$(document).ready(function(){
    $("#UserLogin").click(function(){
        var logintype=$("#LoginType").val();
        var username=$("#UserName").val();
        var userpwd=$("#UserPwd").val();
        if(username=='')
        {
            alert('请输入用户名！');
            return false;
        }
        if(userpwd=='')
        {
            alert('请输入密码！');
            return false;
        }
        $.ajax({
            type:"POST",
            contentType: "application/json",
            url:"/user/login.ashx",
            data:"{LoginType:"+logintype+",UserName:"+username+",UserPwd:"+userpwd+"}",
            dataType: 'json',
            success: function(result) {     //回调函数，result，返回值
                $("#Login").html(result);
            },
            error:function(){
                alert('错误');
            }
        });
    });
});

IUserLogin userlogin = new IUserLogin();
        public void ProcessRequest(HttpContext context)
        {
            string LoginType = Convert.ToString(context.Request.QueryString["LoginType"]);
            string UserName = Convert.ToString(context.Request.QueryString["UserName"]);
            string UserPwd = Convert.ToString(context.Request.QueryString["UserPwd"]);
            UserInfo info = new UserInfo();
            if (LoginType == string.Empty || LoginType == null || LoginType == "")
                context.Response.Write("参数错误！");
            if (LoginType == "id")
                info.Userid = Convert.ToInt32(UserName);
            if (LoginType == "user")
                info.UserName = UserName;
            if (LoginType == "email")
                info.Email = UserName;
            info.UserPwd = UserPwd;
            context.Response.Write(userlogin.UserLogin(LoginType, info));
        }