function getHTTPObject() //获取Http请求对象，这个对象用于客户端向服务端发送异步的http请求
{ 
var http;
var browser = navigator.appName;
if(browser == "Microsoft Internet Explorer")
{
http = new ActiveXObject("Microsoft.XMLHTTP"); //如果用户使用IE，就返回XMLHTTP的ActiveX对象
}
else
{
http = new XMLHttpRequest(); //否则返回一个XMLHttpRequest对象
}
return http;
}

function ajax(div_id,div_url){//第一个填写DIV的ID,后一个填写URL地址
var http = getHTTPObject(); //获取全局的HTTP请求对象
function getFuer() //处理请求状态变化
{ 
if (http.readyState == 4) //4表示请求已完成
{
var helloStr = http.responseText; //获取服务段的响应文本
//插入响应到ID为 div_id 的DIV标签内
document.getElementById(div_id).innerHTML = helloStr; 
}
}
http.open("GET", div_url, true); //指定服务端的地址
http.onreadystatechange = getFuer; //请求状态变化时的处理函数
http.setRequestHeader("If-Modified-Since","0");
http.send(null); //发送请求
}

 //关键字导入
var http_request = false;   
  
function sendRequest(url, obj) {   
    http_request = false;   
  
    if (window.XMLHttpRequest) { // Mozilla, Safari,...   
  
        http_request = new XMLHttpRequest();   
        if (http_request.overrideMimeType) {   
            http_request.overrideMimeType('text/xml');   
        }   
    } else if (window.ActiveXObject) { // IE   
  
        try {   
            http_request = new ActiveXObject("Msxml2.XMLHTTP");   
        } catch (e) {   
            try {   
                http_request = new ActiveXObject("Microsoft.XMLHTTP");   
            } catch (e) {}   
        }   
    }   
  
    if (!http_request) { 
        return false;   
    }   
       
    http_request.onreadystatechange = function processRequest() {   
        //最后输出过程   
  
        if (http_request.readyState == 4) {   
            if (http_request.status == 200) {   
                document.getElementById(obj).innerHTML=http_request.responseText;   
                //alert(http_request.responseText);   
  
            } else {
				document.getElementById(obj).innerHTML="没有标签！";  
            }   
        }   
    }   
       
    document.getElementById(obj).innerHTML="<div class='ajaxload'>正在载入...</div>";
    http_request.open('GET', url, true);   
    http_request.send(null);   
}