EventArgs 类

参考

定义

命名空间:: System

程序集:: mscorlib.dll, System.Runtime.dll

程序集:: netstandard.dll, System.Runtime.dll

程序集:: System.Runtime.dll

程序集:: mscorlib.dll

程序集:: netstandard.dll

Source:: EventArgs.cs

Source:: EventArgs.cs

Source:: EventArgs.cs

重要

一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。

表示包含事件数据的类的基类，并提供用于不包含事件数据的事件的值。

public ref class EventArgs

public class EventArgs

[System.Serializable]
public class EventArgs

[System.Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public class EventArgs

type EventArgs = class

[<System.Serializable>]
type EventArgs = class

[<System.Serializable>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type EventArgs = class

Public Class EventArgs

继承: Object
EventArgs

派生: Microsoft.VisualBasic.ApplicationServices.ApplyApplicationDefaultsEventArgs

Microsoft.VisualBasic.ApplicationServices.StartupNextInstanceEventArgs

Microsoft.VisualBasic.Devices.NetworkAvailableEventArgs

Microsoft.Win32.PowerModeChangedEventArgs

Microsoft.Win32.SessionEndedEventArgs

更多…

属性: SerializableAttribute ComVisibleAttribute

示例

以下示例演示派生自 EventArgs 类的名为 ThresholdReachedEventArgs 的自定义事件数据类。事件数据类的实例将传递给事件的事件处理程序 ThresholdReached 。

using namespace System;

public ref class ThresholdReachedEventArgs : public EventArgs
{
   public:
      property int Threshold;
      property DateTime TimeReached;
};

public ref class Counter
{
   private:
      int threshold;
      int total;

   public:
      Counter() {};

      Counter(int passedThreshold)
      {
         threshold = passedThreshold;
      }

      void Add(int x)
      {
          total += x;
          if (total >= threshold) {
             ThresholdReachedEventArgs^ args = gcnew ThresholdReachedEventArgs();
             args->Threshold = threshold;
             args->TimeReached = DateTime::Now;
             OnThresholdReached(args);
          }
      }

      event EventHandler<ThresholdReachedEventArgs^>^ ThresholdReached;

   protected:
      virtual void OnThresholdReached(ThresholdReachedEventArgs^ e)
      {
         ThresholdReached(this, e);
      }
};

public ref class SampleHandler
{
   public:
      static void c_ThresholdReached(Object^ sender, ThresholdReachedEventArgs^ e)
      {
         Console::WriteLine("The threshold of {0} was reached at {1}.",
                            e->Threshold,  e->TimeReached);
         Environment::Exit(0);
      }
};

void main()
{
   Counter^ c = gcnew Counter((gcnew Random())->Next(10));
   c->ThresholdReached += gcnew EventHandler<ThresholdReachedEventArgs^>(SampleHandler::c_ThresholdReached);

   Console::WriteLine("press 'a' key to increase total");
   while (Console::ReadKey(true).KeyChar == 'a') {
      Console::WriteLine("adding one");
      c->Add(1);
   }
}

using System;

namespace ConsoleApplication3
{
    public class Program3
    {
        public static void Main()
        {
            Counter c = new(new Random().Next(10));
            c.ThresholdReached += c_ThresholdReached;

            Console.WriteLine("press 'a' key to increase total");
            while (Console.ReadKey(true).KeyChar == 'a')
            {
                Console.WriteLine("adding one");
                c.Add(1);
            }
        }

        static void c_ThresholdReached(object? sender, ThresholdReachedEventArgs e)
        {
            Console.WriteLine("The threshold of {0} was reached at {1}.", e.Threshold,  e.TimeReached);
            Environment.Exit(0);
        }
    }

    class Counter
    {
        private readonly int _threshold;
        private int _total;

        public Counter(int passedThreshold)
        {
            _threshold = passedThreshold;
        }

        public void Add(int x)
        {
            _total += x;
            if (_total >= _threshold)
            {
                ThresholdReachedEventArgs args = new()
                {
                    Threshold = _threshold,
                    TimeReached = DateTime.Now
                };
                OnThresholdReached(args);
            }
        }

        protected virtual void OnThresholdReached(ThresholdReachedEventArgs e)
        {
            ThresholdReached?.Invoke(this, e);
        }

        public event EventHandler<ThresholdReachedEventArgs>? ThresholdReached;
    }

    public class ThresholdReachedEventArgs : EventArgs
    {
        public int Threshold { get; set; }
        public DateTime TimeReached { get; set; }
    }
}

open System

type ThresholdReachedEventArgs(threshold, timeReached) =
    inherit EventArgs()
    member _.Threshold = threshold
    member _.TimeReached = timeReached

type Counter(threshold) =
    let mutable total = 0

    let thresholdReached = Event<_>()

    member this.Add(x) =
        total <- total + x
        if total >= threshold then
            let args = ThresholdReachedEventArgs(threshold, DateTime.Now)
            thresholdReached.Trigger(this, args)

    [<CLIEvent>]
    member _.ThresholdReached = thresholdReached.Publish

let c_ThresholdReached(sender, e: ThresholdReachedEventArgs) =
    printfn $"The threshold of {e.Threshold} was reached at {e.TimeReached}."
    exit 0

let c = Counter(Random().Next 10)
c.ThresholdReached.Add c_ThresholdReached

printfn "press 'a' key to increase total"
while Console.ReadKey(true).KeyChar = 'a' do
    printfn "adding one"
    c.Add 1

Module Module1

    Sub Main()
        Dim c As Counter = New Counter(New Random().Next(10))
        AddHandler c.ThresholdReached, AddressOf c_ThresholdReached

        Console.WriteLine("press 'a' key to increase total")
        While Console.ReadKey(True).KeyChar = "a"
            Console.WriteLine("adding one")
            c.Add(1)
        End While
    End Sub

    Sub c_ThresholdReached(sender As Object, e As ThresholdReachedEventArgs)
        Console.WriteLine("The threshold of {0} was reached at {1}.", e.Threshold, e.TimeReached)
        Environment.Exit(0)
    End Sub
End Module

Class Counter
    Private threshold As Integer
    Private total As Integer

    Public Sub New(passedThreshold As Integer)
        threshold = passedThreshold
    End Sub

    Public Sub Add(x As Integer)
        total = total + x
        If (total >= threshold) Then
            Dim args As ThresholdReachedEventArgs = New ThresholdReachedEventArgs()
            args.Threshold = threshold
            args.TimeReached = DateTime.Now
            OnThresholdReached(args)
        End If
    End Sub

    Protected Overridable Sub OnThresholdReached(e As ThresholdReachedEventArgs)
        RaiseEvent ThresholdReached(Me, e)
    End Sub

    Public Event ThresholdReached As EventHandler(Of ThresholdReachedEventArgs)
End Class

Class ThresholdReachedEventArgs
    Inherits EventArgs

    Public Property Threshold As Integer
    Public Property TimeReached As DateTime
End Class

注解

此类用作表示事件数据的所有类的基类。例如， System.AssemblyLoadEventArgs 类派生自 EventArgs ，用于保存程序集加载事件的数据。若要创建自定义事件数据类，请创建派生自类 EventArgs 的类，并提供用于存储必要数据的属性。自定义事件数据类的名称应以结尾 EventArgs。

若要传递不包含任何数据的对象，请使用 Empty 字段。

有关事件的详细信息，请参阅处理和引发事件一文。

构造函数

EventArgs()

初始化 EventArgs 类的新实例。

字段

Empty

提供要用于没有事件数据的事件的值。

方法

Equals(Object)	确定指定对象是否等于当前对象。 (继承自 Object)
GetHashCode()	作为默认哈希函数。 (继承自 Object)
GetType()	获取当前实例的 Type。 (继承自 Object)
MemberwiseClone()	创建当前 Object 的浅表副本。 (继承自 Object)
ToString()	返回表示当前对象的字符串。 (继承自 Object)

适用于

产品	版本
.NET	Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9, 10
.NET Framework	1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard	1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2.0, 2.1
UWP	10.0

通过

EventArgs 类

定义

示例

注解

构造函数

字段

方法

适用于

另请参阅

其他资源