好吧,当它在控制台中出现此错误时,我真的很讨厌它.而且我知道stackoverflow充斥着这些类型的问题.但是,我已经完成了研究,并且在我的Web API 2 Web服务中启用了CORS,我仍然遇到此错误.

这是我的Web API 2代码：

namespace WebApi.App.Controllers
{
    [EnableCors(origins: "*",headers: "*",methods: "*")]
    public class ServiceController : ApiController
    {
        [HttpGet]
        [Route("GetData")]
        public IHttpActionResult GetEmpData(DATAvars theDATA)
        {
            return Ok("WORKED! " + theDATA);            
        }

        [HttpPost]
        [Route("PostData")]
        public IHttpActionResult PostempData(DATAvars theDATA)
        {
            return Ok("WORKED! " + theDATA.theID);
        }

    }

    public class DATAvars
    {
        public string theID { get; set; }
        public string empImg { get; set; }
    }
}

和

<system.webServer>
<modules runAllManagedModulesForAllRequests="true">
  <remove name="WebDAVModule"/>
</modules>
<httpProtocol>
  <customHeaders>
    <add name="Access-Control-Allow-Origin" value="*" />
    <add name="Access-Control-Allow-Headers" value="Content-Type" />
    <add name="Access-Control-Allow-Methods" value="GET,POST,PUT,DELETE,OPTIONS" />
  </customHeaders>
</httpProtocol>
<handlers>
  <remove name="WebDAV" />
  <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
  <remove name="OPTIONsverbHandler" />
  <remove name="TRACEVerbHandler" />
  <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
</handlers>

和

namespace WebApi.App
{
    public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            config.Formatters.Clear();
            config.Formatters.Add(new JsonMediaTypeFormatter());
            config.MapHttpAttributeRoutes();
            config.EnableCors();
        }
    }
}

和

public class WebApiApplication : System.Web.HttpApplication
{
    protected void Application_Start()
    {
        GlobalConfiguration.Configure(WebApiConfig.Register);
    }

    protected void Application_BeginRequest(object sender,EventArgs e)
    {
    HttpContext.Current.response.addheader("Access-Control-Allow-Origin","*");

    if (HttpContext.Current.Request.HttpMethod == "OPTIONS" )
    { 
        //These headers are handling the "pre-flight" OPTIONS call sent by the browser
        HttpContext.Current.response.addheader("Access-Control-Allow-Methods","GET,POST" );
        HttpContext.Current.response.addheader("Access-Control-Allow-Headers","Content-Type,Accept" );
        HttpContext.Current.response.addheader("Access-Control-Max-Age","1728000");
        HttpContext.Current.Response.End();
    } 
    } 
}

然后为我的AJAX调用代码(在另一个域上托管)：

$.ajax({
    type: "POST",crossDomain: true,url: "http://dev-blahblah/newWS/PostData",beforeSend: function (xhrObj) {
        xhrObj.setRequestHeader("Content-Type","application/json");
    },data: {
        theID: "2135648792",empImg: "false"
    },dataType: "json",success: function (data) {
        console.log(data);
    },error: function (XMLHttpRequest,textStatus,errorThrown) {
        console.log(XMLHttpRequest);
    }
});

这是控制台中的错误：

控制台网络说：

Failed to load resource: the server responded with a status of 404 (Not Found)
index.html:1 XMLHttpRequest cannot load 07002. Response for preflight has invalid HTTP status code 404

现在这是SAME请求但在POSTMAN中：

我花了DAYS试图弄清楚这个和无休止的googleing找到例子,我有,但似乎所有的例子都不起作用.

我非常感谢有人让我知道我需要做什么才能使用JQUERY AJAX.

-Running it on the same domain in CHROME = WORKS

-Running it on a different domain in CHROME = DOES NOT WORK

-Running it on the same domain in IE = WORKS

-Running it on a different domain in IE = WORKS

在我的Web API web.config文件中使用以下配置部分以避免404错误.

<handlers>
  <remove name="WebDAV"/>
  <remove name="OPTIONsverbHandler" />
  <remove name="TRACEVerbHandler" />
  <remove name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" />
  <remove name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" />
  <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
  <add name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" path="*." verb="GET,HEAD,DEBUG,PATCH,OPTIONS" modules="IsapiModule" scriptprocessor="%windir%\Microsoft.NET\Framework\v4.0.30319\aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness32" responseBufferLimit="0" />
  <add name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" path="*." verb="GET,OPTIONS" modules="IsapiModule" scriptprocessor="%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_isapi.dll" preCondition="classicMode,bitness64" responseBufferLimit="0" />
  <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="GET,OPTIONS" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
  <add name="OPTIONsverbHandler" path="*" verb="OPTIONS" modules="ProtocolSupportModule" requireAccess="None" responseBufferLimit="4194304" />
</handlers>

我正在实现返回一个 JSON编码的有效载荷的Web服务.如果服务调用失败 – 例如,由于参数无效,返回JSON编码错误.不过,我不确定在这种情况下应该返回什么HTTP状态代码.

一方面,HTTP状态代码似乎适用于HTTP：即使正在返回应用程序错误,HTTP传输本身也是成功的,建议200 OK响应.

另一方面,RESTful方法似乎表明,如果调用者试图发布资源,并且请求的JSON参数无效,那么400错误请求是合适的.

我在客户端使用Prototype,它有一个很好的机制,可以根据HTTP状态代码(onSuccess和onFailure)自动调度到不同的回调,所以我试图使用状态代码来指示服务成功或失败,但是有兴趣听到有人在这个问题上有常见做法的意见或经验.

谢谢！

http状态码仅用于指示应用程序响应的状态.
正如你所说,如果json参数以某种方式无效,则400状态代码是适当的答案.

所以是的,这是一个很好的主意,使用http状态码. de plus,状态码很容易理解,因为它们不会从应用程序(Web服务)变为另一个