构造函数单例模式

 

单例模式只能实例化一次，重复实例化时属性不变

例：某某岗位只有一个人,无论如何重复调用，人员属性不变　

 public class privately   //单例模式
        {
            private static privately pri;  //定义

            public int age;

            public string name;

            public static privately Pri   //判断是否已经存在，如果否，实力化，若已被实例化,则禁止实例
            {
                get
                {
                    if (pri == null)
                    {
                        pri = new privately();
                    }
                    return pri;
                }

            }

            private privately()   //私有构造,不能在外界定义(因为用的是private私有属性，所以外面调不到,所以不能实力化)
            { }

            public void Me()
            {
                Console.WriteLine("My name is " + name +@",I'm "+age+" years old");
            }

            copy_file.privately man= copy_file.privately.Pri;  //调用私有函数

            man.age = 23; 
            man.name = "tt";
            man.Me();
            copy_file.privately man_1 = copy_file.privately.Pri; 
            man_1.Me();  //无论如何更改都无法改变私有函数的实例