学习笔记HttpApplication处理管道

当浏览器发送一个请求道服务器时, 实际上需要经过上图所示的流程, 该过程可以概括为:
"请求 ---> IIS ---> (检查IIS配置后)ASP.NET ---> HttContext ---> HttpApplication"
此时, 就进入了HttpApplication处理管道, 只要是ASP.NET的请求, 都会经过这个管道, 并且每一个请求都会经过这个处理管道. 而我们所熟悉的页面处理只是该流程第11步之后才开始执行的(Page_PreInit、Page_Init、Page_InitComplete、Page_PreLoad、Page_Load、Page_LoadComplete、Page_PreRender、Page_PreRenderComplete、SaveState、SaveStateComplete、Render), 而对于不同类型的文件(aspx、ashx、asmx等)则是在第7步之后进行选择的, 系统会根据文件扩展名, 为该文件映射对应的HttpHandler类.

我们实现HttpApplication的事件处理有两种方法: 即Global.aspx和IHttpModule两种方法, 更专业的方法是通过IHttpModule接口完成.

一: Globle.aspx
在Globle.aspx文件中, Application_Start方法将只能在应用程序调用第一个资源(如: 页面)时被执行, 且只能执行一次. 由于只能调用一次, 所以最好只设置静态数据(类成员), 不要设置实例数据, 因为实例数据只能有HttpAppliation类的第一个实例调用.
由于Application_Error可能发生在应用程序的任何阶段, 所以只有Application_end在应用程序生命周期最后会被调用且一定会被调用, 而Session_Start用于启动新会话, 注意: 只有当会话状态模式为"InProc"时, 才会引发Session_End时间, 其他模式(StateServer或SqlServer模式)将不会引发该事件.

//Default.aspx

代码

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:label ID="lbl_time" runat="server" text="Label"></asp:label>
    </div>
    </form>
</body>
</html>

//Default.aspx.cs

代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void Page_PreRender(object sender, EventArgs e)
    {
        //DateTime time = DateTime.Parse(this.Context.Items["begin"].ToString());
        DateTime time = DateTime.Parse(this.Application["begin"].ToString());
        this.lbl_time.Text = "页面累计运行时间为: " + (DateTime.Now - time).TotalMilliseconds.ToString() + " 毫秒! ";
    }
}

//Global.asax

代码

<%@ Application Language="C#" %>

<script runat="server">

    void Application_Start(object sender, EventArgs e) 
    {
        // Code that runs on application startup
        DateTime begin = DateTime.Now;
        
        //使用HttpContext状态管理传递参数, 此种方法只能用一次, 由于Application_Start只执行一次, 新的HttpApplication对象无法使用
        //HttpContext context = HttpContext.Current;
        //context.Items["begin"] = begin;

        this.Application["begin"] = begin;  //保存到全局状态
    }
    
    void Application_End(object sender, EventArgs e) 
    {
        //  Code that runs on application shutdown

    }
        
    void Application_Error(object sender, EventArgs e) 
    { 
        // Code that runs when an unhandled error occurs

    }

    void Session_Start(object sender, EventArgs e) 
    {
        // Code that runs when a new session is started

    }

    void Session_End(object sender, EventArgs e) 
    {
        // Code that runs when a session ends. 
        // Note: The Session_End event is raised only when the sessionstate mode
        // is set to InProc in the Web.config file. If session mode is set to StateServer 
        // or SQLServer, the event is not raised.

    }
       
</script>

二: 通过HttpModule接口完成:

2.1 通过HttpModule实现页面时间

//default.aspx

代码

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:Label ID="lbl_pagetime" runat="server" Text="页面开销"></asp:Label>
    </div>
    </form>
</body>
</html>

//default.aspx.cs

代码

using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        System.Threading.Thread.Sleep(5000);
    }

    protected void Page_PreRenderComplete(object sender, EventArgs e)
    {
        DateTime end = DateTime.Now;
        //HttpContext context = HttpContext.Current;    //这个时候有页面对象, 可以直接通过this.Context属性获得


        TimeSpan span = end - this.Context.Timestamp;

        this.lbl_pagetime.Text = string.Format("aspx中处理---页面执行时间为: {0}毫秒",span.TotalMilliseconds);
    }
}

//web.config

<system.web>
      <httpModules>
        <add name="PageTimeModule" type="Page.PageTime"/>
      </httpModules>
</system.web>

//App_Code中PageTime.cs

代码

using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

namespace Page
{
    /// <summary>
    /// Summary description for PageTime
    /// </summary>
    public class PageTime : IHttpModule
    {
        //方法1：
        DateTime begin;
        DateTime end;

        public PageTime()
        {
            //
            // TODO: Add constructor logic here
            //
        }

        #region IHttpModule Members

        public void Dispose()
        {
            // 没有什么资源要清空
        }

        public void Init(HttpApplication application)   //避免与HttpContext混淆, 改名
        {
            application.BeginRequest += new EventHandler(Application_BeginRequest); //在管道的第一个事件中注册
            application.EndRequest += new EventHandler(Application_EndRequest); //管道的最后一个事件
        }

        void Application_EndRequest(object sender, EventArgs e)
        {
            //throw new NotImplementedException();
            end = DateTime.Now;

            TimeSpan span = end - begin;

            HttpContext context = HttpContext.Current;

            System.IO.TextWriter tw = context.Response.Output;
            tw.WriteLine(string.Format("执行事件为: {0} 毫秒! ", span.TotalMilliseconds));

            //方法2：
            DateTime begin1 = context.Timestamp;
            DateTime end1 = DateTime.Now;
            TimeSpan span2 = end - begin;
            tw.WriteLine(string.Format("执行事件为: {0} 毫秒! ", span.TotalMilliseconds));
        }

        void Application_BeginRequest(object sender, EventArgs e)
        {
            //throw new NotImplementedException();
            begin = DateTime.Now;
        }

        #endregion
    }
}

2.2 通过HttpModule实现用户登陆的状态管理

//LoginModel.cs, HttpModule接口实现类

代码

using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

namespace Login
{
    /// <summary>
    /// Summary description for LoginModule
    /// </summary>
    public class LoginModule : IHttpModule
    {
        public LoginModule()
        {
            //
            // TODO: Add constructor logic here
            //
        }

        #region IHttpModule Members

        public void Dispose()
        {
            //throw new NotImplementedException();
        }

        public void Init(HttpApplication application)
        {
            //throw new NotImplementedException();
            application.AuthenticateRequest += new EventHandler(Application_AuthenticateRequest);   //在管道中处理AuthenticateRequest事件
        }

        void Application_AuthenticateRequest(object sender, EventArgs e)
        {
            //throw new NotImplementedException();
            HttpContext context = HttpContext.Current;

            HttpCookie cookie = context.Request.Cookies["UserName"];    //查看是否存在cookie
            if (cookie != null)
            {
                //从cookie中取出名字, 放到context中, 以便在PreRequestHandlerExecute之后执行的页面处理事件中获得其中的值
                string name = cookie.Value;
                context.Items["loggedname"] = name;
            }
        }

        #endregion
    }
}

//default.aspx

代码

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:Label ID="lbl_welcome" runat="server" Text="欢迎信息! "></asp:Label>
        <asp:LinkButton ID="lbtn_loggout" runat="server" onclick="lbtn_loggout_Click">注销</asp:LinkButton>
        <asp:HyperLink ID="hlnk_loggin" runat="server" NavigateUrl="~/Login.aspx">登陆</asp:HyperLink>
    </div>
    </form>
</body>
</html>

//default.aspx.cs

代码

using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (this.Context.Items["loggedname"] != null)
        {
             this.lbl_welcome.Text = string.Format("{0}, 您好! 欢迎回来! ", this.Context.Items["loggedname"]);
             this.hlnk_loggin.Visible = false;
             this.lbtn_loggout.Visible = true;
        }
        else
        {
             this.lbl_welcome.Text = string.Format("对不起, 您还没有登录! ");
             this.lbtn_loggout.Visible = false;
             this.hlnk_loggin.Visible = true;
        }

    }
    protected void lbtn_loggout_Click(object sender, EventArgs e)
    {
        HttpCookie cookie = this.Request.Cookies["UserName"];   //从请求里找cookie

        cookie.Expires = new DateTime(1900 ,1 , 1);

        this.Response.SetCookie(cookie);    //重新设置cookie
        this.Response.Redirect("Login.aspx");
    }
}

//login.aspx

代码

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Login.aspx.cs" Inherits="Login" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <span>用户名: </span>
        <asp:TextBox ID="txt_username" runat="server"></asp:TextBox><br/>
        <span>密码: </span>
        <asp:TextBox ID="txt_userpass" runat="server"></asp:TextBox><br />
        <hr />
        <asp:CheckBox ID="chkBox_remember" runat="server" Text="长期登陆" /><br />
        <asp:LinkButton ID="lbtn_login" runat="server" onclick="lbtn_login_Click">登陆</asp:LinkButton>
    </div>
    </form>
</body>
</html>

//login.aspx.cs

代码

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

public partial class Login : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void lbtn_login_Click(object sender, EventArgs e)
    {
        string username = this.txt_username.Text;
        string userpass = this.txt_userpass.Text;
        if (username != null && userpass != null)
        {
            DAL.CalendarUser calendar = new DAL.CalendarUser();
            if (calendar.ValidateUserByProc(username, userpass))
            {
                HttpCookie cookie = new HttpCookie("UserName");
                cookie.Value = username;

                if (this.chkBox_remember.Checked == true)
                {
                    cookie.Expires = DateTime.Now.AddDays(7);
                }

                this.Response.Cookies.Add(cookie);  //发cookie给可户端

                this.Response.Redirect("default.aspx"); //重定向到default.aspx
            }
        }
    }
}

//web.config

代码

<system.web>
    <httpModules>
      <add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
      <add name="LoginModule" type="Login.LoginModule"/>
    </httpModules>
</system.web>

//DAL- Calendar.cs

代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace DAL
{
    public class CalendarUser   //DAL层通过SqlHelper访问数据库
    {
        //CalendarUser类提供关于日历用户的功能, 如: 创建用户
        //DateTime是值类型, 而值类型没有与Sql中Null的对应, 加?表示可空类型, 即允许值类型为空
        public int CreateUser(string username, string userpass, string email, DateTime? birthday)
        {
            int result = -1;

            //定制的参数是根据SqlHelper的方法来选的
            string connectionStr = CalendarHelper.ConnectionString;
            string sqlText = @"insert into T_UserInfo(username, userpass,email,birthday)
                                               values(@username,@userpass,@email,@birthday)";
            System.Data.CommandType cmdType = System.Data.CommandType.Text;

            System.Data.SqlClient.SqlParameter p_username = new System.Data.SqlClient.SqlParameter("@username", System.Data.SqlDbType.NVarChar);
            System.Data.SqlClient.SqlParameter p_userpass = new System.Data.SqlClient.SqlParameter("@userpass",System.Data.SqlDbType.NVarChar);
            System.Data.SqlClient.SqlParameter p_email = new System.Data.SqlClient.SqlParameter("@email", System.Data.SqlDbType.NVarChar);
            System.Data.SqlClient.SqlParameter p_birthday = new System.Data.SqlClient.SqlParameter("@birthday",System.Data.SqlDbType.DateTime);

            p_username.Value = username;
            p_userpass.Value = userpass;
            p_email.Value = email;
            p_birthday.Value = birthday;

            System.Data.SqlClient.SqlParameter[] paras
                = new System.Data.SqlClient.SqlParameter[] { p_username, p_userpass, p_email, p_birthday };

            result = Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteNonQuery(connectionStr, cmdType,sqlText, paras);

            return result;
        }

        public int CreateUserByProc(string username, string userpass, string email, DateTime? birthday)
        {
            //定制的参数是根据SqlHelper的方法来选的
            string connectionStr = CalendarHelper.ConnectionString;
            string sqlText = "SP_CreateUserProc";

            System.Data.CommandType cmdType = System.Data.CommandType.StoredProcedure;

            System.Data.SqlClient.SqlParameter p_username = new System.Data.SqlClient.SqlParameter("@username", System.Data.SqlDbType.NVarChar);
            System.Data.SqlClient.SqlParameter p_userpass = new System.Data.SqlClient.SqlParameter("@userpass", System.Data.SqlDbType.NVarChar);
            System.Data.SqlClient.SqlParameter p_email = new System.Data.SqlClient.SqlParameter("@email", System.Data.SqlDbType.NVarChar);
            System.Data.SqlClient.SqlParameter p_birthday = new System.Data.SqlClient.SqlParameter("@birthday", System.Data.SqlDbType.DateTime);
            System.Data.SqlClient.SqlParameter p_return = new System.Data.SqlClient.SqlParameter("@returnValue",System.Data.SqlDbType.Int);

            p_username.Value = username;
            p_userpass.Value = userpass;
            p_email.Value = email;
            p_birthday.Value = birthday;

            p_return.Direction = System.Data.ParameterDirection.ReturnValue;

            System.Data.SqlClient.SqlParameter[] paras
                = new System.Data.SqlClient.SqlParameter[] { p_username, p_userpass, p_email, p_birthday,p_return};

            Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteNonQuery(connectionStr, cmdType, sqlText, paras);

            //执行完存储过程后, 获取返回值
            return (int)p_return.Value;
        }

        public bool ValidateUserByProc(string username, string userpass)
        {
            //定制的参数是根据SqlHelper的方法来选的
            string connectionStr = CalendarHelper.ConnectionString;
            string sqlText = "SP_ValidateUserByProc";

            System.Data.CommandType cmdType = System.Data.CommandType.StoredProcedure;

            System.Data.SqlClient.SqlParameter p_username = new System.Data.SqlClient.SqlParameter("@username", System.Data.SqlDbType.NVarChar);
            System.Data.SqlClient.SqlParameter p_userpass = new System.Data.SqlClient.SqlParameter("@userpass", System.Data.SqlDbType.NVarChar);
            System.Data.SqlClient.SqlParameter p_return = new System.Data.SqlClient.SqlParameter("@returnValue", System.Data.SqlDbType.Int);

            p_username.Value = username;
            p_userpass.Value = userpass;

            p_return.Direction = System.Data.ParameterDirection.ReturnValue;

            System.Data.SqlClient.SqlParameter[] paras
                = new System.Data.SqlClient.SqlParameter[] { p_username, p_userpass, p_return };

            Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteNonQuery(connectionStr, cmdType, sqlText, paras);

            //执行完存储过程后, 获取返回值
            return (int)p_return.Value == 1;    //返回1表示不存在, 即验证成功
        }
    }
}

//CalendarHelper.cs

代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace DAL
{
    public class CalendarHelper //为DAL层提供连接串
    {
        private static readonly string connectionStr = System.Configuration.ConfigurationManager.ConnectionStrings["MsSql"].ConnectionString;

        public static string ConnectionString   //对外提供连接串
        {
            get
            {
                return connectionStr;
            }
        }
        
    }
}

//SqlHelp.cs, 可以到网上去下载

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原文地址：https://www.cnblogs.com/cs_net/p/1883706.html