ASP.NET解决跨域问题

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Http.Filters;

namespace Project1.Application.Web.API
{
    public class CrossSiteAttribute: System.Web.Http.Filters.ActionFilterAttribute
    {
        //使用方法：
        /*
         在需要跨域的 action 增加[CrossSite]属性

        例子：

        [CrossSite]
        [HttpPost]
        public HttpResponseMessage GetData()
        {
            StringBuilder sb = new StringBuilder();
            sb.AppendFormat(@" SELECT p.province as 'name',a.gaidu as 'value' FROM MapQueryDataBySheng a
INNER JOIN t_Province p ON a.areaid=p.id");
            DataTable dt = SQLHelper.ExecDataTable(sb.ToString(), null);
            string strJson = DataTableToJsonWithJsonNet(dt);
            return new HttpResponseMessage { Content = new StringContent(strJson, Encoding.GetEncoding("UTF-8"), "application/json") };
        }
             */

        private const string Origin = "Origin";
        /// <summary>
        /// Access-Control-Allow-Origin是HTML5中定义的一种服务器端返回Response header，用来解决资源（比如字体）的跨域权限问题。
        /// </summary>
        private const string AccessControlAllowOrigin = "Access-Control-Allow-Origin";
        /// <summary>
        ///  originHeaderdefault的值可以使 URL 或 *，如果是 URL 则只会允许来自该 URL 的请求，* 则允许任何域的请求
        /// </summary>
        private const string originHeaderdefault = "*";
        /// <summary>
        /// 该方法允许api支持跨域调用
        /// </summary>
        /// <param name="actionExecutedContext"> 初始化 System.Web.Http.Filters.HttpActionExecutedContext 类的新实例。</param>
        public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
        {
            if (actionExecutedContext != null)
            {
                actionExecutedContext.Response.Headers.Add(AccessControlAllowOrigin, originHeaderdefault);
            }
        }
    }
}