ASP.NET 动态添加自定义控件
2009-09-24 08:37 于为源 阅读(4215) 评论(0) 收藏 举报
动态添加自定义控件能加载控件不同设计的风格。满足不同的需求下面的动态添加就是实现，当用户选择不同的问题类型时那么问题的控件也就不同，取决于用户所选的问题类型，这里只设计两个问题的自定义控件，实现控件的动态加载，两个控件的代码如下：（我的两个控件都是将源于后台写在同一个页面）
ASPNetSurvey.ascx：
ASPSurvey.ascx： <%@ Control Language="C#" ClassName="ASPSurvey" %>
WebSurvey.aspx：
第一：对于加载的动态控件，如果包含自定义的属性和方法，那么在引用的时候必须使用<%@Reference%>,这里就有个区别了，如果是直接加载一个没有添加自定义成分的用户控件，则之需要用Page.Load()方法即可，一旦有自定义的成分（属性，方法，事件。。）就需要引用上面的指令了。如果不是动态添加的话，我们一般是使用<%@ Register %>指令<%@Reference%>，这两个怎么区分理解呢：前一个指令 是“引用”，毕竟这个控件没用放到这个页面临时加载而已，故只需要引用就够了，对于不是动态的我们用后一个指令“注册”，这样的指令可以理解为：我需要把一个控件拖到我的页面，贮存在我的页面，需要长时间存在了（除非你删除），那么我就需要注册了，这其实跟生活中的例子一样
第二，用户控件都是控件类，都是在System.Web.UI下的控件类，这里在引用ascx文件的控件类的属性时，只需要先实例化引用的用户控件类，在获取类中的属性。运行效果如下：
ASPNetSurvey.ascx：
1
<%@ Control Language="C#" ClassName="ASPNetSurvey" %>
2
3<script runat="server">
4
5 public bool KnowFast
6
{
7
get
8
{
9 return chkFast.Checked;
10
}
11
}
12
13 public bool KnowNewest
14 {
15 get
16 {
17 return chkNewest.Checked;
18 }
19 }
20
21</script>
22
23<asp:CheckBox ID="chkFast" Text="Did you know that ASP.NET is fast?" runat="server" />
24<br />
25<br />
26<asp:CheckBox ID="chkNewest" Text="Did you know that ASP.NET is the newest Microsoft
27 technology for building Web applications?" runat="server" />
28<br />
29<br />
30
31
32
上面这个界面有两个属性，获取页面中Checkbox的选定状态，下面一个同样： <%@ Control Language="C#" ClassName="ASPNetSurvey" %>2
3
<script runat="server">4
5
public bool KnowFast6
{
7
get8
{
9
return chkFast.Checked;10
}11
}12
13
public bool KnowNewest14
{15
get16
{17
return chkNewest.Checked;18
}19
} 20
21
</script>22
23
<asp:CheckBox ID="chkFast" Text="Did you know that ASP.NET is fast?" runat="server" />24
<br />25
<br />26
<asp:CheckBox ID="chkNewest" Text="Did you know that ASP.NET is the newest Microsoft27
technology for building Web applications?" runat="server" />28
<br />29
<br />30
31
32
ASPSurvey.ascx： <%@ Control Language="C#" ClassName="ASPSurvey" %>
1<%@ Control Language="C#" ClassName="ASPSurvey" %>
2
3<script runat="server">
4
5 public bool KnowSlow
6 {
7 get
8 {
9 return chkSlow.Checked;
10 }
11 }
12
13 public bool KnowOutdated
14 {
15 get
16 {
17 return chkOutdated.Checked;
18 }
19 }
20
21</script>
22
23<asp:CheckBox ID="chkSlow" Text="Did you know that ASP Classic is slow?" runat="server" />
24<br />
25<br />
26<asp:CheckBox ID="chkOutdated" Text="Did you know that ASP Classic is outdated?"
27 runat="server" />
28<br />
29<br />
30
31
下面这一个是动态调用这两个控件的代码（源与后台代码在同一个界面）： <%@ Control Language="C#" ClassName="ASPSurvey" %>2
3
<script runat="server">4
5
public bool KnowSlow6
{7
get8
{9
return chkSlow.Checked;10
}11
}12
13
public bool KnowOutdated14
{15
get16
{17
return chkOutdated.Checked;18
}19
} 20
21
</script>22
23
<asp:CheckBox ID="chkSlow" Text="Did you know that ASP Classic is slow?" runat="server" />24
<br />25
<br />26
<asp:CheckBox ID="chkOutdated" Text="Did you know that ASP Classic is outdated?"27
runat="server" />28
<br />29
<br />30
31
WebSurvey.aspx：
1<%@ Page Language="C#" %>
2
3<%@ Reference Control="~/ASPSurvey.ascx" %>
4<%@ Reference Control="~/ASPNetSurvey.ascx" %>
5<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
6
7<script runat="server">
8
9 private Control _survey = null;
10
11 void Page_Load()
12 {
13 switch(ddlLanguage.SelectedIndex)
14 {
15 case 1:
16 _survey = Page.LoadControl("ASPSurvey.ascx");
17 break;
18 case 2:
19 _survey = Page.LoadControl("ASPNetSurvey.ascx");
20 break;
21 }
22
23 if(_survey != null)
24 PlaceHolder1.Controls.Add(_survey);
25 }
26
27 protected void btnSubmit_Click(object sender ,EventArgs e)
28 {
29 switch(ddlLanguage.SelectedIndex)
30 {
31 case 1:
32 ASPSurvey aspResults = (ASPSurvey)_survey;
33 ltlResults.Text = "<h1>ASP Survey</h1>";
34 ltlResults.Text += "<br />Know slow? " + aspResults.KnowSlow.ToString();
35 ltlResults.Text += "<br />Know outdated? " + aspResults.KnowOutdated.ToString();
36 break;
37 case 2:
38 ASPNetSurvey aspNetResults = (ASPNetSurvey)_survey;
39 ltlResults.Text = "<h1>ASP.NET Survey</h1>";
40 ltlResults.Text += "<br />Know fast? " + aspNetResults.KnowFast.ToString();
41 ltlResults.Text += "<br />Know newest? " + aspNetResults.KnowNewest.ToString();
42 break;
43 }
44 }
45</script>
46
47<html xmlns="http://www.w3.org/1999/xhtml">
48<head id="Head1" runat="server">
49 <style type="text/css">
50 html
51 {
52 font:14px Arial,Sans-Serif;
53 }
54 </style>
55 <title>Web Survey</title>
56</head>
57<body>
58 <form id="form1" runat="server">
59 <div>
60 <asp:Label ID="lblLanguage" Text="What language do you use to develop Web applications?"
61 runat="server" />
62 <br />
63 <asp:DropDownList ID="ddlLanguage" ToolTip="Web application language (reloads form)"
64 AutoPostBack="true" runat="server">
65 <asp:ListItem Text="Select Language" />
66 <asp:ListItem Text="ASP Classic" />
67 <asp:ListItem Text="ASP.NET" />
68 </asp:DropDownList>
69 <br />
70 <br />
71 <asp:PlaceHolder ID="PlaceHolder1" runat="server" />
72 <asp:Button ID="btnSubmit" Text="Submit" OnClick="btnSubmit_Click" runat="server" />
73 <hr />
74 <asp:Literal ID="ltlResults" runat="server" />
75 </div>
76 </form>
77</body>
78</html>
79
80
81
上面这个页面的代码，有很多地方需要提出来一下：<%@ Page Language="C#" %>2
3
<%@ Reference Control="~/ASPSurvey.ascx" %>4
<%@ Reference Control="~/ASPNetSurvey.ascx" %>5
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">6
7
<script runat="server">8
9
private Control _survey = null;10
11
void Page_Load()12
{13
switch(ddlLanguage.SelectedIndex)14
{15
case 1:16
_survey = Page.LoadControl("ASPSurvey.ascx");17
break;18
case 2:19
_survey = Page.LoadControl("ASPNetSurvey.ascx");20
break;21
}22
23
if(_survey != null)24
PlaceHolder1.Controls.Add(_survey);25
}26
27
protected void btnSubmit_Click(object sender ,EventArgs e)28
{29
switch(ddlLanguage.SelectedIndex)30
{31
case 1:32
ASPSurvey aspResults = (ASPSurvey)_survey;33
ltlResults.Text = "<h1>ASP Survey</h1>";34
ltlResults.Text += "<br />Know slow? " + aspResults.KnowSlow.ToString();35
ltlResults.Text += "<br />Know outdated? " + aspResults.KnowOutdated.ToString();36
break;37
case 2:38
ASPNetSurvey aspNetResults = (ASPNetSurvey)_survey;39
ltlResults.Text = "<h1>ASP.NET Survey</h1>";40
ltlResults.Text += "<br />Know fast? " + aspNetResults.KnowFast.ToString();41
ltlResults.Text += "<br />Know newest? " + aspNetResults.KnowNewest.ToString();42
break;43
}44
}45
</script>46
47
<html xmlns="http://www.w3.org/1999/xhtml">48
<head id="Head1" runat="server">49
<style type="text/css">50
html51
{52
font:14px Arial,Sans-Serif;53
}54
</style>55
<title>Web Survey</title>56
</head>57
<body>58
<form id="form1" runat="server">59
<div>60
<asp:Label ID="lblLanguage" Text="What language do you use to develop Web applications?"61
runat="server" />62
<br />63
<asp:DropDownList ID="ddlLanguage" ToolTip="Web application language (reloads form)"64
AutoPostBack="true" runat="server">65
<asp:ListItem Text="Select Language" />66
<asp:ListItem Text="ASP Classic" />67
<asp:ListItem Text="ASP.NET" />68
</asp:DropDownList>69
<br />70
<br />71
<asp:PlaceHolder ID="PlaceHolder1" runat="server" />72
<asp:Button ID="btnSubmit" Text="Submit" OnClick="btnSubmit_Click" runat="server" />73
<hr />74
<asp:Literal ID="ltlResults" runat="server" />75
</div>76
</form>77
</body>78
</html>79
80
81
第一：对于加载的动态控件，如果包含自定义的属性和方法，那么在引用的时候必须使用<%@Reference%>,这里就有个区别了，如果是直接加载一个没有添加自定义成分的用户控件，则之需要用Page.Load()方法即可，一旦有自定义的成分（属性，方法，事件。。）就需要引用上面的指令了。如果不是动态添加的话，我们一般是使用<%@ Register %>指令<%@Reference%>，这两个怎么区分理解呢：前一个指令 是“引用”，毕竟这个控件没用放到这个页面临时加载而已，故只需要引用就够了，对于不是动态的我们用后一个指令“注册”，这样的指令可以理解为：我需要把一个控件拖到我的页面，贮存在我的页面，需要长时间存在了（除非你删除），那么我就需要注册了，这其实跟生活中的例子一样
第二，用户控件都是控件类，都是在System.Web.UI下的控件类，这里在引用ascx文件的控件类的属性时，只需要先实例化引用的用户控件类，在获取类中的属性。运行效果如下：
本文来自博客园，作者：于为源，转载请注明原文链接：https://www.cnblogs.com/yuanyuan/archive/2009/09/24/1573019.html
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