asp.net組件設計總結

一、關於繼承方面

1. 繼承control類:

一般不可見html元素主要是繼承control類，比如meta中的元素或者隱藏域等

2.繼承webcontrol類：

一般可見元素比如<input type=text>等，爲了獲取更多的樣式支持，減少代碼量，一般直接繼承webcontrol：

比如分頁控件等：

http://blog.csdn.net/46539492/archive/2008/04/02/2244627.aspx

3.複合控件:

定義複合控件一般要繼承INamingContainer這個接口。比如一個簡單用戶登陸控件

http://blog.csdn.net/46539492/archive/2008/03/14/2182934.aspx

4.數據列表控件：

比如DropDownList,CheckBoxList等控件一般繼承ListControl,又因爲這些控件存在數據傳輸或者說數據回發，則要繼承IPostBackDataHandler接口。

 

5.複合列表控件

比如CheckBoxList,RadioButtonList等控件，除了繼承ListControl類，IPostBackDataHandler接口外，還要實現IRepeatInfoUser接口，IRepeatInfoUser接口定義了重複項列表的列表控件實現的屬性和方法，最後還因爲他們是複合控件，還要繼承INamingContainer接口6.數據綁定控件

 

(1)DataList

DataList類似於CheckBoxList，是重複項列表的列表控件，所以需要繼承IRepeatInfoUser，也是複合控件，所以繼承INamingContainer接口，此外還要繼承BaseDataList類，該類用數據列表控件的基類，如DataList和DataGrid，該類提供所有數據列表控件的所有方法和屬性。

(2)Repeater

Repeater比較靈活，繼承control和INamingContainer接口。

(3)DataGrid

DataGrid類，和DataList類似，主要繼承BaseDataList類和INamingContainer接口

(4)GridView
GridView是比較複雜的數據綁定控件，繼承CompositeDataBoundControl, IPostBackContainer, IPostBackEventHandler, ICallbackContainer, ICallbackEventHandler

其中CompositeDataBoundControl表示由其他服務器控件組成的表格數據綁定控件的基類； IPostBackContainer接口定義一個方法；使控件能夠獲取客戶端腳本選項。ICallbackContainer接口定義一個方法，使控件能夠獲取回調腳本；ICallbackEventHandler用於指示控件可以作爲服務器的回調事件的目標。

6.導航控件

(1)TreeView控件

TreeView控件主要繼承HierarchicalDataBoundControl, IPostBackEventHandler, IPostBackDataHandler, ICallbackEventHandler，其中HierarchicalDataBoundControl用作所有 ASP.NET 2.0 版數據綁定控件的基類，這些控件以分層形式顯示它們的數據。因爲有數據回發所以繼承IPostBackDataHandler，繼承IPostBackEventHandler處理回發事件，和GridView類似，ICallbackEventHandler用於指示控件可以作爲服務器的回調事件的目標

(2)Menu控件

Menu主要繼承HierarchicalDataBoundControl, IPostBackEventHandler, INamingContainer，因爲Menu是個複合控件，繼承INamingContainer接口。

二、樣式相關

1. 重寫TagKey

示例如下：

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

默認是HtmlTextWriterTag.Span,當需要其它標籤時，需要重寫TagKey，

比如以下代碼：

 

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

            <tr>

                <td align="right">

                   當前第

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

                    總共<asp:Label ID="lblRecodeCount" runat="server"></asp:Label>條紀錄,

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

                    <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>

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

              </td>

            </tr>

        </table>

這段代碼要寫成控件，就需要重寫TaGKey，改爲HtmlTextWriterTag.Table。

然後繪製控件：

 

繪製控件#region 繪製控件
        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("當前第");
            if (_lblCurrentPage != null)
                _lblCurrentPage.RenderControl(writer);
            writer.Write("頁,每頁");
            if (_lblPageSize != null)
            ...{
                _lblPageSize.RenderControl(writer);
            }
            writer.Write("條紀錄,總共");
            if (_lblRecodeCount != null)
                _lblRecodeCount.RenderControl(writer);
            writer.Write("條紀錄,共");
            if (_lblPageCount != null)
                _lblPageCount.RenderControl(writer);
            writer.Write("頁&nbsp;&nbsp;[&nbsp;&nbsp;");
            if (_lnkbtnFrist != null)
            ...{
                if (PageIndex == 1) //如果是第一頁，則第一頁灰顯，作用是避免不必要的點擊造成沒必要的數據傳輸
                ...{
                    _lnkbtnFrist.Enabled = false;
                }
                else
                ...{
                    _lnkbtnFrist.Enabled = true;
                }
                _lnkbtnFrist.RenderControl(writer);
            }
            writer.Write("&nbsp;");
            if (_lnkbtnPre != null)
            ...{
                if (PageIndex > 1) //如果當前頁大於1，則上一頁顯示，否則灰顯
                ...{
                    _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); //獲取總頁數
                    if (PageIndex < pageCount)//如果當前頁小於總頁數，則下一頁顯示，否則灰顯
                    ...{
                        _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); //獲取總頁數
                    if (PageIndex == pageCount)//如果當前頁爲最後一頁，則末頁灰顯
                    ...{
                        _lnkbtnLast.Enabled = false;
                    }
                    else
                    ...{
                        _lnkbtnLast.Enabled = true;
                    }
                }
                _lnkbtnLast.RenderControl(writer);
            }
            writer.Write("&nbsp;&nbsp;]跳轉到第");
            if (_txtPageIndex != null)
                _txtPageIndex.RenderControl(writer);
            writer.Write("頁");
            if (_btnChangePage != null)
                _btnChangePage.RenderControl(writer);
            writer.RenderEndTag();
            writer.RenderEndTag();
            //base.RenderContents(writer);
        }
        #endregion
    }
}

2.重寫CreateControlStyle

重寫CreateControlStyle，可以根據需要應用相關的樣式，比如繼承Label類，並重寫CreateControlStyle方法，使該控件具有表格的樣式：

 

protected override Style CreateControlStyle()
        ...{

            return new TableStyle(ViewState);
        }

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

這樣該自定義的label就具有表格的樣式，比如網格線。

3.繼承webcontrol

通過繼承webcontrol類可以獲得webcontrol類很多樣式，比如：

4.通過繼承Style類來自定義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; }
        }
        //判斷視圖狀態是否爲空
        internal bool IsSet(string key)
        ...{
            return ViewState[key] != null;
        }

        /**//**/
        /**//// <summary>
        /// 是否定義樣式元素
        /// </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();//使用自定義的Style
        }

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

        }
    }
}

 

三、屬性相關

1.簡單屬性

簡單屬性是指屬性值可以很容易轉換爲字符串表達式的屬性，這種屬性的值通常爲Boolean、Byte、Char、Double、Enum、Int32、DateTime等簡單數值類型，以及String類型和枚舉類型。開發人員可以通過添加代碼，將簡單屬性存儲在ViewState字典中，以在回發間進行狀態管理。

通常的示例如下：

 

 [Browsable(true)]
        [Category("Appearance")]
        [Description("設置單擊當前行時當前行的背景色")]
        public virtual Color ClickBackGroundColor
        ...{
            get
            ...{
                return ViewState["ClickBackGroundColor"]!=null?(Color)ViewState["ClickBackGroundColor"]:Color.Empty;
            }
            set
            ...{

                ViewState["ClickBackGroundColor"] = value;
            }
        }

2.複雜屬性

如果一個屬性的類型是本身具有屬性（稱爲子屬性）的類，則該屬性就稱爲複雜屬性。例如，WebControl類的Font屬性的類型是本身具有屬性（如Bold和Name）的FontInfo類。Bold和Name是WebControl的Font屬性的子屬性。

複雜屬性不能簡單的用ViewState來進行狀態管理，需要自定義視圖狀態，比如我前一篇文章《千萬級數據分頁之二---一個簡單的自定義分頁控件》定義的ButtonStyle,TextBoxStyle等就屬於複雜屬性：

 

    樣式屬性#region 樣式屬性
        private Style _buttonStyle;
        private Style _textBoxStyle;
        private Style _linkButtonStyle;
        [
        Category("Styles"),
        DefaultValue(null),
        DesignerSerializationVisibility(
            DesignerSerializationVisibility.Content),
        PersistenceMode(PersistenceMode.InnerProperty),
        Description(
            "應用於按鈕的樣式")
        ]
        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(
           "應用於鏈接按鈕的樣式")
       ]
        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(
            "應用於文本框的樣式")
        ]
        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(
            "應用於標籤的樣式")
        ]
        public virtual Style LabelStyle
        ...{
            get
            ...{
                if (_labelStyle == null)
                ...{
                    _labelStyle = new Style();
                    if (IsTrackingViewState)
                    ...{
                        ((IStateManager)_labelStyle).TrackViewState();
                    }
                }
                return _labelStyle;
            }
        }
        #endregion

        自定義視圖狀態#region 自定義視圖狀態
        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