ajax自定义header跨域访问webapi 405异常的解决方法

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

1 在global中对options方法进行预处理,返回服务支持的header类型

        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();
            }
        }

2 在Web.config中设置跨域参数

    <httpProtocol>
      <customHeaders>
        <add name="Access-Control-Allow-Origin" value="*" />
        <add name="Access-Control-Allow-Headers" value="*" />
        <add name="Access-Control-Allow-Methods" value="*" />
      </customHeaders>
    </httpProtocol>

3 浏览器经过预处理请求后即可自动访问原始请求,请求调用顺序如下

OPTIONS预处理请求:

OPTIONS http://localhost:8225/api/UserInfo/QueryUserByParam/ HTTP/1.1
Host: localhost:8225
Connection: keep-alive
Access-Control-Request-Method: POST
Origin: http://localhost:5964
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.101 Safari/537.36
Access-Control-Request-Headers: accept, content-type, token
Accept: */*
Referer: http://localhost:5964/Page/UserPage.aspx
Accept-Encoding: gzip, deflate, sdch
Accept-Language: zh-CN,zh;q=0.8

预处理请求成功:

HTTP/1.1 200 OK
Server: Microsoft-IIS/10.0
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
Access-Control-Allow-Methods: POST,GET,PUT,PATCH,DELETE,OPTIONS
X-SourceFiles: =?UTF-8?B?RDpcQ29kZVx0b2dvXOa6kOS7o+eggVx0cnVua1xUb2dvXDAxLlRvR28uV2ViQXBpXGFwaVxVc2VySW5mb1xRdWVyeVVzZXJCeVBhcmFtXA==?=
X-Powered-By: ASP.NET
Access-Control-Allow-Origin: *
Access-Control-Allow-Headers: *
Access-Control-Allow-Methods: *
Date: Tue, 22 Dec 2015 15:19:22 GMT
Content-Length: 0

浏览器自动发出原始请求:

GET http://localhost:8225/api/Common/GetUserTypes HTTP/1.1
Host: localhost:8225
Connection: keep-alive
Accept: */*
Origin: http://localhost:5964
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.101 Safari/537.36
Token: dQTvMagtBk2cJg5WrpmcKQ
Referer: http://localhost:5964/Page/UserPage.aspx
Accept-Encoding: gzip, deflate, sdch
Accept-Language: zh-CN,zh;q=0.8