当用户点击一个链接的时候，记录下用户在这个session用点击了这个资源：
在链接中触发onlick函数, onlick=ClickLog(clickLogText), 这是一个用ajax处理的异步请求 。
js文件中的代码：
function ClickLog(clickLogText) {
    //alert("fefffffffffffe");
    var xmlHttp;
    try {
        // Firefox, Opera 8.0+, Safari
        xmlHttp = new XMLHttpRequest();
    }
    catch (e) {
        // Internet Explorer
        try {
            xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
        }
        catch (e) {
            try {
                xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
            }
            catch (e) {
                alert("您的浏览器不支持AJAX！");
                return false;
            }
        }
    }
    xmlHttp.open("GET", "/WriteLog.aspx?text=" + clickLogText, true);
    xmlHttp.send(null);
//    xmlHttp.onreadystatechange = function() {
//        if (xmlHttp.readyState == 4) {
//            不需要界面响应，
//        }
//    }
 
其中WriteLog.aspx.cs中的代码是：这里要注意一个多线程的问题，因为多个用户可能同时需要操作一个文件。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Threading;
using System.IO;
namespace Gucas
{
    public partial class WriteLog : System.Web.UI.Page
    {
        static Mutex m_WriteMutex = new Mutex();
        protected void Page_Load(object sender, EventArgs e)
        {
            string text = Request.QueryString["text"];
            
            string fileName = @".\Log\ClickLog" + DateTime.Now.ToString(".yyyMMdd");
            writeLine(fileName,text);
        }
       
        public void writeLine(string fileName, string dataText)
        {
            FileStream fs = null;
            StreamWriter sw = null;
            //用于处理多线程
            m_WriteMutex.WaitOne();
            try
            {
                //CHECK文件存在不
                if (!File.Exists(fileName))
                {
                    FileStream tempfs = File.Create(fileName);
                    tempfs.Close();
                }
                fs = new FileStream(fileName, FileMode.Append, FileAccess.Write, FileShare.None);
                fs.Seek(0, System.IO.SeekOrigin.End);
                sw = new StreamWriter(fs, System.Text.Encoding.UTF8);
                sw.WriteLine(dataText);
                if (sw != null)
                {
                    sw.Close();
                    sw = null;
                }
                if (fs != null)
                {
                    fs.Close();
                    fs = null;
                }
            }
            catch (Exception ex)
            {
            }
            finally
            {
                try
                {
                    if (sw != null)
                    {
                        sw.Close();
                        sw = null;
                    }
                    if (fs != null)
                    {
                        fs.Close();
                        fs = null;
                    }
                }
                catch
                {
                }
                m_WriteMutex.ReleaseMutex();
            }
          
        }
    }
}

}