1
using
System;
2
using
System.ComponentModel;
3
using
System.Windows.Forms;
4
5
namespace
WindowsFormsApplication1
6
{
7
public partial class Form1 : Form
8
{
9 public delegate void ActionEventHandler(object sender, ActionCancelEventArgs ev);//声明一个delegate
10 public static event ActionEventHandler Action;//声明一个名为Action的事件
11
12 string _time = "";
13
14 public Form1()
15 {
16 InitializeComponent();
17 Form1.Action += new ActionEventHandler(Form1_Action);//为事件Action增加处理程序(即通过ActionEventHandler这个delegate来调用Form1_Action)
18
}
19
20 private void Form1_Action(object sender, ActionCancelEventArgs ev) //这里的方法签名必须与ActionEventHandler的声明签名相同
21 {
22 ev.Cancel = DoAction();//调用DoAction，根据当前时间是否超过30秒，决定是否取消事件(小于30秒取消，反之继续)
23 if (ev.Cancel)
24 {
25 ev.Message = "当前时间小于30秒，事件被取消"; //如果取消，设置ev的Message属性
26 }
27 }
28
29 /// <summary>
30 /// 判断当前时间是否超过30秒
31 /// </summary>
32 /// <returns>小于30秒，返回true，反之返回false</returns>
33 private bool DoAction()
34 {
35 bool retVal = false;
36 DateTime tm = DateTime.Now;
37
38 if (tm.Second < 30)
39 {
40 _time = "";
41 retVal = true;
42 }
43 else
44 {
45 _time = "事件被触发于 " + DateTime.Now.ToLongTimeString();
46 }
47
48 return retVal;
49 }
50
51 /// <summary>
52 /// 声明一个当前时间的属性
53 /// </summary>
54 public string TimeString
55 {
56 get { return _time; }
57 }
58
59 protected void OnAction(object sender, ActionCancelEventArgs ev)
60 {
61 if (Action!=null)//如果有人订阅了Action事件
62 {
63 Action(sender, ev);//则事件触发
64 }
65 }
66
67 /// <summary>
68 /// 通过按钮来激发事件
69 /// </summary>
70 /// <param name="sender"></param>
71 /// <param name="e"></param>
72 private void btnRaise_Click(object sender, EventArgs e)
73 {
74 ActionCancelEventArgs cancelEvent = new ActionCancelEventArgs();//生成一个ActionCancelEventArgs的实例
75 OnAction(this, cancelEvent);//激发事件
76 if (cancelEvent.Cancel)//如果事件被取消，则显示Message
77 {
78 lblInfo.Text = cancelEvent.Message;
79 }
80 else//反之显示当前时间
81 {
82 lblInfo.Text = this.TimeString;
83 }
84 }
85 }
86
87 public class ActionCancelEventArgs: CancelEventArgs
88 {
89 string _msg = "";
90
91 //定义一个Message属性
92 public string Message
93 {
94 get { return _msg; }
95 set { _msg = value;}
96 }
97
98 }
99
}
100
using
System;2
using
System.ComponentModel;3
using
System.Windows.Forms;4
5
namespace
WindowsFormsApplication16
{
7
public partial class Form1 : Form8
{9
public delegate void ActionEventHandler(object sender, ActionCancelEventArgs ev);//声明一个delegate10
public static event ActionEventHandler Action;//声明一个名为Action的事件11
12
string _time = "";13
14
public Form1()15
{16
InitializeComponent();17
Form1.Action += new ActionEventHandler(Form1_Action);//为事件Action增加处理程序(即通过ActionEventHandler这个delegate来调用Form1_Action)18
}19
20
private void Form1_Action(object sender, ActionCancelEventArgs ev) //这里的方法签名必须与ActionEventHandler的声明签名相同21
{22
ev.Cancel = DoAction();//调用DoAction，根据当前时间是否超过30秒，决定是否取消事件(小于30秒取消，反之继续)23
if (ev.Cancel) 24
{25
ev.Message = "当前时间小于30秒，事件被取消"; //如果取消，设置ev的Message属性 26
}27
}28
29
/// <summary>30
/// 判断当前时间是否超过30秒31
/// </summary>32
/// <returns>小于30秒，返回true，反之返回false</returns>33
private bool DoAction() 34
{35
bool retVal = false;36
DateTime tm = DateTime.Now;37
38
if (tm.Second < 30)39
{40
_time = "";41
retVal = true;42
}43
else 44
{45
_time = "事件被触发于 " + DateTime.Now.ToLongTimeString();46
}47
48
return retVal;49
}50
51
/// <summary>52
/// 声明一个当前时间的属性53
/// </summary>54
public string TimeString 55
{56
get { return _time; }57
}58
59
protected void OnAction(object sender, ActionCancelEventArgs ev) 60
{61
if (Action!=null)//如果有人订阅了Action事件62
{63
Action(sender, ev);//则事件触发64
}65
}66
67
/// <summary>68
/// 通过按钮来激发事件69
/// </summary>70
/// <param name="sender"></param>71
/// <param name="e"></param>72
private void btnRaise_Click(object sender, EventArgs e)73
{74
ActionCancelEventArgs cancelEvent = new ActionCancelEventArgs();//生成一个ActionCancelEventArgs的实例75
OnAction(this, cancelEvent);//激发事件76
if (cancelEvent.Cancel)//如果事件被取消，则显示Message77
{78
lblInfo.Text = cancelEvent.Message;79
}80
else//反之显示当前时间81
{82
lblInfo.Text = this.TimeString;83
}84
}85
}86
87
public class ActionCancelEventArgs: CancelEventArgs 88
{89
string _msg = "";90
91
//定义一个Message属性92
public string Message 93
{94
get { return _msg; }95
set { _msg = value;}96
}97
98
}99
}
100
