获取Flash当前所在域主域名

public function fetchDomainRootURL() : String
{
	var domainRootURL : String	= null;
	// if pure as3 project, fetch complete URL just remove 'parent'
	var completeURL : String	= this.parent.stage.loaderInfo.url;
	trace(completeURL);
	// step 1 : start with 'http'
	var httpIdx : int	= completeURL.indexOf('http');
	trace(httpIdx);
	if (httpIdx == 0)
	{
		// step 2 : the first index of '//'
		var doubleSlashsIdx : int	= completeURL.indexOf('//');
		trace(doubleSlashsIdx);
		if (doubleSlashsIdx != -1)
		{
			// step 3 : the first index of '/'
			var domainRootSlashIdx : int	= completeURL.indexOf('/', doubleSlashsIdx + 2);
			trace(domainRootSlashIdx);
			if (domainRootSlashIdx != -1)
				domainRootURL	= completeURL.substring(httpIdx, domainRootSlashIdx + 1);
		}
	}
	trace(domainRootURL);
	return domainRootURL;
}