KeyEventArgs 类
**命名空间:**System.Windows.Forms
**程序集:**System.Windows.Forms（在 system.windows.forms.dll 中）
语法
声明
<ComVisibleAttribute(True)> _
Public Class KeyEventArgs
Inherits EventArgs
用法
Dim instance As KeyEventArgs
[ComVisibleAttribute(true)]
public class KeyEventArgs : EventArgs
[ComVisibleAttribute(true)]
public ref class KeyEventArgs : public EventArgs
/** @attribute ComVisibleAttribute(true) */
public class KeyEventArgs extends EventArgs
ComVisibleAttribute(true)
public class KeyEventArgs extends EventArgs
备注
KeyEventArgs（指定用户曾按下的键以及是否曾同时按下修改键：Ctrl、Alt 和 Shift 键）随着 KeyDown 或 KeyUp 事件的每一次发生而被传递。
当用户按下任意键时，发生 KeyDown 事件。当用户释放该键时，发生 KeyUp 事件。如果键被按住，那么，每次键重复时，KeyDown 事件都重复发生；但当用户释放该键时，仅发生一次 KeyUp 事件。
按下某个键时，还发生 KeyPress 事件。KeyPressEventArgs 随着 KeyPress 事件的每一次发生而被传递，并指定每次按键结果所形成的字符。
有关事件模型的信息，请参见 事件和委托。
示例
下面的代码示例演示如何检测按键的状态。
' This example demonstrates how to use the KeyDown event with the Help class to display
' pop-up style help to the user of the application. The example filters for all variations
' of pressing the F1 key with a modifier key by using the KeyEventArgs properties passed
' to the event-handler method.
' When the user presses any variation of F1 that includes any keyboard modifier, the Help
' class displays a pop-up window, similar to a ToolTip, near the control. If the user presses
' ALT + F2, a different Help pop-up is displayed with additional information. This example assumes
' that a TextBox control, named textBox1, has been added to the form and its KeyDown
' event has been contected to this event-handler method.
Private Sub textBox1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles textBox1.KeyDown
' Determine whether the key entered is the F1 key. If it is, display Help.
If e.KeyCode = Keys.F1 AndAlso (e.Alt OrElse e.Control OrElse e.Shift) Then
' Display a pop-up Help topic to assist the user.
Help.ShowPopup(textBox1, "Enter your name.", New Point(textBox1.Bottom, textBox1.Right))
ElseIf e.KeyCode = Keys.F2 AndAlso e.Modifiers = Keys.Alt Then
' Display a pop-up Help topic to provide additional assistance to the user.
Help.ShowPopup(textBox1, "Enter your first name followed by your last name. Middle name is optional.", _
New Point(textBox1.Top, Me.textBox1.Left))
End If
End Sub 'textBox1_KeyDown
// This example demonstrates how to use the KeyDown event with the Help class to display
// pop-up style help to the user of the application. The example filters for all variations
// of pressing the F1 key with a modifier key by using the KeyEventArgs properties passed
// to the event-handler method.
// When the user presses any variation of F1 that includes any keyboard modifier, the Help
// class displays a pop-up window, similar to a ToolTip, near the control. If the user presses
// ALT + F2, a different Help pop-up is displayed with additional information. This example assumes
// that a tTextBox control, named textBox1, has been added to the form and its KeyDown
// event has been contected to this event-handler method.
private void textBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
// Determine whether the key entered is the F1 key. If it is, display Help.
if(e.KeyCode == Keys.F1 && (e.Alt || e.Control || e.Shift))
{
// Display a pop-up Help topic to assist the user.
Help.ShowPopup(textBox1, "Enter your name.", new Point(textBox1.Bottom, textBox1.Right));
}
else if(e.KeyCode == Keys.F2 && e.Modifiers == Keys.Alt)
{
// Display a pop-up Help topic to provide additional assistance to the user.
Help.ShowPopup(textBox1, "Enter your first name followed by your last name. Middle name is optional.",
new Point(textBox1.Top, this.textBox1.Left));
}
}
// This example demonstrates how to use the KeyDown event with the Help class to display
// pop-up style help to the user of the application. The example filters for all variations
// of pressing the F1 key with a modifier key by using the KeyEventArgs properties passed
// to the event handling method.
// When the user presses any variation of F1 that includes any keyboard modifier, the Help
// class displays a pop-up window, similar to a ToolTip, near the control. If the user presses
// ALT + F2, a different Help pop-up is displayed with additional information. This example assumes
// that a tTextBox control, named textBox1, has been added to the form and its KeyDown
// event has been contected to this event handling method.
private:
void textBox1_KeyDown( Object^ /*sender*/, System::Windows::Forms::KeyEventArgs^ e )
{
// Determine whether the key entered is the F1 key. If it is, display Help.
if ( e->KeyCode == Keys::F1 && (e->Alt || e->Control || e->Shift) )
{
// Display a pop-up Help topic to assist the user.
Help::ShowPopup( textBox1, "Enter your name.", Point(textBox1->Bottom,textBox1->Right) );
}
else
if ( e->KeyCode == Keys::F2 && e->Modifiers == Keys::Alt )
{
// Display a pop-up Help topic to provide additional assistance to the user.
Help::ShowPopup( textBox1, "Enter your first name followed by your last name. Middle name is optional.",
Point(textBox1->Top,this->textBox1->Left) );
}
}
// This example demonstrates how to use the KeyDown event with the Help
// class to display pop-up style help to the user of the application.
// The example filters for all variations of pressing the F1 key with
// a modifier key by using the KeyEventArgs properties passed to the
// event handling method.When the user presses any variation of F1 that
// includes any keyboard modifier, the Help class displays a pop-up window,
// similar to a ToolTip, near the control. If the user presses ALT + F2,
// a different Help pop-up is displayed with additional information.
// This example assumes that a tTextBox control, named textBox1, has been
// added to the form and its KeyDown event has been contected to this
// event handling method.
private void textBox1_KeyDown(Object sender,
System.Windows.Forms.KeyEventArgs e)
{
// Determine whether the key entered is the F1 key.
//If it is, display Help.
if (e.get_KeyCode().Equals(Keys.F1) && (e.get_Alt() || e.get_Control()
|| e.get_Shift())) {
// Display a pop-up Help topic to assist the user.
Help.ShowPopup(textBox1, "Enter your name.", new Point(textBox1.
get_Bottom(), textBox1.get_Right()));
}
else {
if (e.get_KeyCode().Equals(Keys.F2) && e.get_Modifiers().
Equals(Keys.Alt)) {
// Display a pop-up Help topic to provide additional assistance
// to the user.
Help.ShowPopup(textBox1, "Enter your first name followed by"
+ " your last name.Middle name is optional.",new Point(
textBox1.get_Top(), this.textBox1.get_Left()));
}
}
} //textBox1_KeyDown
} //Form1
Private Sub treeView1_KeyDown(sender As Object, _
e As KeyEventArgs) Handles treeView1.KeyDown
' If the 'Alt' and 'E' keys are pressed,
' allow the user to edit the TreeNode label.
If e.Alt And e.KeyCode = Keys.E Then
treeView1.LabelEdit = True
' If there is a TreeNode under the mose cursor, begin editing.
Dim editNode As TreeNode = treeView1.GetNodeAt( _
treeView1.PointToClient(Control.MousePosition))
If Not (editNode Is Nothing) Then
editNode.BeginEdit()
End If
End If
End Sub
Private Sub treeView1_AfterLabelEdit(sender As Object, _
e As NodeLabelEditEventArgs) Handles treeView1.AfterLabelEdit
' Disable the ability to edit the TreeNode labels.
treeView1.LabelEdit = False
End Sub
private void treeView1_KeyDown(object sender, KeyEventArgs e)
{
/* If the 'Alt' and 'E' keys are pressed,
* allow the user to edit the TreeNode label. */
if(e.Alt && e.KeyCode == Keys.E)
{
treeView1.LabelEdit = true;
// If there is a TreeNode under the mose cursor, begin editing.
TreeNode editNode = treeView1.GetNodeAt(
treeView1.PointToClient(Control.MousePosition));
if(editNode != null)
{
editNode.BeginEdit();
}
}
}
private void treeView1_AfterLabelEdit(object sender, NodeLabelEditEventArgs e)
{
// Disable the ability to edit the TreeNode labels.
treeView1.LabelEdit = false;
}
private:
void treeView1_KeyDown( Object^ /*sender*/, KeyEventArgs^ e )
{
/* If the 'Alt' and 'E' keys are pressed,
* allow the user to edit the TreeNode label. */
if ( e->Alt && e->KeyCode == Keys::E )
{
treeView1->LabelEdit = true;
// If there is a TreeNode under the mose cursor, begin editing.
TreeNode^ editNode = treeView1->GetNodeAt( treeView1->PointToClient( Control::MousePosition ) );
if ( editNode != nullptr )
{
editNode->BeginEdit();
}
}
}
void treeView1_AfterLabelEdit( Object^ /*sender*/, NodeLabelEditEventArgs^ /*e*/ )
{
// Disable the ability to edit the TreeNode labels.
treeView1->LabelEdit = false;
}
private void treeView1_KeyDown(Object sender, KeyEventArgs e)
{
/* If the 'Alt' and 'E' keys are pressed,
allow the user to edit the TreeNode label.
*/
if (e.get_Alt() && e.get_KeyCode() == Keys.E) {
treeView1.set_LabelEdit(true);
// If there is a TreeNode under the mose cursor, begin editing.
TreeNode editNode = treeView1.GetNodeAt(treeView1.PointToClient(
Control.get_MousePosition()));
if (editNode != null) {
editNode.BeginEdit();
}
}
} //treeView1_KeyDown
private void treeView1_AfterLabelEdit(Object sender,
NodeLabelEditEventArgs e)
{
// Disable the ability to edit the TreeNode labels.
treeView1.set_LabelEdit(false);
} //treeView1_AfterLabelEdit
' Boolean flag used to determine when a character other than a number is entered.
Private nonNumberEntered As Boolean = False
' Handle the KeyDown event to determine the type of character entered into the control.
Private Sub textBox1_KeyDown(sender As Object, e As System.Windows.Forms.KeyEventArgs) _
Handles textBox1.KeyDown
' Initialize the flag to false.
nonNumberEntered = False
' Determine whether the keystroke is a number from the top of the keyboard.
If e.KeyCode < Keys.D0 OrElse e.KeyCode > Keys.D9 Then
' Determine whether the keystroke is a number from the keypad.
If e.KeyCode < Keys.NumPad0 OrElse e.KeyCode > Keys.NumPad9 Then
' Determine whether the keystroke is a backspace.
If e.KeyCode <> Keys.Back Then
' A non-numerical keystroke was pressed.
' Set the flag to true and evaluate in KeyPress event.
nonNumberEntered = True
End If
End If
End If
End Sub 'textBox1_KeyDown
' This event occurs after the KeyDown event and can be used
' to prevent characters from entering the control.
Private Sub textBox1_KeyPress(sender As Object, e As System.Windows.Forms.KeyPressEventArgs) _
Handles textBox1.KeyPress
' Check for the flag being set in the KeyDown event.
If nonNumberEntered = True Then
' Stop the character from being entered into the control since it is non-numerical.
e.Handled = True
End If
End Sub 'textBox1_KeyPress
End Class 'Form1
// Boolean flag used to determine when a character other than a number is entered.
private bool nonNumberEntered = false;
// Handle the KeyDown event to determine the type of character entered into the control.
private void textBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
// Initialize the flag to false.
nonNumberEntered = false;
// Determine whether the keystroke is a number from the top of the keyboard.
if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9)
{
// Determine whether the keystroke is a number from the keypad.
if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)
{
// Determine whether the keystroke is a backspace.
if(e.KeyCode != Keys.Back)
{
// A non-numerical keystroke was pressed.
// Set the flag to true and evaluate in KeyPress event.
nonNumberEntered = true;
}
}
}
}
// This event occurs after the KeyDown event and can be used to prevent
// characters from entering the control.
private void textBox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
// Check for the flag being set in the KeyDown event.
if (nonNumberEntered == true)
{
// Stop the character from being entered into the control since it is non-numerical.
e.Handled = true;
}
}
// Boolean flag used to determine when a character other than a number is entered.
private:
bool nonNumberEntered;
// Handle the KeyDown event to determine the type of character entered into the control.
void textBox1_KeyDown( Object^ /*sender*/, System::Windows::Forms::KeyEventArgs^ e )
{
// Initialize the flag to false.
nonNumberEntered = false;
// Determine whether the keystroke is a number from the top of the keyboard.
if ( e->KeyCode < Keys::D0 || e->KeyCode > Keys::D9 )
{
// Determine whether the keystroke is a number from the keypad.
if ( e->KeyCode < Keys::NumPad0 || e->KeyCode > Keys::NumPad9 )
{
// Determine whether the keystroke is a backspace.
if ( e->KeyCode != Keys::Back )
{
// A non-numerical keystroke was pressed.
// Set the flag to true and evaluate in KeyPress event.
nonNumberEntered = true;
}
}
}
}
// This event occurs after the KeyDown event and can be used to prevent
// characters from entering the control.
void textBox1_KeyPress( Object^ /*sender*/, System::Windows::Forms::KeyPressEventArgs^ e )
{
// Check for the flag being set in the KeyDown event.
if ( nonNumberEntered == true )
{ // Stop the character from being entered into the control since it is non-numerical.
e->Handled = true;
}
}
// Boolean flag used to determine when a character other than a number
// is entered.
private boolean nonNumberEntered = false;
// Handle the KeyDown event to determine the type of character entered
// into the control.
private void textBox1_KeyDown(Object sender,
System.Windows.Forms.KeyEventArgs e)
{
// Initialize the flag to false.
nonNumberEntered = false;
// Determine whether the keystroke is a number from the top of the
// keyboard.
if ((e.get_KeyCode().CompareTo(Keys.D0)) < 0
|| (e.get_KeyCode().CompareTo(Keys.D9) > 0)) {
// Determine whether the keystroke is a number from the keypad.
if ((e.get_KeyCode().CompareTo(Keys.NumPad0) < 0
|| (e.get_KeyCode().CompareTo(Keys.NumPad9)) > 0)) {
// Determine whether the keystroke is a backspace.
if (!(e.get_KeyCode().Equals(Keys.Back))) {
// A non-numerical keystroke was pressed.
// Set the flag to true and evaluate in KeyPress event.
nonNumberEntered = true;
}
}
}
} //textBox1_KeyDown
// This event occurs after the KeyDown event and can be used to prevent
// characters from entering the control.
private void textBox1_KeyPress(Object sender, System.Windows.Forms.
KeyPressEventArgs e)
{
// Check for the flag being set in the KeyDown event.
if (nonNumberEntered == true) {
// Stop the character from being entered into the control since
// it is non-numerical.
e.set_Handled(true);
}
} //textBox1_KeyPress
继承层次结构
System.Object
System.EventArgs
System.Windows.Forms.KeyEventArgs
线程安全
此类型的任何公共静态（Visual Basic 中的 Shared）成员都是线程安全的，但不保证所有实例成员都是线程安全的。
平台
Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition
.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。
版本信息
.NET Framework
受以下版本支持：2.0、1.1、1.0
.NET Compact Framework
受以下版本支持：2.0、1.0
请参见
参考
KeyEventArgs 成员
System.Windows.Forms 命名空间
OnKeyDown
Control.KeyDown 事件
OnKeyUp
Control.KeyUp 事件
KeyPressEventArgs
OnKeyPress
Control.KeyPress 事件