webApi跨域Cross问题的简单解决

新建过滤器类：

 public class CrossSite
    {
        public class CrossSiteAttribute : ActionFilterAttribute
        {
            private const string Origin = "Origin";
            private const string AccessControlAllowOrigin = "Access-Control-Allow-Origin";
            private const string originHeaderdefault = "*";
            public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
            {
                actionExecutedContext.Response.Headers.Add(AccessControlAllowOrigin, originHeaderdefault);
            }
        }
    }　　

在控制器方法上加上过滤器标签：

 [CrossSite]
        public HttpResponseMessage GetExchangeChart(string filters)
        {
            HttpResponseMessage response = null;
            var list = BLL.GetList(filters);
            response = GetHttpResponseMessage(200, "OK", new { List = list });
            //返回的被组织的数据
            return response;

        }