//实现接口
public class PageResult : IHttpActionResult{
    private object _value;
    private HttpRequestMessage _requestMessage;
    public PageResult(object value,HttpRequestMessage requestMessage){
        _value = value;
        _requestMessage = requestMessage;
    }
    public Task<HttpResponseMessage> ExecuteAsync(CancellationToken cancellationToken){
        var response = new HttpResponseMessage(){
            Content = new ObjectContent(typeof(object), _value, new JsonMediaTypeFormatter()),
            RequestMessage = _requestMessage
        };
        return Task.FromResult(response);
    }
}
//调用
public IHttpActionResult GetPageResult(){
    return new PageResult(new List<ORDER>() { oRDER1, oRDER2 }, Request);
}

• ResponseMessageResult同样继承于IHttpActionResult接口，HttpResponseMessage类中有HTTP状态码，HTTP响应消息Content(有很多派生类，比如StreamContent、StringContent、ByteArrayContent等)，头信息，一般用于文本流

public IHttpActionResult GetRequestMessage(){
    return ResponseMessage(new HttpResponseMessage(HttpStatusCode.OK));
}
public HttpResponseMessage GetFile(){
    string json = JsonConvert.SerializeObject(new List<ORDER>() { oRDER1, oRDER2 });
    var buffer = Encoding.UTF8.GetBytes(json);
    MemoryStream stream = new MemoryStream(buffer);
    HttpResponseMessage responseMessage = new HttpResponseMessage(HttpStatusCode.OK){
        Content = new StreamContent(stream)
    };
    responseMessage.Content.Headers.ContentType = new MediaTypeHeaderValue("text/plain");
    responseMessage.Content.Headers.Add("Content-Disposition", "attachment;filename=figure.txt");
    return responseMessage;
}
public HttpResponseMessage GetString(){
    HttpResponseMessage responseMessage = new HttpResponseMessage(HttpStatusCode.OK){
        Content = new StringContent("Hello World")    
    };
    responseMessage.Content.Headers.ContentType = new MediaTypeHeaderValue("text/html");
    //responseMessage.Content.Headers.Add("Content-Disposition", "attachment;filename=figure.txt");
    return responseMessage;
}

 

• Web API会自动序列化自定义任何返回类型，然后将序列化的值写到响应正文里，状态码统一返回200