Button.OnCommand(CommandEventArgs) 方法

  • 参考

定义

命名空间:
System.Web.UI.WebControls
程序集:
System.Web.dll

引发 Button 控件的 Command 事件。

protected:
 virtual void OnCommand(System::Web::UI::WebControls::CommandEventArgs ^ e);
protected virtual void OnCommand (System.Web.UI.WebControls.CommandEventArgs e);
abstract member OnCommand : System.Web.UI.WebControls.CommandEventArgs -> unit
override this.OnCommand : System.Web.UI.WebControls.CommandEventArgs -> unit
Protected Overridable Sub OnCommand (e As CommandEventArgs)

参数

e
CommandEventArgs

事件数据。

示例

下面的代码示例演示如何指定和编码事件的事件处理程序， Command 以便在单击控件时 Button 对列表进行排序。 此示例使用 OnClick 控件的 Button 属性以声明方式指定事件处理程序。

<%@ 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"/>

       

      <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"/>

       

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

       

      <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"/>

       

      <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"/>

       

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

       

      <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>

下面的代码示例演示如何指定 事件处理程序，以及如何以编程方式将其添加到 方法中的 Page_Load 事件。

<%@ 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"/>

       

      <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"/>

       

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

       

      <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"/>

       

      <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"/>

       

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

       

      <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>

注解

单击 Command 控件时， Button 将引发 事件。 当命令名称（如 Sort）与 Button 控件关联时，通常使用此事件。 这允许你在网页上创建多个 Button 控件，并通过编程方式确定单击哪个 Button 控件。

备注

事件 Command 通过控件层次结构以 的形式 BubbleEvent引发。

引发事件时，将通过委托调用事件处理程序。 有关详细信息，请参阅 处理和引发事件。

OnCommand 方法还允许派生类对事件进行处理而不必附加委托。 这是在派生类中处理事件的首选技术。

继承者说明

在派生类中重写 OnCommand(CommandEventArgs) 时，一定要调用基类的 OnCommand(CommandEventArgs) 方法，以便已注册的委托对事件进行接收。

适用于

另请参阅