C#---- 单列模式（定时器）

 // 定义计时器对象
 1  public class CountDown
 2     {
 3 
 4         private static CountDown theCountDown = null;
 5         private static readonly object _padLock = new object(); // unique object for lock
 6 
 7         private Timer timer = null; //计时器
 8         private int dt;
 9 
10         /// <summary>
11         /// decide logic
12         /// </summary>
13         public int DT
14         { 
15             get;
16             set;
17         }           
18 
19         private CountDown ()
20         {
21             timer = new Timer();
22             timer.Interval = 60000;  // 1 min to elapsed 
23             dt = 0;
24             DT = 0; 
25             timer.Elapsed += timer_Elapsed;            
26         }
27 
28        private void timer_Elapsed(object sender, ElapsedEventArgs e)
29         {
30             dt--;
31             if (dt<=0)
32             {
33                 timer.Stop();                
34             }
35             DT = dt; // update DT for logic
36         }
37 
38 
39         /// <summary>
40         /// start timer by using param to set times of loop
41         /// </summary>
42         /// <param name="times"></param>
43         public void Start(int times)
44        {
45             if (dt <=0)
46             {
47                 dt = times;
48                 timer.Start();
49             }
50           
51        }
52 
53         /// <summary>
54         /// start timer 60 times loop as default
55         /// </summary>
56         public void Start()
57         {
58             if (dt <= 0)
59             {
60                 dt = 60;
61                 timer.Start();
62             }
63 
64         }
65 
66         /// <summary>
67         /// stop  timer
68         /// </summary>
69         public void Stop()
70         {
71             timer.Stop();
72         }            
73 
74         /// <summary>
75         ///  实例化定时器
76         /// </summary>
77         /// <returns></returns>
78         public static CountDown Instance()
79         {
80             //判定对象是否实例化
81             if (null == theCountDown)
82             {
83                 lock (_padLock)// 添加线程锁
84                 {
85                     if (null == theCountDown)
86                     {
87                         theCountDown = new CountDown();
88                     }
89                 }
90 
91             }
92             return theCountDown;
93         }
94     }

 1   //实例化对象
 2                 CountDown cd = CountDown.Instance();
 3                 if (cd.DT <= 0)
 4                 {  
 7 
 8                     // TODO Something：
 9 
10                     cd.Start(60); //开始计时，设定循环次数（1小时后，才可以再次调用该逻辑）
11                 }