asp.net控件开发基础(5)

骑猪看日落 2022-05-27 13:55 160阅读 0赞

简单的讲了从WebControl继承的控件(好象我讲的都是简单的,嘿嘿).本次讲的更简单,主题是是属性,只当分享经验,希望对大家有帮助  
  
我们根据属性的不同表现形式,把其区分为简单属性和复杂属性  
  
下面来看下属性的表现形式  
  
简单属性表现形式如下,大家都很熟悉

![None.gif][] < asp:TextBox ID ="TextBox1" Text ="textbox控件" runat ="server" ></ asp:TextBox >

属性中含有子属性,称之为复杂对象,如Font属性  
复杂属性的表现形式如下,  
  
(1)连字符的表现形式

![None.gif][] < asp:TextBox ID ="TextBox1" Text ="textbox控件" runat ="server" Font-Bold ="True" ></ asp:TextBox >

(2)内镶属性的表现形式，如定义样式

![None.gif][] < asp:DataList ID ="DataList1" runat ="server" > 
![None.gif][] < SelectedItemStyle /> 
![None.gif][] < EditItemStyle /> 
![None.gif][] </ asp:DataList >

(3)内镶集合属性的表现形式，如DropDownList (先不介绍,大家可看MSDN)

![None.gif][] < asp:DropDownList ID ="DropDownList1" runat ="server" > 
![None.gif][] < asp:ListItem > x </ asp:ListItem > 
![None.gif][] < asp:ListItem > xx </ asp:ListItem > 
![None.gif][] < asp:ListItem > xxx </ asp:ListItem > 
![None.gif][] </ asp:DropDownList >

下面得好好看  
  
1,复杂属性基本使用方法  
  
请看我是怎么做的,关于下面看到了一些 元数据 ,如果你不熟悉,请参考MSDN.  
  
下面一段代码记录一个custom的信息.  
  
1.1 定义枚举

![None.gif][] using System; 
![None.gif][] 
![None.gif][] namespace CustomComponents 
![ExpandedBlockStart.gif][] \{ 
![ExpandedSubBlockStart.gif][] /// <summary> 
![InBlock.gif][] /// 职业 
![ExpandedSubBlockEnd.gif][] /// </summary> 
![InBlock.gif][] public enum Metier 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] 教师,程序员,作家 
![ExpandedSubBlockEnd.gif][] \} 
![ExpandedBlockEnd.gif][]\}

1.2定义复杂属性

![None.gif][] using System; 
![None.gif][] using System.ComponentModel; 
![None.gif][] 
![None.gif][] namespace CustomComponents 
![ExpandedBlockStart.gif][] \{ 
![InBlock.gif][] 
![InBlock.gif][] 
![ExpandedSubBlockStart.gif][] /// <summary> 
![InBlock.gif][] /// 地址集合 
![ExpandedSubBlockEnd.gif][] /// </summary> 
![InBlock.gif][] public class Address 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] private String street = null ; 
![InBlock.gif][] private String city = null ; 
![InBlock.gif][] private String state = null ; 
![InBlock.gif][] private String zip = null ; 
![InBlock.gif][] 
![InBlock.gif][] public String Street 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] get 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] return street; 
![ExpandedSubBlockEnd.gif][] \} 
![InBlock.gif][] set 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] street = value; 
![ExpandedSubBlockEnd.gif][] \} 
![ExpandedSubBlockEnd.gif][] \} 
![InBlock.gif][] 
![InBlock.gif][] 
![InBlock.gif][] public String City 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] get 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] return city; 
![ExpandedSubBlockEnd.gif][] \} 
![InBlock.gif][] set 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] city = value; 
![ExpandedSubBlockEnd.gif][] \} 
![ExpandedSubBlockEnd.gif][] \} 
![InBlock.gif][] 
![InBlock.gif][] public String State 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] get 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] return state; 
![ExpandedSubBlockEnd.gif][] \} 
![InBlock.gif][] set 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] state = value; 
![ExpandedSubBlockEnd.gif][] \} 
![ExpandedSubBlockEnd.gif][] \} 
![InBlock.gif][] 
![InBlock.gif][] public String Zip 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] get 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] return zip; 
![ExpandedSubBlockEnd.gif][] \} 
![InBlock.gif][] set 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] zip = value; 
![ExpandedSubBlockEnd.gif][] \} 
![ExpandedSubBlockEnd.gif][] \} 
![ExpandedSubBlockEnd.gif][] \} 
![ExpandedBlockEnd.gif][]\}

1.3 呈现控件

![ExpandedBlockStart.gif][] 
![None.gif][] using System; 
![None.gif][] using System.ComponentModel; 
![None.gif][] using System.Web; 
![None.gif][] using System.Web.UI; 
![None.gif][] 
![None.gif][] namespace CustomComponents 
![ExpandedBlockStart.gif][] \{ 
![InBlock.gif][] public class Custom: Control 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] private String name = null ; 
![InBlock.gif][] Address address = new Address(); 
![InBlock.gif][] private Metier metier; 
![InBlock.gif][] private int age = 0 ; 
![InBlock.gif][] 
![ExpandedSubBlockStart.gif][] \#region 属性 
![InBlock.gif][] \[Description( " 年龄 " )\] 
![InBlock.gif][] public int Age 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] get 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] return age; 
![ExpandedSubBlockEnd.gif][] \} 
![InBlock.gif][] set 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] age = value; 
![ExpandedSubBlockEnd.gif][] \} 
![ExpandedSubBlockEnd.gif][] \} 
![InBlock.gif][] 
![InBlock.gif][] \[Description( " 姓名 " )\] 
![InBlock.gif][] public String Name 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] get 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] return name; 
![ExpandedSubBlockEnd.gif][] \} 
![InBlock.gif][] set 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] name = value; 
![ExpandedSubBlockEnd.gif][] \} 
![ExpandedSubBlockEnd.gif][] \} 
![InBlock.gif][] 
![InBlock.gif][] \[Description( " 职业 " )\] 
![InBlock.gif][] public Metier CustomMetier 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] get 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] return metier; 
![ExpandedSubBlockEnd.gif][] \} 
![InBlock.gif][] set 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] metier = value; 
![ExpandedSubBlockEnd.gif][] \} 
![ExpandedSubBlockEnd.gif][] \} 
![InBlock.gif][] \[Description( " 地址集合 " )\] 
![InBlock.gif][] public Address CustomAddress 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] get 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] return address; 
![ExpandedSubBlockEnd.gif][] \} 
![ExpandedSubBlockEnd.gif][] \} 
![InBlock.gif][] 
![ExpandedSubBlockEnd.gif][] \#endregion 
![InBlock.gif][] 
![InBlock.gif][] protected override void Render(HtmlTextWriter output) 
![ExpandedSubBlockStart.gif][] \{ 
![InBlock.gif][] output.Write( " 姓名: " \+ Name \+ " " ); 
![InBlock.gif][] output.Write( " 年龄: " \+ Age \+ " " ); 
![InBlock.gif][] output.Write( " 职业: " \+ CustomMetier \+ " " ); 
![InBlock.gif][] output.Write( " 具体地址: " \+ CustomAddress.Street \+ " 城市: " 
![InBlock.gif][] \+ CustomAddress.City \+ " 国籍: " \+ 
![InBlock.gif][] CustomAddress.State \+ " 邮编: " \+ CustomAddress.Zip \+ " " ); 
![ExpandedSubBlockEnd.gif][] \} 
![ExpandedSubBlockEnd.gif][] \} 
![ExpandedBlockEnd.gif][]\} 
![None.gif][]

1.4 在asp.net页面定义控件,  
  
发现问题: 属性不是有效属性,如下图  
  
![ch1.jpg][]  
  
打开后台代码,输入如下代码检查属性,发现属性是存在的,如下图,再打开视图,发现控件能显示属性,唯一的就是不能认识属性为有效属性,在源视图也无法找到这几个属性.  
  
![ch2.jpg][]  
  
1.5 解决1.4无法显示有效属性的问题,(其实以上的测试已经实现复杂属性了).  
  
  解决方法: 请在Custom类中的CustomAddress中加入一个元数据(元数据的解释请参考MSDN),如下

![None.gif][]  \[Description( " 地址集合 " )\]  
![None.gif][] \[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)\]  
![None.gif][] public  Address CustomAddress  
![ExpandedBlockStart.gif][] \{  
![InBlock.gif][] get   
![ExpandedSubBlockStart.gif][] \{  
![InBlock.gif][] return  address;  
![ExpandedSubBlockEnd.gif][] \}   
![ExpandedBlockEnd.gif][] \}

再次打开源视图,发现编辑器已经支持此属性了,如下图,这样有点意思吧,呵呵  
  
![ch3.jpg][]  
  
虽然源视图上已经支持这个复杂属性了,打开属性面板,发现属性面板并不支持这个复杂属性(因为我们比较懒,不喜欢在源视图里编辑属性,想直接在属性面板编辑属性,下面就称复杂属性是CustomAddress),我们想要达到的效果,是让CustomAddress属性跟Font属性一样( 可以折叠 )显示在面板上,如下图  
  
![ch4.jpg][]  
  
发现问题: 属性面板并不支持这个复杂属性  
  
1.6 实现CustomAddress属性折叠效果  
  
解决方法: 给Address类添加一个元数据,如下

**![None.gif][]** \[TypeConverter( typeof (ExpandableObjectConverter))\]  
![None.gif][] public  class  Address  
![ExpandedBlockStart.gif][] \{ ![dot.gif][]. \}

编译后,再次打开属性面板,发现 CustomAddress属性已经支持折叠效果,如下图  
  
![ch5.jpg][]  
  
试着在属性面板编辑 CustomAddress的子属性, 修改好子属性以后然后运行页面,发现子属性修改数据后无效  
  
发现问题: 在属性面板编辑复杂属性的子属性无效  
  
1.7 解决属性面板编辑复杂属性的子属性无效的问题  
  
解决方法: 为Address类的每个属性加上一个元数据,如下

![None.gif][]  \[NotifyParentProperty(true)\]  
![None.gif][] public String Street  
![ExpandedBlockStart.gif][] ![dot.gif][] \{  
![InBlock.gif][]get  
![ExpandedSubBlockStart.gif][] \{  
![InBlock.gif][]return street;  
![ExpandedSubBlockEnd.gif][] \}   
![InBlock.gif][] set   
![ExpandedSubBlockStart.gif][] \{  
![InBlock.gif][] street = value;  
![ExpandedSubBlockEnd.gif][] \}   
![ExpandedBlockEnd.gif][] \}

编译后,回到原asp.net的页面,再次在属性面板里修改子属性,再次运行页面.发现修改后的数据生效了.  
  
好了,以上代码就是连字符形式的复杂属性的实现,我们接着继续,我们希望把 CustomAddress属性做为内镶属性使用,即如下代码的形式

**![None.gif][]** < custom:custom id = " Custom1 " runat = " server " name = " Clingingboy " CustomMetier = " 教师 " Age = " 21 " > 
![None.gif][] < CustomAddress City = " 杭州 " Street = " 不告诉你 " State = " 中国 " Zip = " 310000 " /> 
![None.gif][] </ custom:custom >

发现问题: 无法使用内镶属性  
  
1.8 实现内镶属性  
  
解决方法: 在Custom类中给CustomAddress再加入一个元数据(第三个),如下

![None.gif][]  \[Description( " 地址集合")\]  
![None.gif][] \[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)\]  
![None.gif][] \[PersistenceMode(PersistenceMode.InnerProperty)\]  
![None.gif][] public Address CustomAddress  
![ExpandedBlockStart.gif][] ![dot.gif][] \{  
![InBlock.gif][]get  
![ExpandedSubBlockStart.gif][] \{  
![InBlock.gif][]return address;  
![ExpandedSubBlockEnd.gif][] \}   
![ExpandedBlockEnd.gif][] \}

打开源视图( 请不要把原来的连字符属性去掉 ),在控件内部加入如下代码(编辑器已经支持此属性了)

![None.gif][] < custom:custom 
![None.gif][] CustomAddress \- Zip = " 3100001 " CustomAddress \- City = " 杭州1 " 
![None.gif][] CustomAddress \- State = " 中国1 " CustomAddress \- Street = " 不告诉你1 " 
![None.gif][] id = " Custom1 " runat = " server " name = " Clingingboy " CustomMetier = " 教师 " Age = " 21 " > 
![None.gif][] < CustomAddress City = " 杭州 " Street = " 不告诉你 " State = " 中国 " Zip = " 310000 " /> 
![None.gif][] </ custom:custom >

发现问题: 查看属性面板,再次修改CustomAddress子属性,然后运行,发现修改后无效果,而且显示的数据仍然是连字符属性的数据(非内镶属性的)  
  
1.9 让控件支持内镶属性  
  
解决方法: 给Custom类添加元数据,如下代码

![None.gif][]  \[ParseChildren( true )\]  
![None.gif][] public  class  Custom: Control  
![ExpandedBlockStart.gif][] \{ ![dot.gif][] \}

编译后,再次测试发现属性显示的 优先级 发生了变化,在内镶属性存在的时候,显示内镶属性,若其中有子属性不存在,则显示连字符属性,大家可以适当更改内镶属性和连字符属性测试变化.  
  
发现问题: 在属性面板改变属性时,仍然无法使修改后的数据生效,且修改后,数据退回初始的数据,并且导致内镶属性消失  
  
1.10 解决属性面板的问题  
  
解决方法: 给Custom类再添加一个元数据,如下代码

![None.gif][]  \[ParseChildren( true )\]  
![None.gif][] \[PersistChildren( false )\]  
![None.gif][] public  class  Custom: Control  
![ExpandedBlockStart.gif][] \{ ![dot.gif][] \}

编译后再次修改属性面板的值,发现修改的是内镶属性的数据,而且这次修改后数据没有丢失,运行后也是修改后的效果.  
  
好了,简单的讲完了.  
  
总结下:上面刚开始到1.3为止,其实效果已经实现了,接下来都是添加元数据,添加以后给我们带来的是方便.以上解决问题的办法全是套用元数据.可能上面的元数据大家很熟悉,在MSDN里面字面解释的也很清楚,但你去试验过吗?我相信这样的试验可以让你明白的更加深刻.  
  
这次讲的虽然很简单(难得我把这么简单的东西变的这么复杂),主要是学习学习方法了  
但我还是希望对大家有帮助,上面如果哪里讲错了还请指出来^\_^.  
  
[示例代码下载][Link 1] (请大家多修改):  
  
  
参考文章:  
  
[ASP.NET 2.0服务器控件开发之简单属性][ASP.NET 2.0]  
  
[ASP.NET 2.0服务器控件开发之复杂属性][ASP.NET 2.0 1]

[None.gif]: /images/20220527/c9fd66fa8ec54853b8e8ac84a4b1d050.png
[ExpandedBlockStart.gif]: /images/20220527/bcf4f14fd33949e8ae3d15662d11e8df.png
[ExpandedSubBlockStart.gif]: /images/20220527/86b35d43539b4e24a64e27cd2c486ea9.png
[InBlock.gif]: /images/20220527/5e753a9a93444e4ab839ca80a9ff361c.png
[ExpandedSubBlockEnd.gif]: /images/20220527/c5131a99842a434f9fd03e0eb6a04e04.png
[ExpandedBlockEnd.gif]: /images/20220527/e47d62b15a9041cda39398f5ff20a227.png
[ch1.jpg]: /images/20220527/6b00a695f3a64ff385fa87469c401285.png
[ch2.jpg]: /images/20220527/1ffa02b249d341abbeedc239da4dcbf7.png
[ch3.jpg]: /images/20220527/2e67b83cec844075b82d46cf29bcbf65.png
[ch4.jpg]: /images/20220527/8f1c041cc6214bfa9850d6db1775585a.png
[dot.gif]: /images/20220527/237cd9674ffe452989289a3d0747e007.png
[ch5.jpg]: /images/20220527/90597d746a2948fbb10d9b556a826c7f.png
[Link 1]: http://files.cnblogs.com/Clingingboy/ServerControl/Code5.rar
[ASP.NET 2.0]: http://dev.yesky.com/msdn/118/2439618.shtml
[ASP.NET 2.0 1]: http://dev.yesky.com/msdn/383/2438883.shtml