委托与事件示例

 

  1using System;
  2using System.Collections.Generic;
  3using System.Linq;
  4using System.Text;
  5using System.ComponentModel;
  6
  7namespace EventSample
  8{
  9    //定义事件参数类
 10    public class AlarmEventArgs:EventArgs 
 11    {
 12        private readonly bool  keepingSleep;
 13        private readonly int numrings;
 14
 15        //构造函数
 16        public AlarmEventArgs(bool keepingSleep, int numrings)
 17            : base()
 18        {
 19            this. keepingSleep =  keepingSleep;
 20            this.numrings = numrings;
 21        }
 22
 23         //定义属性
 24        public int NumRings
 25        {
 26            get { return numrings; }
 27        }
 28
 29        public bool KeepingSleep
 30        {
 31            get { return  keepingSleep; }
 32        }
 33
 34        public string AlarmText
 35        {
 36            get
 37            {
 38                if ( keepingSleep)
 39                {
 40                    return ("要迟到了！懒虫快起床！");
 41                }
 42                else
 43                {
 44                    return ("太阳出来啰，起床吧！");
 45                }
 46            }
 47        }
 48    }
 49
 50       //声明自定义代理类型，它的事件参数的类型为AlarmEventArgs
 51        public delegate void AlarmEventHandler(object sender, AlarmEventArgs e);
 52
 53       //包含事件和触发事件方法的类
 54        public class AlarmClock
 55        {
 56            private bool keepingSleep=false ;
 57            private int numrings=0;
 58            private bool stop=false ;
 59
 60            public bool Stop
 61            {
 62                get {return stop; }
 63                set {stop =value ;}
 64            }
 65
 66            public bool  KeepingSleep
 67            {
 68                get {return  keepingSleep; }
 69                set { keepingSleep=value ;}
 70            }
 71
 72            //声明事件，它所使用的代理类型为AlarmEventHandler
 73            public event AlarmEventHandler Alarm;
 74
 75
 76            //触发事件的方法
 77            protected virtual void OnAlarm(AlarmEventArgs e)
 78            {
 79                if (Alarm !=null )
 80                {
 81                    //通过代理调用事件处理方法
 82                    Alarm (this ,e );
 83                }
 84            }
 85
 86            //在该方法中循环调用OnAlarm方法来触发事件，直到stop字段的值为true
 87            public void Start()
 88            {
 89                for ( ; ; )
 90                {
 91                    numrings++;
 92                    if (stop)
 93                    {
 94                        break;
 95                    }
 96                    else if (KeepingSleep)
 97                    {
 98                        //程序暂停0.5秒钟
 99                        System.Threading.Thread.Sleep(500);
100                        {
101                            //创建事件参数对象实例
102                            AlarmEventArgs e = new AlarmEventArgs(KeepingSleep, numrings);
103                            OnAlarm(e);
104                            //触发事件，在事件处理方法中会相应地设置KeepingSleep和Stop字段的值（通过属性来设置）
105                        }
106                    }
107                    else
108                    {
109                        //程序暂停0.3秒
110                        System.Threading.Thread.Sleep(300);
111                        AlarmEventArgs e = new AlarmEventArgs(keepingSleep, numrings);
112                        OnAlarm(e);//触发事件
113                    }
114                }
115            }
116        }
117
118    //包含事件处理方法的类
119    public class WakeMeUp
120    {
121        //事件处理方法，在该方法中根据用户的输入来通过事件参数sender设置事件发送者属性
122        public void AlarmRing(object sender, AlarmEventArgs e)
123        {
124            Console.WriteLine(e.AlarmText + "\n");
125
126            if (!(e.KeepingSleep))
127            {
128                if (e.NumRings % 10 == 0)
129                {
130                    Console.WriteLine("继续叫你起床！(请输入Y)");
131                    Console.WriteLine("让你再睡一会儿！(请输入N)");
132                    Console.WriteLine("停止闹铃！(请输入不同于Y和N的键)");
133                    string input = Console.ReadLine();
134
135                    if (input.Equals("Y") || input.Equals("y")) return;
136                    else if (input.Equals("N") || input.Equals("n"))
137                    {
138                        //通过事件参数sender来访问触发事件的对象
139                        ((AlarmClock)sender).KeepingSleep = true;
140                        return;
141                    }
142                    else
143                    {
144                        ((AlarmClock)sender).Stop = true;
145                        return;
146                    }
147                }
148            }
149            else
150            {
151                Console.WriteLine("继续叫你起床!(请输入Y)");
152                string input = Console.ReadLine();
153                if (input.Equals("Y") || input.Equals("y")) return;
154                else
155                {
156                    ((AlarmClock)sender).Stop = true;
157                    return;
158                }
159            }
160        }
161    }
162
163    //包含程序入口方法的类
164    public class AlarmDriver
165    {
166        public static void Main(string[] args)
167        {
168            //创建事件接收者对象实例
169            WakeMeUp waking = new WakeMeUp();
170
171            //创建事件发送者对象实例
172            AlarmClock clock = new AlarmClock();
173
174            //把事件处理方法绑定到发送者的事件上
175            clock.Alarm += new AlarmEventHandler(waking.AlarmRing);
176
177            clock.Start();
178        }
179    }
180}
181
182

运行结果：