CommunityServer中的模板基类---TemplatedWebControl的研究

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

using System;
using System.ComponentModel;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using CommunityServer.Components;

namespace CommunityServer.Controls {

    /**//// <summary>
    /// The base class for ALL community server controls that must load their UI either through an external skin
    /// or via an in-page template.
    /// </summary>
    [
    ParseChildren( true ),
    PersistChildren( false ),
    ]
    public abstract class TemplatedWebControl : WebControl, INamingContainer {

        Composite Controls#region Composite Controls

        /**//// <exclude/>
        public override ControlCollection Controls {
            get {
                this.EnsureChildControls();
                return base.Controls;
            }
        }

        /**//// <exclude/>
        public override void DataBind() {
            this.EnsureChildControls();
            base.DataBind ();
        }

        #endregion

        External Skin#region External Skin

        /**//// <summary>
        /// Gets the name of the theme being used.
        /// </summary>
        protected virtual string ThemeName {
            get {
                return CSContext.Current.User.Theme;
            }
        }

        protected virtual string SkinFolder {
            get {
                return "~/Themes/" + ThemeName + "/Skins/"; //TODO Use correct skin folder
            }
        }

        private String SkinPath {
            get {
                return this.SkinFolder + ExternalSkinFileName;
            }
        }

        /**//// <summary>
        /// Gets the name of the skin file to load from
        /// </summary>
        protected virtual String ExternalSkinFileName {
            get {
                if (SkinName == null)
                    return CreateExternalSkinFileName(null);

                return SkinName;
            }
            set {
                SkinName = value;
            }
        }

        string skinName;
        public string SkinName {
            get {
                return skinName;
            }
            set {
                skinName = value;
            }
        }

        protected virtual string CreateExternalSkinFileName(string path)
        {
            return CreateExternalSkinFileName(path, "Skin-" + this.GetType().Name);
        }

        protected virtual string CreateExternalSkinFileName(string path, string name)
        {
            if(path != null && !path.EndsWith("/"))
                path = path + "/";

            return string.Format("{0}{1}.ascx",path,name);
        }


        private Boolean SkinFolderExists 
        {
            get {
                HttpContext context = HttpContext.Current;
                if ( context != null ) {
                    String folderPath = context.Server.MapPath( this.SkinFolder );
                    return System.IO.Directory.Exists( folderPath );
                }
                return true;
            }
        }

        private Boolean SkinFileExists {
            get {    
                HttpContext context = HttpContext.Current;
                if ( context != null ) {
                    String filePath = context.Server.MapPath( this.SkinPath );
                    return System.IO.File.Exists( filePath );
                }
                return true;
            }
        }

        private Boolean DefaultSkinFileExists {
            get {
                HttpContext context = HttpContext.Current;
                if ( context != null ) {
                    String filePath = context.Server.MapPath( this.DefaultSkinPath );
                    return System.IO.File.Exists( filePath );
                }
                return true;
            }
        }

        protected virtual string DefaultSkinPath {
            get {
                return "~/Themes/default/Skins/" + ExternalSkinFileName;
            }
        }

        #endregion

        Public Properties#region Public Properties

        /**//// <summary>
        /// The template used to override the default UI of the control.
        /// </summary>
        /// <remarks>
        /// All serverside controls that are in the default UI must exist and have the same ID's.
        /// </remarks>
        [
        Browsable( false ),
        DefaultValue( null ),
        Description( "TODO SkinTemplate Description" ),
        PersistenceMode( PersistenceMode.InnerProperty ),
            ]
        public ITemplate SkinTemplate {
            get {
                return _skinTemplate;
            }
            set {
                _skinTemplate = value;
                ChildControlsCreated = false;
            }
        }
        private ITemplate _skinTemplate;

        #endregion

        public override void RenderBeginTag(HtmlTextWriter writer)
        {
        }
           
        /**//// <summary>
        /// No End Span
        /// </summary>
        /// <param name="writer"></param>
        public override void RenderEndTag(HtmlTextWriter writer)
        {
            //we don't need a span tag
        }

        /**//// <exclude/>
        public override Control FindControl( string id ) {
            Control ctrl = base.FindControl( id );
            if ( ctrl == null && this.Controls.Count == 1 ) {
                ctrl = this.Controls[ 0 ].FindControl( id );
            }
            return ctrl;
        }

        /**//// <exclude/>
        protected override void CreateChildControls() {
            Controls.Clear();

            // 1) A custom theme setting is the most important
            Boolean _skinLoaded = false;
            if ( !Globals.IsNullorEmpty(ThemeName) ) {
                if ( SkinFolderExists ) {
                    if ( SkinFileExists && this.Page != null ) {
                        Control skin = this.Page.LoadControl( this.SkinPath );
                        this.Controls.Add( skin );
                        _skinLoaded = true;
                    }
                } 
            } 

            // 2) Next, look for an inline template
            if ( !_skinLoaded && SkinTemplate != null ) {
                SkinTemplate.InstantiateIn( this );
                _skinLoaded = true;
            }

            // 3) last resort is the default external skin
            if ( !_skinLoaded && this.Page != null && this.DefaultSkinFileExists ) {
                Control defaultSkin = this.Page.LoadControl( this.DefaultSkinPath );
                this.Controls.Add( defaultSkin );
                _skinLoaded = true;
            }

            // 4) If none of the skin locations were successful, throw.
            if ( !_skinLoaded ) {
                throw new CSException( CommunityServer.Components.CSExceptionType.SkinNotFound );
            }
                
            AttachChildControls();
        }

        
        /**//// <summary>
        /// Override this method to attach templated or external skin controls to local references.
        /// </summary>
        /// <remarks>
        /// This will only be called if the non-default skin is used.
        /// </remarks>
        protected abstract void AttachChildControls();

        protected override void Render(HtmlTextWriter writer)
        {
            //SourceMarker(true,writer);
            base.Render (writer);
            //SourceMarker(false,writer);
        }

        [System.Diagnostics.Conditional("DEBUG")]
        protected void SourceMarker(bool isStart, HtmlTextWriter writer)
        {
           
            if(isStart)
            {
                writer.WriteLine("<!-- Start: {0} -->", this.GetType());
                
                if(System.IO.File.Exists(this.SkinPath))
                    writer.WriteLine("<!-- Skin Path: {0} -->", this.SkinPath);
                else if(SkinTemplate != null)
                    writer.WriteLine("<!-- Inline Skin: {0} -->", true);
                else
                    writer.WriteLine("<!-- Skin Path: {0} -->", this.DefaultSkinPath);

            }
            else
                writer.WriteLine("<!-- End: {0} -->", this.GetType());
        }



    }
}

类图：



下面是该类的详细分析：

---

作用：

 /// The base class for ALL community server controls that must load their UI either through an external skin
 /// or via an in-page template.

---

CreateChildControls()方法：
功能说明：

1.如果存在自定义风格设置(custom theme setting)就首先加载该设置
2.如果条件1不满足，就检查是否存在内嵌模板，如果存在，就加载该内嵌模板。
  其中内嵌模板由调用该类的方法通过SkinTemplate公共属性来设置
3.如果条件1、2都不满足，就检查是否存在默认皮肤设置文件（DefaultSkinFileExists），如果存在，就加载该设置
4.如果条件1、2、3均不满足，就抛出异常 。

具体代码：

        /// <exclude/>
        protected override void CreateChildControls() {
            Controls.Clear();

            // 1) A custom theme setting is the most important
            Boolean _skinLoaded = false;
            if ( !Globals.IsNullorEmpty(ThemeName) ) {
                if ( SkinFolderExists ) {
                    if ( SkinFileExists && this.Page != null ) {
                        Control skin = this.Page.LoadControl( this.SkinPath );
                        this.Controls.Add( skin );
                        _skinLoaded = true;
                    }
                } 
            } 

            // 2) Next, look for an inline template
            if ( !_skinLoaded && SkinTemplate != null ) {
                SkinTemplate.InstantiateIn( this );
                _skinLoaded = true;
            }

            // 3) last resort is the default external skin
            if ( !_skinLoaded && this.Page != null && this.DefaultSkinFileExists ) {
                Control defaultSkin = this.Page.LoadControl( this.DefaultSkinPath );
                this.Controls.Add( defaultSkin );
                _skinLoaded = true;
            }

            // 4) If none of the skin locations were successful, throw.
            if ( !_skinLoaded ) {
                throw new CSException( CommunityServer.Components.CSExceptionType.SkinNotFound );
            }
                
            AttachChildControls();
        }

这里调用的AttachChildControls方法在该类中是个抽象方法：

        /// <summary>
        /// Override this method to attach templated or external skin controls to local references.
        /// </summary>
        /// <remarks>
        /// This will only be called if the non-default skin is used.
        /// </remarks>
        protected abstract void AttachChildControls();

---

SourceMarker(bool isStart, HtmlTextWriter writer)方法：
作用: 输出跟踪调试信息
备注: (1)
            

[System.Diagnostics.Conditional("DEBUG")]

        表明该方法只有在条件编译参数设置为Debug的时候才会执行
       （2）在该类中，该方法未被调用