单例模式演示-1-39-07

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;

namespace _01单例模式演示
{
    class Program
    {
        static void Main(string[] args)
        {

            //for (int i = 0; i < 100; i++)
            //{
            //    Person p = new Person();

            //    Person p1 = new Person();
            //}

            //Person p = new Person(

            //for (int i = 0; i < 1000; i++)
            //{
            //    Person p = Person.GetInstance();
            //}

            for (int i = 0; i < 1000; i++)
            {

                Thread t = new Thread(new ThreadStart(() =>
                {
                    //Person p = Person.GetInstance();
                    //Singleton p = Singleton.GetInstance();

                    Singleton2 s2 = Singleton2.GetInstance();
                }));
                t.Start();
            }
            Console.WriteLine("ok");
            Console.Read();





        }
    }


    //利用静态字段，在第一次使用类的时候只初始化一次的特性。
    public class Singleton2
    {
        private Singleton2()
        {
            Console.WriteLine(".");
        }
        private static readonly Singleton2 _instance = new Singleton2();

        public static Singleton2 GetInstance()
        {
            return _instance;
        }
    }







    public class Singleton
    {
        private Singleton()
        {
            Console.WriteLine(".");
        }

        private static Singleton _instance;

        private static readonly object syn = new object();

        public static Singleton GetInstance()
        {
            //lock (syn)
            //{
            //    if (_instance == null)
            //    {
            //        _instance = new Singleton();
            //    }
            //    return _instance;
            //}
            if (_instance == null)
            {
                lock (syn)
                {
                    if (_instance == null)
                    {
                        _instance = new Singleton();
                    }

                }
            }
            return _instance;

        }
    }




    public class Person
    {

        //把类的构造函数的访问修饰符改为private
        private Person()
        {
            Console.WriteLine(".");
        }

        private static Person _instance = null;

        public static Person GetInstance()
        {
            if (_instance == null)
            {
                _instance = new Person();
            }
            return _instance;
        }


        public string Name { get; set; }
        public string Email { get; set; }
        public int Age { get; set; }
    }
}