CommunityServer中的Provider模式的应用

CommunityServer中的Provider模式的应用

Provider的优势:
不关心具体实现
支持多数据库
方便文档描述交流
有利于团队协作分工

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下图是程序的结构。

                                 图1

下面给出具体的程序示例：

Blogs\Controls\Admin\BlogFeedbackAdmin.cs文件中的一个方法：

        /// <exclude />
        public override void DataBind() 
        {
            base.DataBind ();

            this.FeedbackList.DataKeyField = "PostID";
            Int32 totalRecords;
            this.FeedbackList.DataSource = BlogFeedback.GetFeedback( this.CurrentWeblog.SectionID, GridPager.PageIndex, this.GridPager.PageSize, out totalRecords );
            //this.FeedbackList.VirtualItemCount = totalRecords;
            this.GridPager.TotalRecords = totalRecords;
            this.FeedbackList.DataBind();
        }

这里用到了一个 BlogFeedback类，这个类的代码在CommunityServer.Blogs.Components的BlogFeedback.cs文件中：

 

 

 

BlogFeedback.cs的源代码
//------------------------------------------------------------------------------
// <copyright company="Telligent Systems">
//     Copyright (c) Telligent Systems Corporation.  All rights reserved.
// </copyright> 
//------------------------------------------------------------------------------

using System;
using System.Collections;

using CommunityServer.Components;

namespace CommunityServer.Blogs.Components 
{
    
    /// <summary>
    /// Manages the feedback that a blog post recieves.
    /// </summary>
    public sealed class BlogFeedback 
    {
        private BlogFeedback() 
        {
            // sealed static class
        }

        /// <summary>
        /// Deletes blog feedback by postIDs
        /// </summary>
        public static void DeleteFeedback( Int32 userID, Int32 sectionID, Int32[] postIDs ) 
        {
            foreach( Int32 postID in postIDs ) 
            {
                WeblogPosts.Delete(sectionID, postID, BlogPostType.Comment, userID);
            }
            
        }

        /// <summary>
        /// Sets the given feedback items to moderated
        /// </summary>
        public static void ModerateFeedback( Int32 userID, Int32 weblogID, Int32[] postIDs ) 
        {
            foreach( Int32 postID in postIDs ) 
            {
                WeblogPost p = WeblogPosts.GetPost(postID, false, false, true );
                if(weblogID == p.SectionID &&  p.IsApproved ) 
                {
                    p.IsApproved = false;
                    WeblogPosts.Update(p, userID );
                }
            }
        }

        /// <summary>
        /// Sets the given feedback items to approved
        /// </summary>
        public static void ApproveFeedback( Int32 userID, Int32 weblogID, Int32[] postIDs ) 
        {
            foreach( Int32 postID in postIDs ) 
            {
                WeblogPost p = WeblogPosts.GetPost( postID, false, false, true );
                if(weblogID == p.SectionID && !p.IsApproved ) 
                {
                    p.IsApproved = true;
                    WeblogPosts.Update( p, userID );
                }
            }
        }

        /// <summary>
        /// Gets the feedback items for the given Weblog
        /// </summary>
        /// <returns>Returns an ArrayList of FeedBackItem objects.</returns>
        public static ArrayList GetFeedback( Int32 weblogID ) 
        {
            int outRecords;
            return GetFeedback( weblogID,0,0, out outRecords);
        }

        /// <summary>
        /// Gets a paged set of feedback items for the given weblogs
        /// </summary>
        /// <returns>Returns an ArrayList of FeedBackItem objects.</returns>
        public static ArrayList GetFeedback( Int32 blogId, Int32 pageIndex, Int32 pageSize, out Int32 totalRecords ) 
        {
            WeblogDataProvider wdp = WeblogDataProvider.Instance();
            return wdp.GetFeedback( blogId,pageIndex, pageSize, out totalRecords);
        }
    }
}

 

 

注意此文件的

 

        /// <summary>

        /// Gets a paged set of feedback items for the given weblogs

        /// </summary>

        /// <returns>Returns an ArrayList of FeedBackItem objects.</returns>

        public static ArrayList GetFeedback( Int32 blogId, Int32 pageIndex, Int32 pageSize, out Int32 totalRecords ) 

        {

            WeblogDataProvider wdp = WeblogDataProvider.Instance();

            return wdp.GetFeedback( blogId,pageIndex, pageSize, out totalRecords);

        }

 

 
以上部分对应图1的Components

---

在这个文件中的WeblogDataProvider类就是DataProvider抽象类，下面看看这个类的类图：

下面是这个类的源代码：

 

//------------------------------------------------------------------------------
// <copyright company="Telligent Systems">
//     Copyright (c) Telligent Systems Corporation.  All rights reserved.
// </copyright> 
//------------------------------------------------------------------------------

using System;
using System.Collections;
using System.Data;
using System.IO;
using System.Xml;
using CommunityServer.Components;
using CommunityServer.Configuration;

namespace CommunityServer.Blogs.Components
{
    /**//// <summary>
    /// Summary description for WeblogDataProvider.
    /// </summary>
    public abstract class WeblogDataProvider
    {
        public static readonly string WeblogDataProviderName = "WeblogDataProvider";

        Search#region Search
        public abstract SearchResultSet GetSearchResults(SearchQuery query, SearchTerms terms);
        public abstract PostSet SearchReindexPosts (int setsize, int settingsID);
        #endregion

        Instance#region Instance

        private static WeblogDataProvider _defaultInstance = null;

        static WeblogDataProvider()
        {
            CreateDefaultCommonProvider();
        }

        /**//// <summary>
        /// Returns an instance of the user-specified data provider class.
        /// </summary>
        /// <returns>An instance of the user-specified data provider class.  This class must inherit the
        /// CommonDataProvider interface.</returns>
        public static WeblogDataProvider Instance() 
        {
            return _defaultInstance;
        }

        public static WeblogDataProvider Instance (Provider dataProvider) 
        {
            WeblogDataProvider fdp = CSCache.Get(dataProvider.Name) as WeblogDataProvider;
            if(fdp == null)
            {
                fdp = DataProviders.Invoke(dataProvider) as WeblogDataProvider;
                CSCache.Max(dataProvider.Name,fdp);
            }
            return fdp;
        }

        /**//// <summary>
        /// Creates the Default CommonDataProvider
        /// </summary>
        private static void CreateDefaultCommonProvider()
        {
            // Get the names of the providers
            //
            CSConfiguration config = CSConfiguration.GetConfig();

            // Read the configuration specific information
            // for this provider
            //
            Provider sqlForumsProvider = (Provider) config.Providers[WeblogDataProviderName];

            // Read the connection string for this provider
            //
            
            _defaultInstance = DataProviders.CreateInstance(sqlForumsProvider) as WeblogDataProvider;
        }
        
        #endregion

        Base Methods#region Base Methods

        Get Posts#region Get Posts
        public abstract WeblogPost GetWeblogPost(int postID, bool includeCategories, bool isApproved);
        public abstract ThreadSet GetBlogThreads(BlogThreadQuery query);
        public abstract PostSet GetPosts(BlogPostQuery query);
        public abstract PostSet GetThreadsTrackedByUser(int SectionID, int UserID);
        #endregion

        Posts#region Posts
        public abstract BlogPostResults AddPost(WeblogPost post, User user, out int PostID);
        public abstract BlogPostResults UpdatePost(WeblogPost post, int editedBy);
        public abstract void DeletePost(int sectionID, int postID, int userID, BlogPostType blogPostType);
        #endregion

        GetBlogs#region GetBlogs
        public abstract Hashtable GetWeblogs();
        #endregion

        Permissions#region Permissions
        public abstract ArrayList GetBlogPermissions(int weblogID);
        #endregion

        Blog Feedback#region Blog Feedback

        public abstract ArrayList GetFeedback( Int32 forumID, Int32 pageIndex, Int32 pageSize, out Int32 totalRecords );

        #endregion

        public abstract ArrayList GetPostsByMonths(int BlogID);
        public abstract Hashtable GetPostsByMonth(int BlogID, DateTime Month);

        public abstract void UpdateRecentContent(int SettingsID);
        public abstract void WeblogPostToForumPost(int postID, int forumID, int SettingsID);

        #endregion

        Helpers#region Helpers

        public static object ConvertCategoriesToXML(string[] Categories)
        {
            if(Categories == null || Categories.Length == 0)
                return DBNull.Value;

            StringWriter sw = new StringWriter();
            XmlTextWriter writer = new XmlTextWriter(sw);
            writer.WriteStartElement("Categories");
            foreach (string category in Categories)
            {
                writer.WriteElementString("Category", category);
            }
            writer.Close();
            return sw.ToString();
        }

        #endregion

        Populate#region Populate

        Weblogs#region Weblogs

        /**//// <summary>
        /// Populates an existing Weblog object
        /// </summary>
        public static void PopulateWeblogData(IDataReader dr, Weblog w)
        {
            CommonDataProvider.PopulateSectionFromIDataReader(dr,w);

            w.MostRecentPostName = dr["MostRecentPostName"] as string;

            w.MostRecentArticleID = (int)dr["MostRecentArticleID"];
            w.MostRecentArticleDate = (DateTime)dr["MostRecentArticleDate"];
            w.MostRecentArticleAuthor = dr["MostRecentArticleAuthor"] as string;
            w.MostRecentArticleAuthorID = (int)dr["MostRecentArticleAuthorID"];
            w.MostRecentArticleName = dr["MostRecentArticleName"] as string;
           
            w.PostCount = (int)dr["PostCount"];
            w.ArticleCount = (int)dr["ArticleCount"];
            w.TrackbackCount = (int)dr["TrackbackCount"];
            w.CommentCount = (int)dr["CommentCount"];
        }

        #endregion


        public static WeblogPost PopulateWeblogPostContentFromIDataReader(IDataReader reader) 
        {
            //Is this all of the data we need?
            WeblogPost post = new WeblogPost();


            post.SectionID =                (int) reader["SectionID"];
            post.PostID =                    (int) reader["PostID"];
            post.Replies =                (int) reader["Replies"];
            post.Views =                  (int) reader["TotalViews"];
            post.AggViews =                  (int) reader["AggViews"];
            post.ThreadID =               (int) reader["ThreadID"];
            post.Subject =                (string) reader["Subject"];
            post.Body =                   (string) reader["Body"];
            post.Username =               (string) reader["Username"];
            post.AuthorID =                  (int) reader["UserID"];
            post.PostDate =               (DateTime) reader["PostDate"];
            post.BloggerTime =               (DateTime) reader["BloggerTime"];
            post.ThreadDate =             (DateTime) reader["ThreadDate"];
            post.IsLocked =               (bool) reader["IsLocked"];
            post.IsApproved =             (bool) reader["IsApproved"];
            post.FormattedBody =           reader["FormattedBody"] as string;
            post.ThreadID = (int)reader["ThreadID"];

            post.PostLevel =        (int) reader["PostLevel"];
            post.ParentID = (int) reader["ParentID"];

            post.PostConfig =              (BlogPostConfig) (int)reader["PostConfig"];
            post.BlogPostType =            (BlogPostType) (byte)reader["BlogPostType"];

            post.TitleUrl =                reader["TitleUrl"] as string;
            post.Excerpt =                 reader["Excerpt"] as string;
            post.Name =                    reader["PostName"] as string;

            post.RatingSum = (int)reader["RatingSum"];
            post.TotalRatings = (int)reader["TotalRatings"];

            return post;
        }

        public static WeblogPost PopulateWeblogPostContentFromDataRow(DataRow dr, DataRelation relationShip) 
        {
            //Is this all of the data we need?
            WeblogPost post = new WeblogPost();


            post.SectionID =                (int) dr["SectionID"];
            post.PostID =                    (int) dr["PostID"];
            post.Replies =                (int) dr["Replies"];
            post.Views =                  (int) dr["TotalViews"];
            post.AggViews =                  (int) dr["AggViews"];
            post.ThreadID =               (int) dr["ThreadID"];
            post.Subject =                (string) dr["Subject"];
            post.Body =                   (string) dr["Body"];
            post.Username =               (string) dr["Username"];
            post.AuthorID =                  (int) dr["UserID"];
            post.PostDate =               (DateTime) dr["PostDate"];
            post.BloggerTime =               (DateTime) dr["BloggerTime"];
            post.ThreadDate =             (DateTime) dr["ThreadDate"];
            post.IsLocked =               (bool) dr["IsLocked"];
            post.EmoticonID =             (int) dr["ThreadEmoticonID"];
            post.FormattedBody =           dr["FormattedBody"] as string;

            post.IsApproved =             (bool) dr["IsApproved"];


            post.PostLevel =        (int) dr["PostLevel"];
            post.ParentID = (int) dr["ParentID"];

            post.PostConfig =              (BlogPostConfig) (int)dr["PostConfig"];
            post.BlogPostType =             (BlogPostType) (byte)dr["BlogPostType"];

            post.TitleUrl =                dr["TitleUrl"] as string;
            post.Excerpt =                 dr["Excerpt"] as string;
            post.Name =                    dr["PostName"] as string;

            post.RatingSum = (int)dr["RatingSum"];
            post.TotalRatings = (int)dr["TotalRatings"];

            DataRow[] categories = dr.GetChildRows(relationShip);
            if(categories != null && categories.Length > 0)
            {
                post.Categories = new string[categories.Length];
                for(int i = 0; i<categories.Length; i++)
                {
                    post.Categories[i] = categories[i]["Name"] as string;
                }
            }

            return post;
        }


        public static WeblogPost PopulateWeblogEntryFromIDataReader(IDataReader reader) 
        {
            WeblogPost entry = PopulateWeblogPostContentFromIDataReader(reader);
            SerializerData data = CommonDataProvider.PopulateSerializerDataIDataReader(reader, SerializationType.Post);
            entry.SetSerializerData(data);

            return entry;


//            CommonDataProvider.PopulatePostFromIDataReader(reader,entry);
//
//            entry.PostConfig = (BlogPostConfig) (int)reader["PostConfig"];
//            entry.BlogPostType = (BlogPostType) (byte)reader["BlogPostType"];
//
//            entry.BloggerTime = (DateTime) reader["BloggerTime"];
//
//            entry.TitleUrl = reader["TitleUrl"] as string;
//            entry.Excerpt = reader["Excerpt"] as string;
//            entry.Name = reader["PostName"] as string;
//
//            entry.RatingSum = (int)reader["RatingSum"];
//            entry.TotalRatings = (int)reader["TotalRatings"];
        }



        #endregion

    }
}

 

 

可以看到，这个类是抽象类，类中除了构造函数和Instance方法以及画实现的方法以外，其余的都是抽象方法。构造函数和

Instance方法的作用已经在CommunityServerBlogs/BlogFeedback.cs文件分析中论述过。

以上部分对应图1中的Data Provider APIs部分

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DataProvider API的实现类：CommunityServer.Data中的WeblogSqlDataProvider.cs文件：

 

 

下面看看其中的一个具体的方法：

        /// <summary>
        /// Returns blog comments/trackbacks
        /// </summary>
        public override ArrayList GetFeedback(int forumID, int pageIndex, int pageSize, out int totalRecords)
        {
            ArrayList feedback = new ArrayList();

            using ( SqlConnection cn = GetSqlConnection() )
            using ( SqlCommand cmd = new SqlCommand( databaseOwner + ".cs_weblog_Feedback_Get", cn ) ) 
            {
                cmd.CommandType = CommandType.StoredProcedure;

                cmd.Parameters.Add("@SectionID", SqlDbType.Int).Value = forumID;
                cmd.Parameters.Add(this.SettingsIDParameter());
                cmd.Parameters.Add("@TotalRecords", SqlDbType.Int ).Direction = ParameterDirection.Output;
                if ( pageSize > 0 ) 
                {
                    cmd.Parameters.Add( "@UsePaging", SqlDbType.Bit ).Value = true;
                    cmd.Parameters.Add( "@PageSize", SqlDbType.Int ).Value = pageSize;
                    cmd.Parameters.Add( "@PageIndex", SqlDbType.Int ).Value = pageIndex;
                }
                
                cn.Open();
                using(SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection))
                {

                    // PostID, PostAuthor, Subject, PostDate, IsApproved, PostName, TitleUrl
                    while ( dr.Read() ) 
                    {
                        BlogFeedbackItem item = new BlogFeedbackItem();
                    
                        item.PostID = (Int32)dr[ "PostID" ];
                        item.PostAuthor = (String)dr[ "PostAuthor" ];
                        item.Subject = (String)dr[ "Subject" ];
                        item.IsApproved = (Boolean)dr[ "IsApproved" ];
                        item.TitleUrl = dr[ "TitleUrl" ] as String;
                        item.PostDate = (DateTime)dr[ "PostDate" ];
                        item.Body = dr[ "Body" ] as String;

                        feedback.Add( item );
                    }

                    dr.Close();
                }
                cn.Close();
                totalRecords = (Int32)cmd.Parameters[ "@TotalRecords" ].Value;

               
            }

            return feedback;
        }

 

相关方法：

 

        protected SqlConnection GetSqlConnection () 
        {

            try 
            {
                return new SqlConnection(ConnectionString);
            } 
            catch 
            {
                throw new CSException(CSExceptionType.DataProvider, "SQL Connection String is invalid.");
            }

        }

 
以上部分对应图1中的Data Provider APIs

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可以看到，每次执行GetFeedback方法的时候，都打开一个新的数据库连接，然后操作数据库。操作完成后关闭数据库连接。（我想这样可能产生一个问题，就是如果在线人数很多的时候，就会有很多的数据库连接，这样可能会导致程序运行缓慢，是否可以采用Singleton模式的变种来控制数据库连接的数量？）

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参考资料：CommunityServer架构分析，作者：宝玉(http://blog.joycode.com/dotey;http://www.communityserver.cn  )