function class_ajax()
{
this.ID = "ajax";
/**
  * xml请求对象
  */
this.xmlHttp = null;
/*
  * 请求的目标url
  */
this.url = "";
/**
  * http请求的方法 GET or POST
  */
this.method = "";
/**
  * 状态改变的事件触发函数
  */
this.event = "";
/**
  * 是否为异步连接
  */
this.async = true;
/**
  * REQUEST参数
  */
this.params = new Array;


/**
  * 初始化xmlHttpRequest对象
  *
  */
this.init = function(){
	/*
	try{
		this.xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
	}catch(e){
		try{
			this.xmlHttp = new XMLHttpRequest();
		}catch(e){
			this.xmlHttp = null;
		}
	}
*/

  if(this.xmlHttp == null){
   if (window.XMLHttpRequest){
          this.xmlHttp = new XMLHttpRequest();
      }else if (window.ActiveXObject)
       {
          this.xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
          if(!this.xmlHttp){
          	this.xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
          }
      }
   }

  if(this.xmlHttp == null){
   alert("invalid xmlHttpRequest!");
   return false;
  }
}//end function

/**
  * 设置目标请求方法
  */
this.set_method = function(method){
	if(method != 'POST' && method != 'GET'){ 
		alert("invalid method!");
		return false;
  }
  this.method = method;
}//end function

/**
  * 获取目标请求方法
  */
this.get_method = function()
{
  return this.method;
}//end function

/**
  * 设置状态该表要触发的事件
  */
this.set_event = function(event)
{
  this.event = event;
}//end function

/**
  * 获取 event
  */
this.get_event = function()
{
  return this.event;
}//end function

/**
  * 设置要请求的目标url
  */
this.set_url = function(url)
{
  this.url = url;
}//end function

/**
  * 获取 url
  */
this.get_url = function()
{
  return this.url;
}//end function

/**
  * 添加REQUEST 参数
  */
this.add_param = function(key, val)
{
  var tmpCount = this.params.length;
  this.params[tmpCount] = key + "=" + val; 
  }//end function
  
  /**
   * 设置请求为异步连接
   */
  this.set_async = function()
  { 
   this.async = true;
  }//end function
  
  /**
   * 取消异步连接，即设置为同步连接
   */
  this.set_sync = function()
  {
   this.async = false;
  }//end function
  
  /**
  * 发送请求
  */
this.submit = function()
{
  this.xmlHttp.onreadystatechange = this.event;
  var send_params = null;
  if(this.params.length > 0)
  {
   send_params = this.params.join('&');
   if(this.method == 'POST')
   {
    this.xmlHttp.open(this.method, this.url, this.async);
    //this.xmlHttp.setRequestHeader("Method", this.method + this.url + " HTTP/1.1");
    this.xmlHttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    this.xmlHttp.send(send_params);
   }else
   {
    this.xmlHttp.open(this.method, this.url + "?" + send_params, this.async);
    this.xmlHttp.send(null);
   }
  }else
  {
    this.xmlHttp.open(this.method, this.url, this.async);
    this.xmlHttp.send(send_params);
  }
  
}//end function

/**
  * return Data
  * @param string type : "xml" or "text"
  */
this.get_content = function(type)
{
  if(type == 'xml')
  {
   return this.xmlHttp.responseXML.documentElement;
  }else
  {
   return this.xmlHttp.responseText;
  }
}

/**
  * 检测事件是否完成
  */
this.complete = function()
{
  if(this.xmlHttp.readyState == 4)
  {
   return true;
  }
  return false;
}//end function

/*
  * 检测请求是否成功
  */
this.success = function()
{
  if (this.complete() && this.xmlHttp.status == 200) {
    return true;        
  }
        return false;
}//end function

/**
  * 获取消息提示
  */
this.get_statusText = function()
{
  return this.xmlHttp.statusText;
}//end function
}//end class