function antiCacheRand(aurl){
    var dt = new Date();
    if(aurl.indexOf("?")>=0){// já tem parametros
        return aurl + "&" + encodeURI(Math.random() + "_" + dt.getTime());
    }else{ return aurl + "?" + encodeURI(Math.random() + "_" + dt.getTime());}
}

/*
url = '';
div = '';
parametros = '';
adm_ajax(url, 'GET', 'true', div, parametros);
*/

function adm_ajax(url, metodo, modo, tagRetorno, parametros){
	if (window.XMLHttpRequest){
		// code for MOZILLA
		xmlhttp=new XMLHttpRequest()
	}else if (window.ActiveXObject){
		// code for IE
		xmlhttp=new ActiveXObject("Microsoft.XMLHTTP")
	}
	url = url+'?'+parametros+'&rnd'+ Math.random() 
	url = antiCacheRand(url);

	if(metodo == "GET") {
		xmlhttp.open("GET", url, modo);
	} else {        
		xmlhttp.open("POST", url, modo);
		xmlhttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded; charset=iso-8859-1");
		xmlhttp.setRequestHeader("Cache-Control", "no-store, no-cache, must-revalidate");
		xmlhttp.setRequestHeader("Cache-Control", "post-check=0, pre-check=0");
		xmlhttp.setRequestHeader("Pragma", "no-cache");
	}    
	xmlhttp.onreadystatechange = function() {
		if(xmlhttp.readyState == 4) {
			retorno=xmlhttp.responseText
			if(document.getElementById(tagRetorno)){
				document.getElementById(tagRetorno).innerHTML=retorno
			}
		}
	}
	if(metodo == "GET") {
		xmlhttp.send(null);
	} else {        
		xmlhttp.send(parametros);
	}
}