Question

怎样使用AJAX技术实现页面的定时刷新

Answer 1

function createXMLHttpRequest()
{
var g_xhRequest=null;
try
{
g_xhRequest= new ActiveXObject("Msxml2.XMLHTTP");
}
catch(e)
{
g_xhRequest=null;
}
if(g_xhRequest==null)
{
try
{
g_xhRequest=new ActiveXObject("Microsoft.XMLHTTP");
}
catch(e)
{
g_xhRequest=null;
}
if(g_xhRequest==null)
{
try
{
g_xhRequest= new XMLHttpRequest();
}
catch(e)
{
g_xhRequest= null;
}
}
}
return g_xhRequest;
}

function SendRequest(url,callback)
{
var g_xhRequest=null;
g_xhRequest=createXMLHttpRequest();
if(g_xhRequest!=null&&(g_xhRequest.readyState!=0&&g_xhRequest.readyState!=4))
{
g_xhRequest.abort();
}
g_xhRequest=createXMLHttpRequest();
if(g_xhRequest==null)
{
window.status="Global: XMLHttpRequest not supported";
}
try
{
g_xhRequest.onreadystatechange=createFunction(null,"updatePage",callback,g_xhRequest);
g_xhRequest.open("GET",url,true);
g_xhRequest.send(null);
}catch(e)
{
window.status="Global: XMLHttpRequest Send Error:["+e+"]";
}
}
function updatePage(callback,g_xhRequest)
{
if(g_xhRequest.readyState == 4)
{
if(g_xhRequest.status == 200)
{
callback(g_xhRequest.responseText);
}
else if (g_xhRequest.status == 404)
{
window.status="File lost!";
}
else if (g_xhRequest.status == 500)
{
window.status="server Error!";
}
else
{
window.status="Error: status code is " + g_xhRequest.status;
}
}
}
//========================通讯框架==============================
//========================消息框架==============================
//将有参数的函数封装为无参数的函数
function createFunction(obj,strFunc)
{
var args=[]; //定义args用于存储传递给事件处理程序的参数
if(!obj)obj=window; //如果是全局函数则obj=window;
//得到传递给事件处理程序的参数
for(var i=2;i<arguments.length;i++)args.push(arguments[i]);
//用无参数函数封装事件处理程序的调用
return function(){ obj[strFunc].apply(obj,args);}//将参数传递给指定的事件处理程序
}
//========================消息框架==================