var xmlHttp = false;
try 
{
    xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
}
catch (e) 
{
    try 
    {
        xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
    } 
    catch (e2) 
    {
        xmlHttp = false;
    }
}
if (!xmlHttp && typeof XMLHttpRequest != 'undefined') 
{
    xmlHttp = new XMLHttpRequest();
}
//检查账号是否注册
function callServer() 
{
    var u_name=document.getElementById("inputusername").value;
    if(u_name=="")
    {
        alert("用户名不允许为空");
    }
    else
    {
        var url = "Ajaxadd.aspx?username=" + escape(u_name)+"&date="+new Date();
        xmlHttp.open("GET", url, true);
        xmlHttp.onreadystatechange = updatePage;
        xmlHttp.send(null);
    }  
}
function updatePage() 
{
    if (xmlHttp.readyState < 4) 
    {
        span1.innerHTML="loading...";
    }
    if (xmlHttp.readyState == 4) 
    {
        if (xmlHttp.status == 200) 
        {
            var response = xmlHttp.responseText;

            document.all.Text4.value=response;
            document.getElementById("span1").style.color="Green";
            span1.innerHTML=response;
        }
    }
} 
//登陆
function loginajax()
{
    var vusername=document.getElementById("Textusername").value;
    var vpassword=document.getElementById("Textpassword").value;
    if(vusername=="" || vpassword=="")
    {
        alert("用户名和密码不允许为空!");
    }
    else
    {
        var url = "Ajaxadd.aspx?vusername=" + escape(vusername)+"&vpassword="+escape(vpassword)+"&date="+new Date();
        xmlHttp.open("GET", url, true);
        xmlHttp.onreadystatechange = logincheck;
        xmlHttp.send(null);
    }
}
//注册
function insertajax()
{
    var vstate=document.getElementById("Text4").value;
    var username=document.getElementById("inputusername").value;
    var password=document.getElementById("inputpassword").value;
    if(vstate=="可以注册")
    {
        var url = "Ajaxadd.aspx?insertusername=" + escape(username)+"&password="+escape(password)+"&date="+new Date();
        xmlHttp.open("GET", url, true);
        xmlHttp.onreadystatechange = logincheck;
        xmlHttp.send(null);
    }
    else
    {
        alert("该账号不符合注册条件，请重新输入");
    }
}
function logincheck()
{
    if (xmlHttp.readyState < 4) 
    {
    }
    if (xmlHttp.readyState == 4) 
    {
        if (xmlHttp.status == 200) 
        {
            var response = xmlHttp.responseText;
            if(response=="0")
            {
                window.location.href="default.aspx";
            }
            if(response=="1")
            {
                alert("用户名不存在");
            }
            if(response=="2")
            {
                alert("用户名和密码不正确");
            }
        }
    }
}