HtmlTextArea.OnServerChange(EventArgs) Metode
Definisi
Penting
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Menaikkan ServerChange peristiwa HtmlTextArea kontrol. Ini memungkinkan Anda untuk menyediakan handler kustom untuk peristiwa tersebut.
protected:
virtual void OnServerChange(EventArgs ^ e);protected virtual void OnServerChange (EventArgs e);abstract member OnServerChange : EventArgs -> unit
override this.OnServerChange : EventArgs -> unitProtected Overridable Sub OnServerChange (e As EventArgs)Parameter
Contoh
Contoh kode berikut menunjukkan cara menentukan dan membuat penanganan aktivitas kustom untuk peristiwa tersebut ServerChange . Pesan ditampilkan saat nilai yang dimasukkan dalam HtmlTextArea kontrol melebihi 20 karakter.
<%@ Page Language="C#" AutoEventWireup="True" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
void Server_Change(Object sender, EventArgs e)
{
// The ServerChange event is commonly used for data validation.
// This method determines whether the comment entered into the
// HtmlTextArea control is longer than 20 characters.
if (TextArea1.Value.Length > 20)
Span1.InnerHtml = "Your comment cannot exceed 20 characters.";
else
Span1.InnerHtml = "You wrote: <br />" + TextArea1.Value;
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>HtmlTextArea ServerChange Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>HtmlTextArea ServerChange Example</h3>
Enter your comments: <br />
<textarea rows="2" cols="20" id="TextArea1"
onserverchange="Server_Change"
runat="server"/>
<br />
<input type="submit"
value="Submit"
runat="server"/>
<br />
<span id="Span1"
runat="server" />
</form>
</body>
</html>
<%@ Page Language="VB" AutoEventWireup="True" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Sub Server_Change(ByVal sender As Object, ByVal e As EventArgs)
' The ServerChange event is commonly used for data validation.
' This method determines whether the comment entered into the
' HtmlTextArea control is longer than 20 characters.
If TextArea1.Value.Length > 20 Then
Span1.InnerHtml = "Your comment cannot exceed 20 characters."
Else
Span1.InnerHtml = "You wrote: <br />" + TextArea1.Value
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>HtmlTextArea ServerChange Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>HtmlTextArea ServerChange Example</h3>
Enter your comments: <br />
<textarea rows="2" cols="20" id="TextArea1"
onserverchange="Server_Change"
runat="server"/>
<br />
<input type="submit"
value="Submit"
runat="server"/>
<br />
<span id="Span1"
runat="server" />
</form>
</body>
</html>
<%@ Page Language="C#" AutoEventWireup="True" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
void Server_Change(Object sender, EventArgs e)
{
// The ServerChange event is commonly used for data validation.
// This method determines whether the comment entered into the
// HtmlTextArea control is longer than 20 characters.
if (TextArea1.Value.Length > 20)
{
Span1.InnerHtml = "Your comment cannot exceed 20 characters.";
}
else
{
Span1.InnerHtml = "You wrote: <br />" + TextArea1.Value;
}
}
void Page_Load(Object sender, EventArgs e)
{
// Create an EventHandler delegate for the method you want to
// handle the event, and then add it to the list of methods
// called when the event is raised.
TextArea1.ServerChange +=
new System.EventHandler(this.Server_Change);
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>HtmlTextArea ServerChange Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>HtmlTextArea ServerChange Example</h3>
Enter your comments (20 or fewer characters): <br />
<textarea rows="2" cols="20" id="TextArea1"
runat="server"/>
<br />
<input type="submit"
value="Submit"
runat="server"/>
<br />
<span id="Span1"
runat="server" />
</form>
</body>
</html>
<%@ Page Language="VB" AutoEventWireup="True" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Sub Server_Change(ByVal sender As Object, ByVal e As EventArgs)
' The ServerChange event is commonly used for data validation.
' This method determines whether the comment entered into the
' HtmlTextArea control is longer than 20 characters.
If TextArea1.Value.Length > 20 Then
Span1.InnerHtml = "Your comment cannot exceed 20 characters."
Else
Span1.InnerHtml = "You wrote: <br />" + TextArea1.Value
End If
End Sub
Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
' Create an EventHandler delegate for the method you want to
' handle the event, and then add it to the list of methods
' called when the event is raised.
AddHandler TextArea1.ServerChange, AddressOf Server_Change
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>HtmlTextArea ServerChange Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>HtmlTextArea ServerChange Example</h3>
Enter your comments (20 or fewer characters): <br />
<textarea rows="2" cols="20" id="TextArea1"
runat="server"/>
<br />
<input type="submit"
value="Submit"
runat="server"/>
<br />
<span id="Span1"
runat="server" />
</form>
</body>
</html>
Keterangan
Peristiwa ServerChange dimunculkan ketika konten HtmlTextArea kontrol berubah antara postingan ke server.
Catatan
Kejadian ini hanya dimunculkan ketika pengguna memulai postingan ke server, seperti dengan mengklik submit tombol. Kejadian ini tidak menyebabkan terjadinya postingan ke server.
Catatan
Kontrol harus mengaktifkan viewstate agar ServerChange kejadian berfungsi dengan benar.
Kejadian ini biasanya digunakan untuk melakukan validasi data pada HtmlTextArea kontrol saat pengguna memperbarui teks dalam kontrol.
Menaikkan peristiwa memanggil penanganan aktivitas melalui delegasi. Untuk informasi selengkapnya, lihat Menangani dan Meningkatkan Peristiwa.
Metode ini OnServerChange juga memungkinkan kelas turunan untuk menangani peristiwa tanpa melampirkan delegasi. Ini adalah teknik yang disukai untuk menangani peristiwa di kelas turunan.
Catatan Bagi Inheritor
Saat mengambil alih di kelas turunan OnServerChange(EventArgs) , pastikan untuk memanggil metode kelas OnServerChange(EventArgs) dasar sehingga delegasi terdaftar menerima peristiwa tersebut.
