ASP.net WebApi POST返回405错误

我正在用asp.net后端构建Angular 5应用程序。我想发送POST请求，我通过邮递员对它进行了测试，它工作得非常好，然而，当我尝试在内部执行时，我得到了405个错误。 I用户HttpClient，标题为：newhttpheaders（{'Content-Type'：'application/json'}），与Postman相同

我试图更改web.config

  <system.webServer>
    <httpProtocol>
      <customHeaders>
        <add name="Access-Control-Allow-Origin" value="*"/>
        <add name="Access-Control-Allow-Headers" value="Origin, Authorization, X-Requested-With, Content-Type, Accept"/> 
        <add name="Access-Control-Allow-Methods" value="GET, POST, PUT, DELETE, OPTIONS"/>
      </customHeaders>
    </httpProtocol>
    <validation validateIntegratedModeConfiguration="false"/>
    <modules runAllManagedModulesForAllRequests="true">
      <remove name="WebDAVModule"/>
    </modules>
    <handlers>
      <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>
  </system.webServer>

---

}这是因为浏览器在发送主请求之前发送飞行前请求

您可以向webapi应用程序添加以下代码：global.asax.cs

protected void Application_BeginRequest()
{
    if (Request.HttpMethod == "OPTIONS") {
        Response.Flush();
    }
}

protected void Application_BeginRequest()
{
    if (Request.HttpMethod == "OPTIONS") {
        Response.Flush();
    }
}