/**
*
* @author: 傻傻的七
* @link: javafans.net
* @version: 1.0
*
* @param string   url      
* @param string   callback  回调函数
* @param string  data      post数据
*
* @return void
*/
function  ajax_read(url, callback, data)
{
    // init
    url += url.indexOf("?") >= 0 ? "&" : "?";
    url += "random_download_url=" + Math.random();
    
    if (typeof data == 'undefined')
    {
        var data = null;
    }

    method = data ? 'POST' : 'GET';
    
    // create XMLHttpRequest object
    if (window.XMLHttpRequest)
    {
        var objXMLHttpRequest = new XMLHttpRequest();
    }
    else
    {
        var MSXML = ['MSXML2.XMLHTTP.6.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP.5.0', 'MSXML2.XMLHTTP.4.0', 'MSXML2.XMLHTTP', 'Microsoft.XMLHTTP'];
        for(var n = 0; n < MSXML.length; n ++)
        {
            try
            {
                var objXMLHttpRequest = new ActiveXObject(MSXML[n]);        
                break;
            }
            catch(e)
            {
            }
        }
    }
    
    // send request
    with(objXMLHttpRequest)
    {
        //setTimeouts(30*1000,30*1000,30*1000,30*60*1000);
        try
        {
            open(method, url, true);
            
            if (method == 'POST')
            {
                setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8');
            }
            
            send(data);            
        }
        catch(e)
        {
            alert(e);
        }
        
        // on ready
        onreadystatechange = function()
        {
            if (objXMLHttpRequest.readyState == 4)
            {
                callback(objXMLHttpRequest.responseText, objXMLHttpRequest.status);
                delete(objXMLHttpRequest);
            }
        }
    }
}