ASP.NET AJAX入门系列(5):使用UpdatePanel控件(二)

UpdatePanel可以用来创建丰富的局部更新Web应用程序,它是ASP.NET 2.0 AJAX Extensions中很重要的一个控件,其强大之处在于不用编写任何客户端脚本,只要在一个页面上添加几个UpdatePanel控件和一个ScriptManager控件就可以自动实现局部更新。通过本文来学习一下UpdatePanel其他的一些使用方法(第二篇)。

 

主要内容

1.用编程的方法控制UpdatePanel的更新

2UpdatePanel的嵌套使用

3.同一页面上使用多个UpdatePanel

 

一.用编程的方法控制UpdatePanel的更新

对于UpdatePanel,我们也可以使用编程的方法来控制它的更新,可以通过ScriptManagerRegisterAsyncPostBackControl()方法注册一个异步提交的控件,并且调用UpdatePanelUpdate()方法来让它更新。再次用我在前面的文章中用到的一个无聊的时间更新例子来看一下,有时候我觉得例子过于复杂更加不好说明白所要讲的内容,如下代码所示,注意Button1并不包含在UpdatePanel中:

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<script runat="server">

    
void Button1_Click(object sender, EventArgs e)

    
{

        
this.Label2.Text = DateTime.Now.ToString();

    }


</script>

<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

    
<title>Refreshing an UpdatePanel Programmatically</title>

</head>

<body>

    
<form id="form1" runat="server">

        
<asp:ScriptManager ID="ScriptManager1" runat="server"/>

        
<div>

            
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">

                
<ContentTemplate>

                    
<asp:Label ID="Label1" runat="server" Text="更新时间:"></asp:Label>

                    
<asp:Label ID="Label2" runat="server" Text="Label" ForeColor="Red"></asp:Label><br/><br/>

                    

                
</ContentTemplate>

            
</asp:UpdatePanel>

             
<asp:Button ID="Button1" runat="server" Text="Button"  OnClick = "Button1_Click"/>

        
</div>

    
</form>

</body>

</html>

这时候不用多说,肯定是整页提交了,运行如下图所示:

再次修改上面的例子,使用ScriptManagerRegisterAsyncPostBackControl()注册Button1为一个异步提交控件,并且调用UpdatePanelUpdate()方法:

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<script runat="server">

    
void Page_Load(object sender, EventArgs e)

    
{

        ScriptManager1.RegisterAsyncPostBackControl(Button1);

    }


    

    
void Button1_Click(object sender, EventArgs e)

    
{

        
this.Label2.Text = DateTime.Now.ToString();

        
this.UpdatePanel1.Update();

    }


</script>

<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

    
<title>Refreshing an UpdatePanel Programmatically</title>

</head>

<body>

    
<form id="form1" runat="server">

        
<asp:ScriptManager ID="ScriptManager1" runat="server"/>

        
<div>

            
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">

                
<ContentTemplate>

                    
<asp:Label ID="Label1" runat="server" Text="更新时间:"></asp:Label>

                    
<asp:Label ID="Label2" runat="server" Text="Label" ForeColor="Red"></asp:Label><br/><br/>

                    

                
</ContentTemplate>

            
</asp:UpdatePanel>

             
<asp:Button ID="Button1" runat="server" Text="Button"  OnClick = "Button1_Click"/>

        
</div>

    
</form>

</body>

</html>

这时候可以看到,已经是异步提交了:

二. UpdatePanel的嵌套使用

UpdatePanel还可以嵌套使用,即在一个UpdatePanelContentTemplate中还可以放入另一个UpdatePanel。当最外面的UpdatePanel被触发更新时,它里面的子UpdatePanel也随着更新,里面的UpdatePanel触发更新时,只更新它自己,而不会更新外层的UpdatePanel。看下面的例子:

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %>

<script runat="server">

</script>

 

<html xmlns="http://www.w3.org/1999/xhtml">

<head id="Head1" runat="server">

    
<title>UpdatePanelUpdateMode Example</title>

    
<style type="text/css">

    div.NestedPanel

    
{

      position
: relative;

      margin
: 2% 5% 2% 5%;

    
}


    
</style>

</head>

<body>

    
<form id="form1" runat="server">

        
<div>

            
<asp:ScriptManager ID="ScriptManager" 

                               runat
="server" />

            
<asp:UpdatePanel ID="OuterPanel" 

                             UpdateMode
="Conditional" 

                             runat
="server">

                
<ContentTemplate>

                    
<div>

                        
<fieldset>

                            
<legend>Outer Panel </legend>

                            
<br />

                            
<asp:Button ID="OPButton1" 

                                        Text
="Outer Panel Button" 

                                        runat
="server" />

                            
<br />

                            Last updated on

                            
<%= DateTime.Now.ToString() %>

                            
<br />

                            
<br />

                            
<asp:UpdatePanel ID="NestedPanel1" 

                                               UpdateMode
="Conditional"

                                               runat
="server">

                                
<ContentTemplate>

                                    
<div class="NestedPanel">

                                        
<fieldset>

                                            
<legend>Nested Panel 1</legend>

                                            
<br />

                                            Last updated on

                                            
<%= DateTime.Now.ToString() %>

                                            
<br />

                                            
<asp:Button ID="NPButton1"

                                                        Text
="Nested Panel 1 Button" 

                                                        runat
="server" />

                                        
</fieldset>

                                    
</div>

                                
</ContentTemplate>

                            
</asp:UpdatePanel>

                        
</fieldset>

                    
</div>

                
</ContentTemplate>

            
</asp:UpdatePanel>

        
</div>

    
</form>

</body>

</html>

运行后如下:

三.同一页面上使用多个UpdatePanel

使用UpdatePanel的时候并没有限制在一个页面上用多少个UpdatePanel,所以我们可以为不同的需要局部更新的页面区域加上不同的UpdatePanel。由于UpdatePanel默认的UpdateModeAlways,如果页面上有一个局部更新被触发,则所有的UpdatePanel都将更新,这是我们不愿看到的,我们只需要UpdatePanel在它自己的触发器触发的时候更新就可以了,所以需要把UpdateMode设置为Conditional

来看一下官方网站上提供的一个例子:包括两个UpdatePanel,其中一个用来用户输入而另一个则用来显示数据,每一个UpdatePanelUpdateMode属性都设置为Conditional。当我们单击Cancel按钮时,只有用来用户输入的那个UpdatePanel刷新,当单击Insert按钮时,两个UpdatePanel都刷新。代码如下:

<%@ Page Language="C#" %>

<%@ Import Namespace="System.Collections.Generic" %>

 

<html xmlns="http://www.w3.org/1999/xhtml" >

<head id="Head1" runat="server">

    
<title>Enter New Employees</title>

    
<script runat="server">

        private List
<Employee> EmployeeList;

 

        protected 
void Page_Load()

        
{

            
if (!IsPostBack)

            
{

                EmployeeList 
= new List<Employee>();

                EmployeeList.Add(
new Employee(1"Jump""Dan"));

                EmployeeList.Add(
new Employee(2"Kirwan""Yvette"));

                ViewState[
"EmployeeList"= EmployeeList;

            }


            
else

                EmployeeList 
= (List<Employee>)ViewState["EmployeeList"];

            

            EmployeesGridView.DataSource 
= EmployeeList;

            EmployeesGridView.DataBind();

        }


        

        protected 
void InsertButton_Click(object sender, EventArgs e)

        
{

            
if (String.IsNullOrEmpty(FirstNameTextBox.Text) ||

               String.IsNullOrEmpty(LastNameTextBox.Text)) 
return; }

 

            
int employeeID = EmployeeList[EmployeeList.Count-1].EmployeeID + 1;

            

            string lastName 
= Server.HtmlEncode(FirstNameTextBox.Text);

            string firstName 
= Server.HtmlEncode(LastNameTextBox.Text);

            

            FirstNameTextBox.Text 
= String.Empty;

            LastNameTextBox.Text 
= String.Empty;

            

            EmployeeList.Add(
new Employee(employeeID, lastName, firstName));

            ViewState[
"EmployeeList"= EmployeeList;

            

            EmployeesGridView.DataBind();

            EmployeesGridView.PageIndex 
= EmployeesGridView.PageCount;

        }


 

        protected 
void CancelButton_Click(object sender, EventArgs e)

        
{

            FirstNameTextBox.Text 
= String.Empty;

            LastNameTextBox.Text 
= String.Empty;

        }


    

        [Serializable]

        public class Employee

        
{

            private 
int _employeeID;

            private string _lastName;

            private string _firstName;

 

            public 
int EmployeeID

            
{

                get 
return _employeeID; }

            }


            

            public string LastName

            
{

                get 
return _lastName; }

            }


            

            public string FirstName

            
{

                get 
return _firstName; }

            }


            

            public Employee(
int employeeID, string lastName, string firstName)

            
{

                _employeeID 
= employeeID;

                _lastName 
= lastName;

                _firstName 
= firstName;

            }


        }


 

    
</script>

</head>

<body>

    
<form id="form1" runat="server">

    
<div>

        
&nbsp;</div>

        
<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePartialRendering="true" />

        
<table>

            
<tr>

                
<td style="height: 206px" valign="top">

                    
<asp:UpdatePanel ID="InsertEmployeeUpdatePanel" runat="server" UpdateMode="Conditional">

                        
<ContentTemplate>

                          
<table cellpadding="2" border="0" style="background-color:#7C6F57">

                            
<tr>

                              
<td><asp:Label ID="FirstNameLabel" runat="server" AssociatedControlID="FirstNameTextBox" 

                                             Text
="First Name" ForeColor="White" /></td>

                              
<td><asp:TextBox runat="server" ID="FirstNameTextBox" /></td>

                            
</tr>

                            
<tr>

                              
<td><asp:Label ID="LastNameLabel" runat="server" AssociatedControlID="LastNameTextBox" 

                                             Text
="Last Name" ForeColor="White" /></td>

                              
<td><asp:TextBox runat="server" ID="LastNameTextBox" /></td>

                            
</tr>

                            
<tr>

                              
<td></td>

                              
<td>

                                
<asp:LinkButton ID="InsertButton" runat="server" Text="Insert" OnClick="InsertButton_Click" ForeColor="White" />

                                
<asp:LinkButton ID="Cancelbutton" runat="server" Text="Cancel" OnClick="CancelButton_Click" ForeColor="White" />

                              
</td>

                            
</tr>

                          
</table>

                          
<asp:Label runat="server" ID="InputTimeLabel"><%=DateTime.Now %></asp:Label>

                        
</ContentTemplate>

                    
</asp:UpdatePanel>

                
</td>

                
<td style="height: 206px" valign="top">

                    
<asp:UpdatePanel ID="EmployeesUpdatePanel" runat="server" UpdateMode="Conditional">

                        
<ContentTemplate>

                            
<asp:GridView ID="EmployeesGridView" runat="server" BackColor="LightGoldenrodYellow" BorderColor="Tan"

                                BorderWidth
="1px" CellPadding="2" ForeColor="Black" GridLines="None" AutoGenerateColumns="False">

                                
<FooterStyle BackColor="Tan" />

                                
<SelectedRowStyle BackColor="DarkSlateBlue" ForeColor="GhostWhite" />

                                
<PagerStyle BackColor="PaleGoldenrod" ForeColor="DarkSlateBlue" HorizontalAlign="Center" />

                                
<HeaderStyle BackColor="Tan" Font-Bold="True" />

                                
<AlternatingRowStyle BackColor="PaleGoldenrod" />

                                
<Columns>

                                    
<asp:BoundField DataField="EmployeeID" HeaderText="Employee ID" />

                                    
<asp:BoundField DataField="LastName" HeaderText="Last Name" />

                                    
<asp:BoundField DataField="FirstName" HeaderText="First Name" />

                                
</Columns>

                                
<PagerSettings PageButtonCount="5" />

                            
</asp:GridView>

                            
<asp:Label runat="server" ID="ListTimeLabel"><%=DateTime.Now %></asp:Label>

                        
</ContentTemplate>

                        
<Triggers>

                            
<asp:AsyncPostBackTrigger ControlID="InsertButton" EventName="Click" />

                        
</Triggers>

                    
</asp:UpdatePanel>

                
</td>

            
</tr>

        
</table>

    
</form>

</body>

</html>

运行后效果如下:

 

示例代码下载:https://files.cnblogs.com/Terrylee/ASPNETAJAXUpdatePanelDemo2.rar

posted @ 2006-11-01 22:00  TerryLee  阅读(40561)  评论(69编辑  收藏  举报