CommandEventHandler Delegat

Definicja

Reprezentuje metodę, która będzie obsługiwać Command zdarzenie.Represents the method that will handle the Command event.

public delegate void CommandEventHandler(System::Object ^ sender, CommandEventArgs ^ e);
public delegate void CommandEventHandler(object sender, CommandEventArgs e);
type CommandEventHandler = delegate of obj * CommandEventArgs -> unit
Public Delegate Sub CommandEventHandler(sender As Object, e As CommandEventArgs)

Parametry

sender
Object

Źródło zdarzenia.The source of the event.

e
CommandEventArgs

A CommandEventArgs , który zawiera dane zdarzenia.A CommandEventArgs that contains the event data.

Dziedziczenie
CommandEventHandler

Przykłady

W poniższym przykładzie pokazano, jak określić i zakodować procedurę obsługi dla Command zdarzenia Button kontrolki.The following example demonstrates how to specify and code a handler for the Command event of a Button control. Ten przykład określa procedurę obsługi zdarzeń deklaratywnie przy użyciu OnClick właściwości Button kontrolki.This example specifies the event handler declaratively, using the OnClick property of the Button control.

<%@ 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">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Button CommandName Example</title>
<script runat="server">

      void CommandBtn_Click(Object sender, CommandEventArgs e) 
      {

         switch(e.CommandName)
         {

            case "Sort":

               // Call the method to sort the list.
               Sort_List((String)e.CommandArgument);
               break;

            case "Submit":

               // Display a message for the Submit button being clicked.
               Message.Text = "You clicked the Submit button";

               // Test whether the command argument is an empty string ("").
               if((String)e.CommandArgument == "")
               {
                  // End the message.
                  Message.Text += ".";
               }
               else
               {
                  // Display an error message for the command argument. 
                  Message.Text += ", however the command argument is not recogized.";
               }                
               break;

            default:

               // The command name is not recognized. Display an error message.
               Message.Text = "Command name not recogized.";
               break; 

         }

      }

      void Sort_List(string commandArgument)
      {

         switch(commandArgument)
         {

            case "Ascending":
 
               // Insert code to sort the list in ascending order here.
               Message.Text = "You clicked the Sort Ascending button.";
               break;

            case "Descending":
              
               // Insert code to sort the list in descending order here.
               Message.Text = "You clicked the Sort Descending button.";
               break;

            default:
        
               // The command argument is not recognized. Display an error message.
               Message.Text = "Command argument not recogized.";
               break;

         }

      }

   </script>

</head>
 
<body>

   <form id="form1" runat="server">

      <h3>Button CommandName Example</h3>

      Click on one of the command buttons.

      <br /><br />
 
      <asp:Button id="Button1"
           Text="Sort Ascending"
           CommandName="Sort"
           CommandArgument="Ascending"
           OnCommand="CommandBtn_Click" 
           runat="server"/>

      &nbsp;

      <asp:Button id="Button2"
           Text="Sort Descending"
           CommandName="Sort"
           CommandArgument="Descending"
           OnCommand="CommandBtn_Click" 
           runat="server"/>

      <br /><br />

      <asp:Button id="Button3"
           Text="Submit"
           CommandName="Submit"
           OnCommand="CommandBtn_Click" 
           runat="server"/>

      &nbsp;

      <asp:Button id="Button4"
           Text="Unknown Command Name"
           CommandName="UnknownName"
           CommandArgument="UnknownArgument"
           OnCommand="CommandBtn_Click" 
           runat="server"/>

      &nbsp;

      <asp:Button id="Button5"
           Text="Submit Unknown Command Argument"
           CommandName="Submit"
           CommandArgument="UnknownArgument"
           OnCommand="CommandBtn_Click" 
           runat="server"/>
       
      <br /><br />

      <asp:Label id="Message" 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">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Button CommandName Example</title>
<script runat="server">

      Sub CommandBtn_Click(sender As Object, e As CommandEventArgs) 

         Select e.CommandName

            Case "Sort"

               ' Call the method to sort the list.
               Sort_List(CType(e.CommandArgument, String))

            Case "Submit"

               ' Display a message for the Submit button being clicked.
               Message.Text = "You clicked the Submit button"

               ' Test whether the command argument is an empty string ("").
               If CType(e.CommandArgument , String) = "" Then
              
                  ' End the message.
                  Message.Text &= "."
               
               Else
               
                  ' Display an error message for the command argument. 
                  Message.Text &= ", however the command argument is not recogized."
               
               End If                

            Case Else

               ' The command name is not recognized. Display an error message.
               Message.Text = "Command name not recogized."

         End Select

      End Sub

      Sub Sort_List(commandArgument As String)

         Select commandArgument

            Case "Ascending"
 
               ' Insert code to sort the list in ascending order here.
               Message.Text = "You clicked the Sort Ascending button."

            Case "Descending"
              
               ' Insert code to sort the list in descending order here.
               Message.Text = "You clicked the Sort Descending button."

            Case Else
        
               ' The command argument is not recognized. Display an error message.
               Message.Text = "Command argument not recogized."

         End Select

      End Sub

   </script>

</head>
 
<body>

   <form id="form1" runat="server">

      <h3>Button CommandName Example</h3>

      Click on one of the command buttons.

      <br /><br />
 
      <asp:Button id="Button1"
           Text="Sort Ascending"
           CommandName="Sort"
           CommandArgument="Ascending"
           OnCommand="CommandBtn_Click" 
           runat="server"/>

      &nbsp;

      <asp:Button id="Button2"
           Text="Sort Descending"
           CommandName="Sort"
           CommandArgument="Descending"
           OnCommand="CommandBtn_Click" 
           runat="server"/>

      <br /><br />

      <asp:Button id="Button3"
           Text="Submit"
           CommandName="Submit"
           OnCommand="CommandBtn_Click" 
           runat="server"/>

      &nbsp;

      <asp:Button id="Button4"
           Text="Unknown Command Name"
           CommandName="UnknownName"
           CommandArgument="UnknownArgument"
           OnCommand="CommandBtn_Click" 
           runat="server"/>

      &nbsp;

      <asp:Button id="Button5"
           Text="Submit Unknown Command Argument"
           CommandName="Submit"
           CommandArgument="UnknownArgument"
           OnCommand="CommandBtn_Click" 
           runat="server"/>
       
      <br /><br />

      <asp:Label id="Message" runat="server"/>
 
   </form>
 
</body>
</html>

Poniższy przykład kodu ilustruje sposób określania programu obsługi zdarzeń i programistycznego dodawania go do zdarzenia w Page_Load metodzie.The following code example demonstrates how to specify the event handler and programmatically add it to the event in the Page_Load method.

<%@ 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">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Button CommandName Example</title>
<script runat="server">

      void CommandBtn_Click(Object sender, CommandEventArgs e) 
      {

         switch(e.CommandName)
         {

            case "Sort":

               // Call the method to sort the list.
               Sort_List((String)e.CommandArgument);
               break;

            case "Submit":

               // Display a message for the Submit button being clicked.
               Message.Text = "You clicked the <b>Submit</b> button";

               // Test whether the Command Argument is an empty string ("").
               if((String)e.CommandArgument == "")
               {
                  // End the message.
                  Message.Text += ".";
               }
               else
               {
                  // Display an error message for the command argument. 
                  Message.Text += ", but the command argument is not recogized.";
               }                
               break;

            default:

               // The command name is not recognized. Display an error message.
               Message.Text = "Command name not recogized.";
               break; 

         }

      }

      void Sort_List(string commandArgument)
      {

         switch(commandArgument)
         {

            case "Ascending":
 
               // Insert code to sort the list in ascending order here.
               Message.Text = "You clicked the <b>Sort Ascending</b> button.";
               break;

            case "Descending":
              
               // Insert code to sort the list in descending order here.
               Message.Text = "You clicked the <b>Sort Descending</b> button.";
               break;

            default:
        
               // The command argument is not recognized. Display an error message.
               Message.Text = "Command argument not recogized.";
               break;

         }

      }

      void Page_Load(Object sender, EventArgs e)
      {

         // Manually register the event-handling method for the Command  
         // event of the Button controls.
         Button1.Command += new CommandEventHandler(this.CommandBtn_Click);
         Button2.Command += new CommandEventHandler(this.CommandBtn_Click);
         Button3.Command += new CommandEventHandler(this.CommandBtn_Click);
         Button4.Command += new CommandEventHandler(this.CommandBtn_Click);
         Button5.Command += new CommandEventHandler(this.CommandBtn_Click);

      }

   </script>

</head>
 
<body>

   <form id="form1" runat="server">

      <h3>Button CommandName Example</h3>

      Click one of the command buttons.

      <br /><br />
 
      <asp:Button id="Button1"
           Text="Sort Ascending"
           CommandName="Sort"
           CommandArgument="Ascending"
           runat="server"/>

      &nbsp;

      <asp:Button id="Button2"
           Text="Sort Descending"
           CommandName="Sort"
           CommandArgument="Descending"
           runat="server"/>

      <br /><br />

      <asp:Button id="Button3"
           Text="Submit"
           CommandName="Submit"
           runat="server"/>

      &nbsp;

      <asp:Button id="Button4"
           Text="Unknown Command Name"
           CommandName="UnknownName"
           CommandArgument="UnknownArgument"
           runat="server"/>

      &nbsp;

      <asp:Button id="Button5"
           Text="Submit Unknown Command Argument"
           CommandName="Submit"
           CommandArgument="UnknownArgument"
           runat="server"/>
       
      <br /><br />

      <asp:Label id="Message" 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">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Button CommandName Example</title>
<script runat="server">

      Sub CommandBtn_Click(sender As Object, e As CommandEventArgs) 

         Select e.CommandName

            Case "Sort"

               ' Call the method to sort the list.
               Sort_List(CType(e.CommandArgument, String))

            Case "Submit"

               ' Display a message for the Submit button being clicked.
               Message.Text = "You clicked the <b>Submit</b> button"

               ' Test whether the Command Argument is an empty string ("").
               If CType(e.CommandArgument , String) = "" Then
              
                  ' End the message.
                  Message.Text &= "."
               
               Else
               
                  ' Display an error message for the command argument. 
                  Message.Text &= ", but the command argument is not recogized."
               
               End If                

            Case Else

               ' The command name is not recognized. Display an error message.
               Message.Text = "Command name not recogized."

         End Select

      End Sub

      Sub Sort_List(commandArgument As String)

         Select commandArgument

            Case "Ascending"
 
               ' Insert code to sort the list in ascending order here.
               Message.Text = "You clicked the <b>Sort Ascending</b> button."

            Case "Descending"
              
               ' Insert code to sort the list in descending order here.
               Message.Text = "You clicked the <b>Sort Descending</b> button."

            Case Else
        
               ' The command argument is not recognized. Display an error message.
               Message.Text = "Command argument not recogized."

         End Select

      End Sub

      Sub Page_Load(sender As Object, e As EventArgs)

         ' Manually register the event-handling method for the Command  
         ' event of the Button controls.
         AddHandler Button1.Command, AddressOf CommandBtn_Click
         AddHandler Button2.Command, AddressOf CommandBtn_Click
         AddHandler Button3.Command, AddressOf CommandBtn_Click
         AddHandler Button4.Command, AddressOf CommandBtn_Click
         AddHandler Button5.Command, AddressOf CommandBtn_Click

      End Sub

   </script>

</head>
 
<body>

   <form id="form1" runat="server">

      <h3>Button CommandName Example</h3>

      Click one of the command buttons.

      <br /><br />
 
      <asp:Button id="Button1"
           Text="Sort Ascending"
           CommandName="Sort"
           CommandArgument="Ascending"
           runat="server"/>

      &nbsp;

      <asp:Button id="Button2"
           Text="Sort Descending"
           CommandName="Sort"
           CommandArgument="Descending"
           runat="server"/>

      <br /><br />

      <asp:Button id="Button3"
           Text="Submit"
           CommandName="Submit"
           runat="server"/>

      &nbsp;

      <asp:Button id="Button4"
           Text="Unknown Command Name"
           CommandName="UnknownName"
           CommandArgument="UnknownArgument"
           runat="server"/>

      &nbsp;

      <asp:Button id="Button5"
           Text="Submit Unknown Command Argument"
           CommandName="Submit"
           CommandArgument="UnknownArgument"
           runat="server"/>
       
      <br /><br />

      <asp:Label id="Message" runat="server"/>
 
   </form>
 
</body>
</html>

Uwagi

CommandZdarzenie jest zgłaszane Button , gdy ImageButton LinkButton zostanie kliknięta kontrolka, lub.The Command event is raised when a Button, ImageButton, or LinkButton control is clicked.

Podczas tworzenia CommandEventHandler delegata należy określić metodę, która będzie obsługiwać zdarzenie.When you create a CommandEventHandler delegate, you identify the method that will handle the event. Aby skojarzyć zdarzenie z programem obsługi zdarzeń, Dodaj wystąpienie delegata do zdarzenia.To associate the event with your event handler, add an instance of the delegate to the event. Program obsługi zdarzeń jest wywoływany przy każdym wystąpieniu zdarzenia, o ile nie usunięto delegata.The event handler is called whenever the event occurs, unless you remove the delegate. Aby uzyskać więcej informacji na temat delegatów obsługi zdarzeń, zobacz temat Obsługa iwywoływanie zdarzeń.For more information about event handler delegates, see Handling and Raising Events.

Metody rozszerzania

GetMethodInfo(Delegate)

Pobiera obiekt, który reprezentuje metodę reprezentowaną przez określony delegat.Gets an object that represents the method represented by the specified delegate.

Dotyczy

Zobacz też