Timer 类
实现在用户定义的时间间隔引发事件的计时器。此计时器最宜用于 Windows 窗体应用程序中，并且必须在窗口中使用。
**命名空间:**System.Windows.Forms
**程序集:**System.Windows.Forms（在 system.windows.forms.dll 中）
语法
声明
Public Class Timer
Inherits Component
用法
Dim instance As Timer
public class Timer : Component
public ref class Timer : public Component
public class Timer extends Component
public class Timer extends Component
备注
Timer 用于以用户定义的事件间隔触发事件。Windows 计时器是为单线程环境设计的，其中，UI 线程用于执行处理。它要求用户代码有一个可用的 UI 消息泵，而且总是在同一个线程中操作，或者将调用封送到另一个线程。
使用此计时器时，请使用 Tick 事件执行轮询操作，或在指定的时间内显示启动画面。每当 Enabled 属性设置为 true 且 Interval 属性大于 0 时，将引发 Tick 事件，引发的时间间隔基于 Interval 属性设置。
此类提供用于设置时间间隔以及启动和停止计时器的方法。
提示
Windows 窗体 Timer 组件是单线程组件，精度限定为 55 毫秒。如果您需要更高精度的多线程计时器，请使用 System.Timers 命名空间中的 Timer 类。
示例
下面的示例实现简单的间隔计时器，该计时器每五秒钟发一次警报。当发生警报时，MessageBox 显示该警报已启动次数的计数，并询问用户计时器是否应继续运行。
Public Class Class1
Private Shared myTimer As New System.Windows.Forms.Timer()
Private Shared alarmCounter As Integer = 1
Private Shared exitFlag As Boolean = False
' This is the method to run when the timer is raised.
Private Shared Sub TimerEventProcessor(myObject As Object, _
myEventArgs As EventArgs)
myTimer.Stop()
' Displays a message box asking whether to continue running the timer.
If MessageBox.Show("Continue running?", "Count is: " & alarmCounter, _
MessageBoxButtons.YesNo) = DialogResult.Yes Then
' Restarts the timer and increments the counter.
alarmCounter += 1
myTimer.Enabled = True
Else
' Stops the timer.
exitFlag = True
End If
End Sub
Public Shared Sub Main()
' Adds the event and the event handler for the method that will
' process the timer event to the timer.
AddHandler myTimer.Tick, AddressOf TimerEventProcessor
' Sets the timer interval to 5 seconds.
myTimer.Interval = 5000
myTimer.Start()
' Runs the timer, and raises the event.
While exitFlag = False
' Processes all the events in the queue.
Application.DoEvents()
End While
End Sub
End Class
public class Class1 {
static System.Windows.Forms.Timer myTimer = new System.Windows.Forms.Timer();
static int alarmCounter = 1;
static bool exitFlag = false;
// This is the method to run when the timer is raised.
private static void TimerEventProcessor(Object myObject,
EventArgs myEventArgs) {
myTimer.Stop();
// Displays a message box asking whether to continue running the timer.
if(MessageBox.Show("Continue running?", "Count is: " + alarmCounter,
MessageBoxButtons.YesNo) == DialogResult.Yes) {
// Restarts the timer and increments the counter.
alarmCounter +=1;
myTimer.Enabled = true;
}
else {
// Stops the timer.
exitFlag = true;
}
}
public static int Main() {
/* Adds the event and the event handler for the method that will
process the timer event to the timer. */
myTimer.Tick += new EventHandler(TimerEventProcessor);
// Sets the timer interval to 5 seconds.
myTimer.Interval = 5000;
myTimer.Start();
// Runs the timer, and raises the event.
while(exitFlag == false) {
// Processes all the events in the queue.
Application.DoEvents();
}
return 0;
}
}
public ref class Class1
{
private:
static System::Windows::Forms::Timer^ myTimer = gcnew System::Windows::Forms::Timer;
static int alarmCounter = 1;
static bool exitFlag = false;
// This is the method to run when the timer is raised.
static void TimerEventProcessor( Object^ /*myObject*/, EventArgs^ /*myEventArgs*/ )
{
myTimer->Stop();
// Displays a message box asking whether to continue running the timer.
if ( MessageBox::Show( "Continue running?", String::Format( "Count is: {0}", alarmCounter ), MessageBoxButtons::YesNo ) == DialogResult::Yes )
{
// Restarts the timer and increments the counter.
alarmCounter += 1;
myTimer->Enabled = true;
}
else
{
// Stops the timer.
exitFlag = true;
}
}
public:
static void Main()
{
/* Adds the event and the event handler for the method that will
process the timer event to the timer. */
myTimer->Tick += gcnew EventHandler( TimerEventProcessor );
// Sets the timer interval to 5 seconds.
myTimer->Interval = 5000;
myTimer->Start();
// Runs the timer, and raises the event.
while ( exitFlag == false )
{
// Processes all the events in the queue.
Application::DoEvents();
}
}
};
int main()
{
Class1::Main();
}
public class Class1
{
private static System.Windows.Forms.Timer myTimer =
new System.Windows.Forms.Timer();
private static int alarmCounter = 1;
private static boolean exitFlag = false;
// This is the method to run when the timer is raised.
private static void TimerEventProcessor(Object myObject,
EventArgs myEventArgs)
{
myTimer.Stop();
// Displays a message box asking whether to continue running the timer.
if (MessageBox.Show("Continue running?", "Count is: "
+ alarmCounter, MessageBoxButtons.YesNo).Equals(DialogResult.Yes)) {
// Restarts the timer and increments the counter.
alarmCounter += 1;
myTimer.set_Enabled(true);
}
else {
// Stops the timer.
exitFlag = true;
}
} //TimerEventProcessor
public static void main(String[] args)
{
/* Adds the event and the event handler for the method that will
process the timer event to the timer.
*/
myTimer.add_Tick(new EventHandler(TimerEventProcessor));
// Sets the timer interval to 5 seconds.
myTimer.set_Interval(5000);
myTimer.Start();
// Runs the timer, and raises the event.
while (exitFlag == false) {
// Processes all the events in the queue.
Application.DoEvents();
}
return;
} //main
} //Class1
继承层次结构
System.Object
System.MarshalByRefObject
System.ComponentModel.Component
System.Windows.Forms.Timer
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