一、文件Global.asax中，方法Application_Start()添加如下：
 // 转换为json
GlobalConfiguration.Configuration.Formatters.XmlFormatter.SupportedMediaTypes.Clear();


二、文件Web.config配置，添加GET, POST, PUT, DELETE,OPTIONS方式，如下：
<configuration>
<system.web>
    <authentication mode="None" />
    <compilation debug="true" targetFramework="4.5.2" />
    <httpRuntime targetFramework="4.5.2" maxRequestLength="2097151" executionTimeout="120" />
    <httpModules>
      <add name="ApplicationInsightsWebTracking" type="Microsoft.ApplicationInsights.Web.ApplicationInsightsHttpModule, Microsoft.AI.Web" />
    </httpModules>
  </system.web>
  <system.webServer>
    <security>
      <requestFiltering>
        <requestLimits maxAllowedContentLength="2147483647"></requestLimits>
      </requestFiltering>
    </security>
    <modules>
      <remove name="FormsAuthentication" />
      <remove name="ApplicationInsightsWebTracking" />
      <add name="ApplicationInsightsWebTracking" type="Microsoft.ApplicationInsights.Web.ApplicationInsightsHttpModule, Microsoft.AI.Web" preCondition="managedHandler" />
    </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>
    <httpProtocol>
      <customHeaders>
        <add name="Access-Control-Allow-Origin" value="*" />
        <add name="Access-Control-Allow-Headers" value="*" />
        <add name="Access-Control-Allow-Methods" value="GET, POST, PUT, DELETE,OPTIONS" />
      </customHeaders>
    </httpProtocol>
    <validation validateIntegratedModeConfiguration="false" />
  </system.webServer>
</configuration>