事件用法实例

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

namespace Event
{
    /// <summary>
    /// 自定义一个事件参数类型
    /// </summary>
    public class ConsoleEventArgs:EventArgs
    {
        private String _message;
        /// <summary>
        /// 无参构造函数
        /// </summary>
        public ConsoleEventArgs():base()
        {
            _message = null;
        }
        /// <summary>
        /// 带参构造函数
        /// </summary>
        /// <param name="message">信息</param>
        public ConsoleEventArgs(string message):base()
        {
            _message = message;
        }
        /// <summary>
        /// 属性，只读
        /// </summary>
        public string Message
        {
            get { return _message; }
        }
    }

    /// <summary>
    /// 管理控制台，在输出前发送输出事件
    /// </summary>
    public class ConsoleManage
    {
        //定义控制台事件成员对象
        public event EventHandler<ConsoleEventArgs> ConsoleEvent;

        /// <summary>
        /// 控制台输出
        /// </summary>
        /// <param name="message">参数</param>
        public void ConsoleOutput(string message)
        {
            ConsoleEventArgs args = new ConsoleEventArgs(message);
            SendConsoleEvent(args);
            Console.WriteLine(message);

        }

        /// <summary>
        /// 负责发送事件
        /// </summary>
        /// <param name="args"></param>
        protected virtual void SendConsoleEvent(ConsoleEventArgs args)
        {
            // 定义一个临时引用变量，这样可以确保多线程访问时不会发生问题
            EventHandler<ConsoleEventArgs> temp = ConsoleEvent;
            if (temp!=null)
            {
                temp(this, args);
            }
        }
    }

    /// <summary>
    /// 日志类，订阅控制台输出事件
    /// </summary>
    public class Log
    {
        //日志文件
        private const string LogFile = "C:\\Test\\Log.txt";

        public Log(ConsoleManage cm)
        {
            //订阅输出事件
            cm.ConsoleEvent += WriteLog;
        }

        private void WriteLog(object send, EventArgs arg)
        {
            if (!File.Exists(LogFile))
            {
                using(FileStream fs=File.Create(LogFile)){}
            }
            FileInfo info = new FileInfo(LogFile);
            using(StreamWriter sw=info.AppendText())
            {
                sw.WriteLine(DateTime.Now.ToString() + " | " + send.ToString() + " | " + ((ConsoleEventArgs)arg).Message);
            }
        }
    }

    class ConsoleEvent
    {
        static void Main(string[] args)
        {
            ConsoleManage cm = new ConsoleManage();
            Log log = new Log(cm);
            cm.ConsoleOutput("测试控制台输出事件");
            cm.ConsoleOutput("测试控制台输出事件");
            cm.ConsoleOutput("测试控制台输出事件");
            Console.Read();
        }
    }

}