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

2.UpdatePanel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ScriptManager的RegisterAsyncPostBackControl()方法注册一个异步提交的控件,并且调用UpdatePanel的Update()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:

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

再次修改上面的例子,使用ScriptManager的RegisterAsyncPostBackControl()注册Button1为一个异步提交控件,并且调用UpdatePanel的Update()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:

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

二. UpdatePanel的嵌套使用

UpdatePanel还可以嵌套使用,即在一个UpdatePanel的ContentTemplate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:
ASP.NET AJAX入门系列(5):使用UpdatePanel控件(二)

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UpdateMode是Always,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UpdatePanel的UpdateMode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:

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

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

你可能感兴趣的:(asp.net)