ASP.NET Tutorial/Page Lifecycle/Page Events
Содержание
Error event example
<source lang="csharp">
<%@ Page Language="vb" %> <html>
<head>
<title>Error event example</title>
<script runat="server">
Sub Page_Load()
Dim x, y, overflow As Integer
x = 1
y = 0
overflow = x / y
End Sub
Sub Page_Error()
Response.Write(Server.GetLastError.ToString())
Server.ClearError
End Sub
</script>
</head>
<body>
<asp:label id="Message" runat="server"/>
</body> </html></source>
Here is the sequence of events that are raised whenever you request a page:
<source lang="csharp">
1. PreInit
2. Init 3. InitComplete 4. PreLoad 5. Load 6. LoadComplete 7. PreRender 8. PreRenderComplete 9. SaveStateComplete 10. Unload
<%@ Page Language="C#" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server">
void Page_Load(object sender, EventArgs e)
{
Label1.Text = "Page Load";
}
void Button1_Click(object sender, EventArgs e)
{
Label1.Text += "
Button Click";
}
void Page_PreRender()
{
Label1.Text += "
Page PreRender";
}
</script> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">
<title>Show Page Events</title>
</head> <body>
<form id="form1" runat="server">
<asp:Button
id="Button1"
Text="Click Here"
OnClick="Button1_Click"
Runat="server" />
<asp:Label
id="Label1"
Runat="server" />
</form>
</body> </html></source>
Page events firing sequence (VB.net)
<source lang="csharp">
<%@ Page Language="VB" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server">
Sub Page_Load()
Label1.Text = "Page Load"
End Sub
Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs)
Label1.Text &= "
Button Click"
End Sub
Sub Page_PreRender()
Label1.Text &= "
Page PreRender"
End Sub
</script> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">
<title>Show Page Events</title>
</head> <body>
<form id="form1" runat="server">
<asp:Button
id="Button1"
Text="Click Here"
OnClick="Button1_Click"
Runat="server" />
<asp:Label
id="Label1"
Runat="server" />
</form>
</body> </html></source>
Page flow tracing
<source lang="csharp">
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="PageFlowTracing" Trace="true"%> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">
<title>Page Flow</title>
</head> <body>
<form id="form1" runat="server">
<asp:Label id="lblInfo"
runat="server" EnableViewState="False"/>
<asp:Button id="Button1"
runat="server"
Text="Button" OnClick="Button1_Click"/>
</form>
</body> </html> File: Default.aspx.cs
using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class PageFlowTracing : System.Web.UI.Page {
private void Page_Load(object sender, System.EventArgs e)
{
lblInfo.Text += "Page.Load event handled.
";
if (Page.IsPostBack)
{
lblInfo.Text += "This is the second time you"ve seen this page.
";
}
}
private void Page_Init(object sender, System.EventArgs e)
{
lblInfo.Text += "Page.Init event handled.
";
}
protected void Button1_Click(object sender, System.EventArgs e)
{
Trace.Write("Button1_Click", "About to update the label.");
lblInfo.Text += "Button1.Click event handled.";
Trace.Write("Button1_Click", "Label updated.");
}
private void Page_PreRender(object sender, System.EventArgs e)
{
lblInfo.Text += "Page.PreRender event handled.
";
}
private void Page_Unload(object sender, System.EventArgs e)
{
lblInfo.Text += "Page.Unload event handled.
";
}
}</source>
Page life cycle events
<source lang="csharp">
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="PageFlow" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">
<title>Page Flow</title>
</head> <body>
<form id="form1" runat="server">
<asp:Label id="lblInfo" runat="server" EnableViewState="False">
</asp:Label>
<asp:Button id="Button1" runat="server"
Text="Button" OnClick="Button1_Click"></asp:Button>
</form>
</body> </html> File: Default.aspx.cs using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class PageFlow : System.Web.UI.Page {
private void Page_Load(object sender, System.EventArgs e)
{
lblInfo.Text += "Page.Load event handled.
";
if (Page.IsPostBack)
{
lblInfo.Text += "second time
";
}
}
private void Page_Init(object sender, System.EventArgs e)
{
lblInfo.Text += "Page.Init event handled.
";
}
protected void Button1_Click(object sender, System.EventArgs e)
{
lblInfo.Text += "Button1.Click event handled.
";
}
private void Page_PreRender(object sender, System.EventArgs e)
{
lblInfo.Text += "Page.PreRender event handled.
";
}
private void Page_Unload(object sender, System.EventArgs e)
{
lblInfo.Text += "Page.Unload event handled.
";
}
}</source>
Unload event example
<source lang="csharp">
<%@ Page Language="vb" %> <html>
<head>
<title>Unload event example</title>
<script runat="server">
Dim TheFile As System.IO.StreamReader
Sub Page_Load()
TheFile = System.IO.File.OpenText(MapPath("Init.aspx"))
Message.Text = "" & Server.HtmlEncode(TheFile.ReadToEnd()) & ""
End Sub
Sub Page_Unload()
TheFile.Close()
End Sub
</script>
</head>
<body>
<asp:label id="Message" runat="server"/>
</body> </html></source>
