Jquery跨域调用后台方法

     //前端JS

	function CallHandlerByJquery()

	{

            var url = "http://" + window.location.hostname + "/Helper.ashx?FLAG=2&BIZINST_GUID=276259&callback=?&rand="+Math.random();

            $.ajaxSettings.async = false;

            $.getJSON(url, function (data)

			{

			  alert(data.state + "|" + data.msg);

			});

	}

	//后台方法

	public void ProcessRequest(HttpContext context)

        {

            string jsonResult = string.Empty;

            string callback = context.Request.QueryString["callback"];

			//业务逻辑

            jsonResult = "{state:'0',msg:'操作失败'}";

        }

        context.Response.ContentType = "application/json";

        context.Response.Write(callback + "(" + jsonResult + ")");

        context.ApplicationInstance.CompleteRequest();