如何统计网站访问量，代码实现使用全局变量 Application,start,end,Session_start,Session_end事件

void Application_Start(object sender, EventArgs e)
{
// 在应用程序启动时运行的代码
long totalCount = 0; //总访问数
int todayCount = 0;//今天在线人数
//先从XML中取得访问数
string xmlFilePath = Server.MapPath("~/") + "App_Data//xmls//count.xml"; //XML文件路径
DataSet ds = new DataSet();
ds.ReadXml(xmlFilePath);
totalCount = Int64.Parse(ds.Tables[0].Rows[0]["TotalCount"].ToString().Trim());
//设置Application，设置在线数量，总访问数量
Application["total_count"] = totalCount;
Application["today_count"] = todayCount;
}
void Session_Start(object sender, EventArgs e)
{
// 在新会话启动时运行的代码
Application.Lock();//锁定
long totalCount = 0; //总访问数
int todayCount = 0;//今天访问数
totalCount = Convert.ToInt64(Application["total_count"]);
todayCount = Convert.ToInt32(Application["today_count"]);
totalCount++;//用户登录，以后才修改访问总数
todayCount++;//在线用户数量加 1
Application["total_count"] = totalCount;
Application["today_count"] = todayCount;
//把访问数写如到XML文件中
string xmlFilePath = Server.MapPath("~/") + "App_Data/xmls/count.xml"; //XML文件路径
XmlDocument xmlObj = new XmlDocument();
xmlObj.Load(xmlFilePath);
XmlNode xmlRootOjb = xmlObj.SelectSingleNode("Web/AccessInfo/TotalCount");
xmlRootOjb.InnerText = totalCount.ToString();//增加总的访问量，并修改xml总访问量的值
xmlObj.Save(xmlFilePath);
Application.UnLock();//解锁
}
void Session_End(object sender, EventArgs e)
{ //这里主要计算登录用户
Application.Lock();
Application["today_count"] = Int32.Parse(Application["today_count"].ToString()) - 1;
//当用户离开站点的时候,在线总数减1
Application.UnLock();
}