回调处理

1、创建控制台程序

2、定义业务类和回调时传递的参数类型，如下：

class Work
    {
        public delegate void ValueChangedEventHandler(object sender, ValueChangedEventArgs e);
        public ValueChangedEventHandler ValueChanged;

        public void DoWork()
        {
            if (ValueChanged!=null)
            {
                ValueChanged(this, new ValueChangedEventArgs(DateTime.Now.Second));
            }
        }
    }

    public class ValueChangedEventArgs : EventArgs
    {
        public ValueChangedEventArgs(int value)
        {
            this.Value = value;
        }

        public int Value;
    }

3、在Main中使用业务类，并定义回调处理逻辑，如下：

 class Program
    {
        static void Main(string[] args)
        {
            Work work = new Work();

            //方式一
            work.ValueChanged += (o, e) =>{
                Console.WriteLine("方式一：" + Convert.ToString(e.Value));
            };

            //方式二
            work.ValueChanged += ChangedHandler;

            work.DoWork();
            System.Threading.Thread.Sleep(3 * 1000);
            work.DoWork();

            Console.Read();

        }

        private static void ChangedHandler(object sender, ValueChangedEventArgs e)
        {
            Console.WriteLine("方式二：" + Convert.ToString(e.Value));
        }
    }

4、运行，结果如下：

方式一：45
方式二：45
方式一：48
方式二：48