在项目Config文件中添加一下节点配置
<system.webServer>
?????<httpProtocol>
???????<customHeaders>
?????????<add name="X-Content-Type-Options" value="nosniff"/>
?????????<add name="Access-Control-Allow-Origin" value="*" />
?????????<add name="Access-Control-Allow-Headers" value="Origin, Content-Type, Accept, Authorization, X-Request-With" />
?????????<add name="Access-Control-Allow-Methods" value="GET,PUT,POST,DELETE,OPTIONS" />
?????????<add name="Access-Control-Allow-Credentials" value="true" />
???????</customHeaders>
?????</httpProtocol>
???<validation validateIntegratedModeConfiguration="false"/>
???<modules runAllManagedModulesForAllRequests="true"/>
???<handlers>
?????<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,POST,DEBUG,PUT,DELETE,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,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness64" responseBufferLimit="0" />
?????<add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
???</handlers>
?</system.webServer>
在global.cs文件中添加一下方法
在ajax对webapi进行CORS跨域访问过程中，如果自定义header，浏览器会发出一个options的请求。
询问浏览器是否支持自定义的header类型。
webapi需要做如下处理，才能正常返回浏览器请求
protected void Application_BeginRequest(object sender, EventArgs e)
???????{
???????????var res = HttpContext.Current.Response;
???????????var req = HttpContext.Current.Request;
???????????//自定义header时进行处理
???????????if (req.HttpMethod == "OPTIONS")
???????????{
???????????????res.AppendHeader("Access-Control-Allow-Headers", "Content-Type, X-CSRF-Token, X-Requested-With, Accept, Accept-Version, Content-Length, Content-MD5, Date, X-Api-Version, X-File-Name,Token,Cookie");
???????????????res.AppendHeader("Access-Control-Allow-Methods", "POST,GET,PUT,PATCH,DELETE,OPTIONS");
???????????????res.StatusCode = 200;
???????????????res.End();
???????????}
???????}
.net跨域接口服务器端配置
原文地址：https://www.cnblogs.com/miao817/p/9811730.html