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);

            }

        }

    }

}