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>
复制代码 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>
复制代码 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: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>
- </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>
复制代码 运行后效果如下:
示例代码下载:http://files.cnblogs.com/Terrylee/ASPNETAJAXUpdatePanelDemo2.rar |