asp.net组件设计总结

一、关于继承方面

1. 继承control类:

一般不可见html元素主要是继承control类，比如meta中的元素或者隐藏域等

2.继承webcontrol类：

一般可见元素比如<input type=text>等，为了获取更多的样式支持，减少代码量，一般直接继承webcontrol：

比如分页控件等：

http://blog.youkuaiyun.com/46539492/archive/2008/04/02/2244627.aspx

3.复合控件:

定义复合控件一般要继承INamingContainer这个接口。比如一个简单用户登陆控件

http://blog.youkuaiyun.com/46539492/archive/2008/03/14/2182934.aspx

4.数据列表控件：

比如DropDownList,CheckBoxList等控件一般继承ListControl,又因为这些控件存在数据传输或者说数据回发，则要继承IPostBackDataHandler接口。

 

5.复合列表控件

比如CheckBoxList,RadioButtonList等控件，除了继承ListControl类，IPostBackDataHandler接口外，还要实现IRepeatInfoUser接口，IRepeatInfoUser接口定义了重复项列表的列表控件实现的属性和方法，最后还因为他们是复合控件，还要继承INamingContainer接口6.数据绑定控件

 

(1)DataList

DataList类似于CheckBoxList，是重复项列表的列表控件，所以需要继承IRepeatInfoUser，也是复合控件，所以继承INamingContainer接口，此外还要继承BaseDataList类，该类用数据列表控件的基类，如DataList和DataGrid，该类提供所有数据列表控件的所有方法和属性。

(2)Repeater

Repeater比较灵活，继承control和INamingContainer接口。

(3)DataGrid

DataGrid类，和DataList类似，主要继承BaseDataList类和INamingContainer接口

(4)GridView
GridView是比较复杂的数据绑定控件，继承CompositeDataBoundControl, IPostBackContainer, IPostBackEventHandler, ICallbackContainer, ICallbackEventHandler

其中CompositeDataBoundControl表示由其他服务器控件组成的表格数据绑定控件的基类； IPostBackContainer接口定义一个方法；使控件能够获取客户端脚本选项。ICallbackContainer接口定义一个方法，使控件能够获取回调脚本；ICallbackEventHandler用于指示控件可以作为服务器的回调事件的目标。

6.导航控件

(1)TreeView控件

TreeView控件主要继承HierarchicalDataBoundControl, IPostBackEventHandler, IPostBackDataHandler, ICallbackEventHandler，其中HierarchicalDataBoundControl用作所有 ASP.NET 2.0 版数据绑定控件的基类，这些控件以分层形式显示它们的数据。因为有数据回发所以继承IPostBackDataHandler，继承IPostBackEventHandler处理回发事件，和GridView类似，ICallbackEventHandler用于指示控件可以作为服务器的回调事件的目标

(2)Menu控件

Menu主要继承HierarchicalDataBoundControl, IPostBackEventHandler, INamingContainer，因为Menu是个复合控件，继承INamingContainer接口。

二、样式相关

1. 重写TagKey

示例如下：

        重写TagKey #region 重写TagKey
        protected override HtmlTextWriterTag TagKey
        ...{
            get
            ...{
                return HtmlTextWriterTag.Table;
            }
        }
        #endregion

默认是HtmlTextWriterTag.Span,当需要其它标签时，需要重写TagKey，

比如以下代码：

 

  < table width = " 100% "  style = "  height:20px; border:solid 1px #cccccc; "  cellpadding = " 0 "  cellspacing = " 0 "   >

             < tr >

                 < td align = " right " >

                   当前第

                     < asp:Label ID = " lblCurrentPage "  runat = " server " ></ asp:Label > 页,

                    总共 < asp:Label ID = " lblRecodeCount "  runat = " server " ></ asp:Label > 条纪录,

                    共 < asp:Label ID = " lblPageCount "  runat = " server " ></ asp:Label > 页,

                     < asp:Label ID = " Label1 "  runat = " server " ></ asp:Label >

                     < asp:LinkButton ID = " lnkbtnFrist "  runat = " server "  OnClick = " lnkbtnFrist_Click " >< font face = webdings color = " red " > 9 </ font ></ asp:LinkButton >

                      < asp:LinkButton ID = " lnkbtnPre "  runat = " server "  OnClick = " lnkbtnPre_Click " >< font face = webdings color = " red " > 7 </ font ></ asp:LinkButton >

                      < asp:LinkButton ID = " lnkbtnNext "  runat = " server "  OnClick = " lnkbtnNext_Click " >< font face = webdings color = " red " > 8 </ font ></ asp:LinkButton >

                     < asp:LinkButton ID = " lnkbtnLast "  runat = " server "  OnClick = " lnkbtnLast_Click " >< font face = webdings color = " red " > : </ font ></ asp:LinkButton >

                    跳转到第 < asp:TextBox ID = " txtPageIndex "  runat = " server "  style = " width:40px; "  onkeypress = " myKeyDown(); " ></ asp:TextBox > 页 < asp:Button ID = " BtnChangePage "  runat = " server "  Text = " GO "  OnClick = " BtnChangePage_Click "   />                    

               </ td >

             </ tr >

         </ table >

这段代码要写成控件，就需要重写TaGKey，改为HtmlTextWriterTag.Table。

然后绘制控件：

 

绘制控件 #region 绘制控件
        protected override void RenderContents(HtmlTextWriter writer)
        ...{
            if (ButtonStyle != null)
            ...{
                _btnChangePage.ApplyStyle(ButtonStyle);
            }
            if (TextBoxStyle != null)
            ...{
                _txtPageIndex.ApplyStyle(TextBoxStyle);
            }
            if (LabelStyle != null)
            ...{
                _lblCurrentPage.ApplyStyle(LabelStyle);
                _lblPageCount.ApplyStyle(LabelStyle);
                _lblRecodeCount.ApplyStyle(LabelStyle);
                _lblPageSize.ApplyStyle(LabelStyle);
            }
            AddAttributesToRender(writer);
            writer.RenderBeginTag(HtmlTextWriterTag.Tr);
            writer.AddAttribute(HtmlTextWriterAttribute.Align, "right");
            writer.RenderBeginTag(HtmlTextWriterTag.Td);
            writer.Write("当前第");
            if (_lblCurrentPage != null)
                _lblCurrentPage.RenderControl(writer);
            writer.Write("页,每页");
            if (_lblPageSize != null)
            ...{
                _lblPageSize.RenderControl(writer);
            }
            writer.Write("条纪录,总共");
            if (_lblRecodeCount != null)
                _lblRecodeCount.RenderControl(writer);
            writer.Write("条纪录,共");
            if (_lblPageCount != null)
                _lblPageCount.RenderControl(writer);
            writer.Write("页&nbsp;&nbsp;[&nbsp;&nbsp;");
            if (_lnkbtnFrist != null)
            ...{
                if (PageIndex == 1) //如果是第一页，则第一页灰显，作用是避免不必要的点击造成没必要的数据传输
                ...{
                    _lnkbtnFrist.Enabled = false;
                }
                else
                ...{
                    _lnkbtnFrist.Enabled = true;
                }
                _lnkbtnFrist.RenderControl(writer);
            }
            writer.Write("&nbsp;");
            if (_lnkbtnPre != null)
            ...{
                if (PageIndex > 1) //如果当前页大于1，则上一页显示，否则灰显
                ...{
                    _lnkbtnPre.Enabled = true;
                }
                else
                ...{
                    _lnkbtnPre.Enabled = false;
                }
                _lnkbtnPre.RenderControl(writer);
            }
            writer.Write("&nbsp;");
            if (_lnkbtnNext != null)
            ...{
                if (_lblPageCount == null)
                ...{
                    _lnkbtnNext.Enabled = false;
                }
                else
                ...{
                    int pageCount = int.Parse(_lblPageCount.Text); //获取总页数
                    if (PageIndex < pageCount)//如果当前页小于总页数，则下一页显示，否则灰显
                    ...{
                        _lnkbtnNext.Enabled = true;
                    }
                    else
                    ...{
                        _lnkbtnNext.Enabled = false;
                    }
                }
                _lnkbtnNext.RenderControl(writer);
            }
            writer.Write("&nbsp;");
            if (_lnkbtnLast != null)
            ...{
                if (_lblPageCount == null)
                ...{
                    _lnkbtnLast.Enabled = false;
                }
                else
                ...{
                    int pageCount = int.Parse(_lblPageCount.Text); //获取总页数
                    if (PageIndex == pageCount)//如果当前页为最后一页，则末页灰显
                    ...{
                        _lnkbtnLast.Enabled = false;
                    }
                    else
                    ...{
                        _lnkbtnLast.Enabled = true;
                    }
                }
                _lnkbtnLast.RenderControl(writer);
            }
            writer.Write("&nbsp;&nbsp;]跳转到第");
            if (_txtPageIndex != null)
                _txtPageIndex.RenderControl(writer);
            writer.Write("页");
            if (_btnChangePage != null)
                _btnChangePage.RenderControl(writer);
            writer.RenderEndTag();
            writer.RenderEndTag();
            //base.RenderContents(writer);
        }
        #endregion
    }
}

2.重写CreateControlStyle

重写CreateControlStyle，可以根据需要应用相关的样式，比如继承Label类，并重写CreateControlStyle方法，使该控件具有表格的样式：

 

protected   override  Style CreateControlStyle()
         ... {

            return new TableStyle(ViewState);
        }

        [BrowsableAttribute( true )]
        [DescriptionAttribute( " 网格线 " )]
        [CategoryAttribute( " Appearance " )]
         public   virtual  GridLines GridLines
         ... {
            get ...{ return ((TableStyle)ControlStyle).GridLines; }
            set ...{ ((TableStyle)ControlStyle).GridLines = value; }
        }

这样该自定义的label就具有表格的样式，比如网格线。

3.继承webcontrol

通过继承webcontrol类可以获得webcontrol类很多样式，比如：

4.通过继承Style类来自定义Style

示例如下：

 

using  System;
using  System.Collections.Generic;
using  System.Text;
using  System.Web;
using  System.ComponentModel;
using  System.Web.UI.WebControls;
using  System.Web.UI;
namespace  MyLabel
... {
    public class LabelStyle:Style
    ...{
        public LabelStyle() ...{ }
        public LabelStyle(StateBag viewState) : base(viewState) ...{ }

        public virtual String ImageUrl
        ...{
            get ...{ return ViewState["imageUrl"] != null ? (string)ViewState["imageUrl"] : ""; }
            set ...{ ViewState["imageUrl"] = value; }
        }
        //判断视图状态是否为空
        internal bool IsSet(string key)
        ...{
            return ViewState[key] != null;
        }

        /**//**/
        /**//// <summary>
        /// 是否定义样式元素
        /// </summary>
        public override bool IsEmpty
        ...{
            get
            ...{
                return base.IsEmpty && !IsSet("imageUrl");
            }
        }
        public override void AddAttributesToRender(HtmlTextWriter writer, WebControl owner)
        ...{
            writer.AddStyleAttribute(HtmlTextWriterStyle.BackgroundImage, ImageUrl);


            base.AddAttributesToRender(writer, owner);
        }

    }
}

使用方法：

 

using  System;
using  System.Collections.Generic;
using  System.Text;
using  System.ComponentModel;
using  System.Web;
using  System.Web.UI;
using  System.Web.UI.WebControls;

namespace  MyLabel
... {
    public class MyLabel3:Label
    ...{
        protected override Style CreateControlStyle()
        ...{
            return new LabelStyle();//使用自定义的Style
        }

        [DefaultValue("")]
        public virtual string ImageUrl
        ...{
            get
            ...{
                return ((LabelStyle)ControlStyle).ImageUrl;
            }
            set
            ...{
                ((LabelStyle)ControlStyle).ImageUrl = value;
            }

        }
    }
}

 

三、属性相关

1.简单属性

简单属性是指属性值可以很容易转换为字符串表达式的属性，这种属性的值通常为Boolean、Byte、Char、Double、Enum、Int32、DateTime等简单数值类型，以及String类型和枚举类型。开发人员可以通过添加代码，将简单属性存储在ViewState字典中，以在回发间进行状态管理。

通常的示例如下：

 

 [Browsable( true )]
        [Category( " Appearance " )]
        [Description( " 设置单击当前行时当前行的背景色 " )]
         public   virtual  Color ClickBackGroundColor
         ... {
            get
            ...{
                return ViewState["ClickBackGroundColor"]!=null?(Color)ViewState["ClickBackGroundColor"]:Color.Empty;
            }
            set
            ...{

                ViewState["ClickBackGroundColor"] = value;
            }
        }

2.复杂属性

如果一个属性的类型是本身具有属性（称为子属性）的类，则该属性就称为复杂属性。例如，WebControl类的Font属性的类型是本身具有属性（如Bold和Name）的FontInfo类。Bold和Name是WebControl的Font属性的子属性。

复杂属性不能简单的用ViewState来进行状态管理，需要自定义视图状态，比如我前一篇文章《千万级数据分页之二---一个简单的自定义分页控件》定义的ButtonStyle,TextBoxStyle等就属于复杂属性：

 

     样式属性 #region 样式属性
        private Style _buttonStyle;
        private Style _textBoxStyle;
        private Style _linkButtonStyle;
        [
        Category("Styles"),
        DefaultValue(null),
        DesignerSerializationVisibility(
            DesignerSerializationVisibility.Content),
        PersistenceMode(PersistenceMode.InnerProperty),
        Description(
            "应用于按钮的样式")
        ]
        public virtual Style ButtonStyle
        ...{
            get
            ...{
                if (_buttonStyle == null)
                ...{
                    _buttonStyle = new Style();
                    if (IsTrackingViewState)
                    ...{
                        ((IStateManager)_buttonStyle).TrackViewState();
                    }
                }
                return _buttonStyle;
            }
        }
        [
       Category("Styles"),
       DefaultValue(null),
       DesignerSerializationVisibility(
           DesignerSerializationVisibility.Content),
       PersistenceMode(PersistenceMode.InnerProperty),
       Description(
           "应用于链接按钮的样式")
       ]
        public virtual Style LinkButtonStyle
        ...{
            get
            ...{
                if (_linkButtonStyle == null)
                ...{
                    _linkButtonStyle = new Style();
                    if (IsTrackingViewState)
                    ...{
                        ((IStateManager)_linkButtonStyle).TrackViewState();
                    }
                }
                return _linkButtonStyle;
            }
        }

        [
        Category("Styles"),
        DefaultValue(null),
        DesignerSerializationVisibility(
            DesignerSerializationVisibility.Content),
        PersistenceMode(PersistenceMode.InnerProperty),
        Description(
            "应用于文本框的样式")
        ]
        public virtual Style TextBoxStyle
        ...{
            get
            ...{
                if (_textBoxStyle == null)
                ...{
                    _textBoxStyle = new Style();
                    if (IsTrackingViewState)
                    ...{
                        ((IStateManager)_textBoxStyle).TrackViewState();
                    }
                }
                return _textBoxStyle;
            }
        }
        private Style _labelStyle;
        [
        Category("Styles"),
        DefaultValue(null),
        DesignerSerializationVisibility(
            DesignerSerializationVisibility.Content),
        PersistenceMode(PersistenceMode.InnerProperty),
        Description(
            "应用于标签的样式")
        ]
        public virtual Style LabelStyle
        ...{
            get
            ...{
                if (_labelStyle == null)
                ...{
                    _labelStyle = new Style();
                    if (IsTrackingViewState)
                    ...{
                        ((IStateManager)_labelStyle).TrackViewState();
                    }
                }
                return _labelStyle;
            }
        }
        #endregion

         自定义视图状态 #region 自定义视图状态
        protected override void LoadViewState(object savedState)
        ...{
            if (savedState == null)
            ...{
                base.LoadViewState(null);
                return;
            }
            else
            ...{
                Triplet t = savedState as Triplet;

                if (t != null)
                ...{
                    base.LoadViewState(baseState);

                    if ((t.Second) != null)
                    ...{
                        ((IStateManager)ButtonStyle).LoadViewState(buttonStyleState);
                    }

                    if ((t.Third) != null)
                    ...{
                        ((IStateManager)TextBoxStyle).LoadViewState(textBoxStyleState);
                    }
                    if (labelStyleState != null)
                    ...{
                        ((IStateManager)(_labelStyle)).LoadViewState(labelStyleState);
                    }
                    if (linkButtonStyleState != null)
                    ...{
                        ((IStateManager)(_linkButtonStyle)).LoadViewState(linkButtonStyleState);
                    }
                }
                else
                ...{
                    throw new ArgumentException("Invalid view state .");
                }
            }
        }

        protected override object SaveViewState()
        ...{
            baseState = base.SaveViewState();
            buttonStyleState = null;
            textBoxStyleState = null;
            labelStyleState = null;
            linkButtonStyleState = null;
            if (_buttonStyle != null)
            ...{
                buttonStyleState =
                    ((IStateManager)_buttonStyle).SaveViewState();
            }

            if (_textBoxStyle != null)
            ...{
                textBoxStyleState =
                    ((IStateManager)_textBoxStyle).SaveViewState();
            }
            if (_labelStyle != null)
            ...{
                labelStyleState = ((IStateManager)_labelStyle).SaveViewState();
            }
            if (_linkButtonStyle != null)
            ...{
                linkButtonStyleState = ((IStateManager)_linkButtonStyle).SaveViewState();
            }
            return new Triplet(baseState,
                buttonStyleState, textBoxStyleState);

        }

        protected override void TrackViewState()
        ...{
            base.TrackViewState();
            if (_buttonStyle != null)
            ...{
                ((IStateManager)_buttonStyle).TrackViewState();
            }
            if (_textBoxStyle != null)
            ...{
                ((IStateManager)_textBoxStyle).TrackViewState();
            }
            if (_labelStyle != null)
            ...{
                ((IStateManager)_labelStyle).TrackViewState();
            }
            if (_linkButtonStyle != null)
            ...{
                ((IStateManager)_linkButtonStyle).TrackViewState();
            }
        }
        #endregion