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C#学习基本概念之事件（五）---EventArgs

2016-11-28 16:08 507 查看

Represents
the base class for classes that contain event data, and provides a
value to use for events that do not include event data.

[SerializableAttribute]
[ComVisibleAttribute(true)]public class EventArgs

构造函数

EventArgs()

Initializes a new instance of the EventArgs class.

方法

	名称	说明
	Equals(Object)	Determines whether the specified object is equal to the current object.（继承自 Object。）
	Finalize()	Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.（继承自 Object。）
	GetHashCode()	Serves as the default hash function.（继承自 Object。）
	GetType()	Gets the Type of the current instance.（继承自 Object。）
	MemberwiseClone()	Creates a shallow copy of the current Object.（继承自 Object。）
	ToString()	Returns a string that represents the current object.（继承自 Object。）

字段

EmptyProvides a value to use with events that do not have event data

备注
This
class serves as the base class for all classes that represent event
data. For example, the T:System.AssemblyLoadEventArgs class derives from
T:System.EventArgs and is used to hold the data for assembly load
events. To create a custom event data class, create a class that derives
from the T:System.EventArgs class and provide the properties to store
the necessary data. The name of your custom event data class should end
with EventArgs.
To pass an object that does not contain any data, use the F:System.EventArgs.Empty field.
For more information about events, see the Handling and Raising Events article.

示例
The
following example shows a custom event data class named
ThresholdReachedEventArgs that derives from the T:System.EventArgs
class. An instance of the event data class is passed to the event
handler for the ThresholdReached event.

using System;
namespace ConsoleApplication1
{
class Program
{        static void Main(string[] args)
{
Counter c = new Counter(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 int threshold;
private int total;
public Counter(int passedThreshold)
{
threshold = passedThreshold;
}
public void Add(int x)
{
total += x;
if (total >= threshold)
{
ThresholdReachedEventArgs args = new ThresholdReachedEventArgs();
args.Threshold = threshold;
args.TimeReached = DateTime.Now;
OnThresholdReached(args);
}
}
protected virtual void OnThresholdReached(ThresholdReachedEventArgs e)
{
EventHandler<ThresholdReachedEventArgs> handler = ThresholdReached;
if (handler != null)
{
handler(this, e);
}
}
public event EventHandler<ThresholdReachedEventArgs> ThresholdReached;
}    public class ThresholdReachedEventArgs : EventArgs
{        public int Threshold { get; set; }
public DateTime TimeReached { get; set; }
}
}

线程安全
此类型的所有公共静态（Visual Basic 中的
已共享
在 Visual Basic 中）成员都是线程安全的。不保证所有实例成员都是线程安全的。

备注：摘自https://msdn.microsoft.com/zh-cn/library/system.eventargs.aspx

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标签： EventArgs

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