// 调用服务器程序
function makeHTTPRequest(url, respFunc) 
{
    var http_request;

	http_request = false;
	
	if (window.XMLHttpRequest) {
		http_request = new XMLHttpRequest();
		if (http_request.overrideMimeType){
			http_request.overrideMimeType('text/xml');
		} 
	} else if (window.ActiveXObject) {
		try{
			http_request = new ActiveXObject("Msxml2.XMLHTTP"); 
		} catch (e) {
			try {
				http_request = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {
				alert("无法创建请求，请关闭浏览器后重新打开本站点！");
			}
		}
	}

    showWaiting();
	
	//定义页面调用的方法;
	http_request.onreadystatechange = function() {
        if (http_request.readyState != 4) return;
		
		clrWaiting();
		if (http_request.status != 200) {
			showRequestError(http_request.responseText);
			return;
		}
		
		response = http_request.responseText;
		//response = http_request.responseXML;
		
		respFunc(response);
	};
	
	http_request.open('GET', url, true); 

	//禁止IE缓存
	http_request.setRequestHeader("If-Modified-Since", "0"); 
	http_request.setRequestHeader("Content-Type", "text/html;charset=gb2312;"); 

	//发送数据
	http_request.send(null);
}

function showWaiting()
{
	try {
	    document.getElementById("Status").innerHTML = "正在请求数据...";
  }
  catch (e)
  {
  }
}

function clrWaiting()
{
	try {
	   document.getElementById("Status").innerHTML = " ";
  }
  catch (e)
  {
  }
}

function showRequestError(responseText)
{
	try {
	    document.getElementById("Status").innerHTML = "请求失败!"; // http_request.responseText;
	    if (_DEBUG) alert(responseText);
  }
  catch (e)
  {
  }
}