asp.net Forums 之配置，缓存，多数据访问

在上一篇文章中，我谈到了asp.net Forums 之控件研究，这次我们来谈谈asp.net Forums 的配置、缓存和多数据访问。

一、配置

ANF的配置是通过ForumConfiguration类，ForumConfiguration类位于AspNetForums.Configuration命名空间下。

  

#region  VSS

/*  
* $Header: /HiForums/Components/Configuration/ForumConfiguration.cs 1     05-10-26 15:04 Jacky $ 
* 
* $History: ForumConfiguration.cs $ 
 * 
 * *****************  Version 1  *****************
 * User: Jacky        Date: 05-10-26   Time: 15:04
 * Created in $/HiForums/Components/Configuration
 * 
 * *****************  Version 1  *****************
 * User: Jacky        Date: 05-10-21   Time: 14:20
 * Created in $/HiForums/Components/Configuration
 * 
 * *****************  Version 3  *****************
 * User: Jacky        Date: 05-09-20   Time: 19:23
 * Updated in $/ASP.NET Forums/Components/Configuration
 * 
 * *****************  Version 2  *****************
 * User: Jacky        Date: 05-09-20   Time: 1:36
 * Updated in $/ASP.NET Forums/Components/Configuration
*/

#endregion 

using System;
using System.Collections;
using System.Collections.Specialized;
using System.IO;
using System.Web;
using System.Web.Caching;
using System.Xml;
using System.Configuration;
using System.Xml.Serialization;
using AspNetForums.Components;
using AspNetForums.Enumerations;

namespace AspNetForums.Configuration
{
    // *********************************************************************
    //  ForumConfiguration
    //
    /// <summary>
    /// 读取论坛配置信息,根据CS结构重构.
    /// by venjiang 2005/10/25
    /// </summary>
    /// 
    // ***********************************************************************/
    public class ForumConfiguration
    {
        #region 成员字段
        public static readonly string CacheKey = "ForumsConfiguration";
        private Hashtable providers = new Hashtable();
        private Hashtable extensions = new Hashtable();
        private static readonly Cache cache = HttpRuntime.Cache;
        private string defaultProvider;
        private string defaultLanguage;
        private string forumFilesPath;
        private bool disableBackgroundThreads = false;
        private bool disableIndexing = false;
        private bool disableEmail = false;
        private string passwordEncodingFormat = "unicode";
        private int threadIntervalEmail = 15;
        private int threadIntervalStats = 15;
        //private SystemType systemType = SystemType.Self;
        private short smtpServerConnectionLimit = -1;
        private bool enableLatestVersionCheck = true;
        private string uploadFilesPath = "/Upload/";
        private XmlDocument XmlDoc = null;
        #endregion

        #region 构造器
        public ForumConfiguration(XmlDocument doc)
        {
            XmlDoc = doc;
            LoadValuesFromConfigurationXml();
        }
        #endregion

        #region 获取XML节点
        public XmlNode GetConfigSection(string nodePath)
        {
            return XmlDoc.SelectSingleNode(nodePath);
        }

        #endregion
        /*
                public static ForumConfiguration GetConfig()
                {
                    return (ForumConfiguration) ConfigurationSettings.GetConfig("forums/forums");
                }
        */
        #region 获取配置信息实例
        public static ForumConfiguration GetConfig() 
        {
            ForumConfiguration config = cache.Get(CacheKey) as ForumConfiguration;
            if(config == null)
            {
                string path;
                if(HttpContext.Current != null)
                    path = HttpContext.Current.Server.MapPath("~/Forums.config");
                else
                    path = Directory.GetCurrentDirectory() + Path.DirectorySeparatorChar + "Forums.config";

                XmlDocument doc = new XmlDocument();
                doc.Load(path);
                config = new ForumConfiguration(doc);
                cache.Insert(CacheKey,config,new CacheDependency(path),DateTime.MaxValue,TimeSpan.Zero,CacheItemPriority.AboveNormal,null);

                //cache.ReSetFactor(config.CacheFactor);
            }
            return config;
            
        }
        #endregion

        #region 加载配置文件设置
        internal void LoadValuesFromConfigurationXml() 
        {
            XmlNode node = GetConfigSection("Forums/Core");
            XmlAttributeCollection attributeCollection = node.Attributes;

            // 默认数据提供者
            XmlAttribute att = attributeCollection["defaultProvider"];
            if(att != null)
                defaultProvider = att.Value;
            // 默认语言
            att = attributeCollection["defaultLanguage"];
            if(att != null)
                defaultLanguage =att.Value;
            else
                defaultLanguage = "zh-CN";
            // 论坛路径
            att = attributeCollection["forumFilesPath"];
            if(att != null)
                forumFilesPath = att.Value;
            else
                forumFilesPath = "/";
            // 禁用后台线程
            att = attributeCollection["disableThreading"];
            if(att != null)
                disableBackgroundThreads = bool.Parse(att.Value);
            else
                disableBackgroundThreads = false;
            // 禁止索引
            att = attributeCollection["disableIndexing"];
            if(att != null)
                disableIndexing = bool.Parse(att.Value);
            else
                disableIndexing = false;
            // 禁止邮件
            att = attributeCollection["disableEmail"];
            if(att != null)
                disableEmail = bool.Parse(att.Value);
            else
                disableEmail = false;
            // 密码加密格式
            att = attributeCollection["passwordEncodingFormat"];
            if(att != null)
                passwordEncodingFormat = att.Value;
            else
                passwordEncodingFormat = "unicode";
            // 后中统计状态
            att = attributeCollection["threadIntervalStats"];
            if(att != null)
                threadIntervalStats = int.Parse(att.Value);
            else
                threadIntervalStats = 15;
            // 邮件队列发送间隔
            att = attributeCollection["threadIntervalEmail"];
            if(att != null)
                threadIntervalEmail = int.Parse(att.Value);
            else
                threadIntervalEmail = 15;
            // SMTP服务器设置
            att = attributeCollection["smtpServerConnectionLimit"];
            if(att != null)
                smtpServerConnectionLimit = short.Parse(att.Value);
            else
                smtpServerConnectionLimit = -1;
            // 版本检查
            att = attributeCollection["enableLatestVersionCheck"];
            if(att != null)
                enableLatestVersionCheck = bool.Parse(att.Value);
            // 上传文件路径
            att = attributeCollection["uploadFilesPath"];
            if(att != null)
                uploadFilesPath = att.Value;

            // 读取子节点
            foreach (XmlNode child in node.ChildNodes)
            {
                if (child.Name == "providers")
                    GetProviders(child, providers);

                if (child.Name == "extensionModules")
                    GetProviders(child, extensions);

            }
        }

        #endregion

        #region 获取配置文件节点Provider
        internal void GetProviders(XmlNode node, Hashtable table)
        {
            foreach (XmlNode provider in node.ChildNodes)
            {
                switch (provider.Name)
                {
                    case "add":
                        table.Add(provider.Attributes["name"].Value, new Provider(provider.Attributes));
                        break;

                    case "remove":
                        table.Remove(provider.Attributes["name"].Value);
                        break;

                    case "clear":
                        table.Clear();
                        break;

                }

            }

        }
        #endregion

        #region 公有属性
        // Properties
        //
        public string DefaultLanguage
        {
            get { return defaultLanguage; }
        }

        public string ForumFilesPath
        {
            get { return forumFilesPath; }
        }

        public string DefaultProvider
        {
            get { return defaultProvider; }
        }

        public Hashtable Providers
        {
            get { return providers; }
        }

        public Hashtable Extensions
        {
            get { return extensions; }
        }

        public bool IsBackgroundThreadingDisabled
        {
            get { return disableBackgroundThreads; }
        }

        public bool IsIndexingDisabled
        {
            get { return disableIndexing; }
        }

        public string PasswordEncodingFormat
        {
            get { return passwordEncodingFormat; }
        }

        public string UploadFilesPath
        {
            get { return uploadFilesPath; }
        }

        public bool IsEmailDisabled
        {
            get { return disableEmail; }
        }

        public int ThreadIntervalEmail
        {
            get { return threadIntervalEmail; }
        }

        public int ThreadIntervalStats
        {
            get { return threadIntervalStats; }
        }

        public short SmtpServerConnectionLimit
        {
            get { return smtpServerConnectionLimit; }
        }

        public bool EnableLatestVersionCheck
        {
            get { return enableLatestVersionCheck; }
        }
        #endregion
    }

    /// <summary>
    /// 数据提供者实体类
    /// </summary>
    public class Provider
    {
        #region 成员字段
        private string name;
        private string providerType;
        private ExtensionType extensionType;
        private NameValueCollection providerAttributes = new NameValueCollection();
        #endregion

        #region 构造器
        public Provider(XmlAttributeCollection attributes)
        {
            // Set the name of the provider
            //
            name = attributes["name"].Value;

            // Set the extension type
            //
            try
            {
                extensionType = (ExtensionType)Enum.Parse(typeof(ExtensionType), attributes["extensionType"].Value, true);
            }
            catch
            {
                // Occassionally get an exception on parsing the extensiontype, so set it to Unknown
                extensionType = ExtensionType.Unknown;
            }

            providerType = attributes["type"].Value;

            // Store all the attributes in the attributes bucket
            //
            foreach (XmlAttribute attribute in attributes)
            {
                if ((attribute.Name != "name") && (attribute.Name != "type"))
                    providerAttributes.Add(attribute.Name, attribute.Value);

            }

        }
        #endregion

        #region 公有属性
        public string Name
        {
            get { return name; }
        }

        public string Type
        {
            get { return providerType; }
        }

        public ExtensionType ExtensionType
        {
            get { return extensionType; }
        }


        public NameValueCollection Attributes
        {
            get { return providerAttributes; }
        }

        #endregion
    }
}
    // *********************************************************************
    //  ForumsConfigurationHandler
    //
    /// <summary>
    /// Class used by ASP.NET Configuration to load ASP.NET Forums configuration.
    /// </summary>
    /// 
    // ***********************************************************************/
    /*
    internal class ForumsConfigurationHandler : IConfigurationSectionHandler
    {
        public virtual object Create(Object parent, Object context, XmlNode node)
        {
            ForumConfiguration config = new ForumConfiguration();
            config.LoadValuesFromConfigurationXml(node);
            return config;
        }

    }
*/

这个配置文件配置了ANF的默认数据提供者、默认语言、论坛路径、是滞禁用后台线程、是滞禁止索引、是否禁止邮件、密码加密格式、线程间隔状态、邮件队列发送间隔、SMTP服务器设置、版本检查
上传文件路径、数据提供者、自定义HttpModule等。主要方法为GetConfig():

public static ForumConfiguration GetConfig() 
        {
            ForumConfiguration config = cache.Get(CacheKey) as ForumConfiguration;
            if(config == null)
            {
                string path;
                if(HttpContext.Current != null)
                    path = HttpContext.Current.Server.MapPath("~/Forums.config");
                else
                    path = Directory.GetCurrentDirectory() + Path.DirectorySeparatorChar + "Forums.config";

                XmlDocument doc = new XmlDocument();
                doc.Load(path);
                config = new ForumConfiguration(doc);
                cache.Insert(CacheKey,config,new CacheDependency(path),DateTime.MaxValue,TimeSpan.Zero,CacheItemPriority.AboveNormal,null);

                //cache.ReSetFactor(config.CacheFactor);
            }
            return config;
            
        }

在此方法中，首先从Cache缓存中获取配置信息，如配置信息还未缓存，则读敢配置文件。配置文件位于网站根目录下的Forums.config文件。读取配置文件的内容后插入缓存中以便下次使用。
Forums.config文件如下：

<?xml version="1.0" encoding="utf-8" ?> 
<Forums>
    <Core defaultLanguage="zh-CN" 
        forumFilesPath="/" 
        disableEmail="false" 
        disableIndexing="true"
        disableThreading="false" 
        threadIntervalStats="15" 
        threadIntervalEmail="15" 
        smtpServerConnectionLimit="-1"
        passwordEncodingFormat="unicode" 
        enableLatestVersionCheck="false" 
        uploadFilesPath="/Upload/"
        defaultProvider="SqlForumsProvider">
        <providers>
            <clear />
            <add name="LocalSqlForumsProvider" type="AspNetForums.Data.SqlDataProvider, AspNetForums.SqlDataProvider"
                connectionString="server=.;database=Forums;uid=sa;pwd=" databaseOwner="dbo" />
            <add name="SqlForumsProvider" type="AspNetForums.Data.SqlDataProvider, AspNetForums.SqlDataProvider"
                connectionStringName = "SiteSqlServer" databaseOwnerStringName = "SiteSqlServerOwner" />
            <add name="SqlDataProviderNonDbo" type="AspNetForums.Data.SqlDataProviderNonDbo, AspNetForums.SqlDataProviderNonDbo"
                connectionStringName = "SiteSqlServer" databaseOwnerStringName = "SiteSqlServerOwner" />
        </providers>
        <extensionModules>
            <add name="PassportAuthentication" extensionType="Security" type="Telligent.CommunityServer.Security.PassportAuthentication, Telligent.CommunityServer.SecurityModules" />
            <add name="WindowsAuthentication" extensionType="Security" type="Telligent.CommunityServer.Security.WindowsAuthentication, Telligent.CommunityServer.SecurityModules"
                allowAutoUserRegistration="true" adminWindowsGroup="Administrators" adminWindowsGroupIsSystemAdministrator="true" />
            <add name="FormsAuthentication" extensionType="Security" type="Telligent.CommunityServer.Security.FormsAuthentication, Telligent.CommunityServer.SecurityModules"
                allowAutoUserRegistration="true" userEmailAddressCookie="CSUserEmailAddress" useEncryptedEmailAddressCookie="false" />
        </extensionModules>
    </Core>
</Forums>

二、缓存

通过在类中添加private static readonly Cache cache = HttpRuntime.Cache;来实现。

三、多数据访问

ANF的数据访问基类是ForumsDataProvider类，ForumsDataProvider这个类位于AspNetForums.Components命名空间下。这是一个抽象类，你可以去实现你的SQL子类或其他子类。主要方法为两个实例化方法。
实例化方法一：

public static ForumsDataProvider Instance()
  {
   // 理论上应该出现不了null,但程序运行确实出现过.原因待查.
   if(_defaultInstance == null)
    CreateDefaultCommonProvider();
            return _defaultInstance;
  }

       
在第一个实例化方法中，使用了单例设计模式，如果默认实例为空，则创建默认实例，方法如下：

private static void CreateDefaultCommonProvider()
        {
            ForumConfiguration config = ForumConfiguration.GetConfig();
            Provider sqlForumsProvider = (Provider) config.Providers[config.DefaultProvider];
            _defaultInstance = DataProviders.CreateInstance(sqlForumsProvider) as ForumsDataProvider;
        }

首先获取配置信息，通过配置信息中的默认数据提供者来创建默认实例。

实例化方法二：

public static ForumsDataProvider Instance (Provider dataProvider) 
        {
            ForumsDataProvider fdp = cache.Get(dataProvider.Name) as ForumsDataProvider;
            if(fdp == null)
            {
                fdp = DataProviders.Invoke(dataProvider) as ForumsDataProvider;
    cache.Insert(dataProvider.Name,fdp,null,DateTime.MaxValue,TimeSpan.Zero,CacheItemPriority.AboveNormal,null);
            }
            return fdp;
        }

在第二个实例化方法中，使用了缓存，通过给定的提供者，如果缓存中有，则直接调用。如果没有，则创建。创建后插入缓存以便下次使用。

其它抽象方法为子类需要实现的真正的数据访问方法。

欢迎大家指正。