function xmlhttpcls(url, verb)
{
   var request = get_xmlhttp_obj();   
   this.callback = null;
   var params = []; 
   //
  this.add = function (pname, pvalue)
  {
    params[params.length] = new param(pname, pvalue);
  }   
   //
   this.getText = function()
   {
        return request.responseText;
   } 
   //
   this.getXml = function()
   {
        return request.responseXML;
   }
   //
   this.send = function()
   {  
       var callback =  this.callback;
       request.onreadystatechange = function()
       {
            if (request.readyState == 4)
            {                
                if(request.status == 200)
                    callback(); 
                else
                {
                    document.write("ERR[" + request.status + "] : " + request.statusText
                        + "<br>" + url + "<br>" + getUrlParamString(params));
                } 
            }
       };
       
       if (verb != null && verb == "post")
       {            
            request.open("POST",url,true);
            request.setRequestHeader("Content-Type","application/x-www-form-urlencoded"); 
            request.setRequestHeader("If-Modified-Since","0"); 
            request.send(getUrlParamString(params)); 
       }
       else
       {
            var urlparams = getUrlParamString(params);
            if (urlparams != null)
            {
                 url =  url + "?" + urlparams;
            } 
            request.open("GET",url,true);
            request.setRequestHeader("If-Modified-Since","0");
            request.send(null);
       }
   }
  //
  var getUrlParamString = function(ps)
  {
        var urlString = null;
        if (ps.length > 0) 
        {
             urlString = "";
             for (var i = 0 ; i < ps.length; i++)
             {
                  urlString = urlString + (i == 0 ? "" : "&");
                  urlString += ps[i].name + "=" + ps[i].value;
             } 
        }
        return urlString;
  }
  //
}

function param(pname, pvalue)
{
    this.name = pname;
    this.value = pvalue; 
}

function get_xmlhttp_obj()
{
    var http_request = null;
    if(window.XMLHttpRequest)	//其他浏览器 Mozilla,
	{
		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){}
		}
	}
	return http_request;
}