Sigleton模式简单实例

///<summary>
/// Sigleton模式简单实例
///</summary>
class Program
    {
staticvoid Main(string[] args)
        {
string _title;
//调用者不可以通过new的形式得到Singleton的实例
            LogWriter log = LogWriter.GetInstance();
            log.ddd();
//调用LogWriter中的静态字段（外部类的类类型，只能通过类型访问而不能通过实例访问）
            _title = LogWriter._boss.Title;
            LogWriter._boss.SayHi();
            Console.WriteLine(_title);
            Console.ReadLine();
        }
#region LogWriter描述
publicclass LogWriter
        {
//声明一个静态变量，类型为类本身
privatestatic LogWriter _instance =null;
//声明一个静态变量，类型为一外部类
publicstatic Boss _boss =new Boss();//注意此处必须初始化，否则，调用会报错:{未将引用添加到实例}
//将类的构造函数私有化，使得这个类不可以被外界创建
private  LogWriter()
            {
            }
//提供静态的方法创建类的实例
publicstatic LogWriter GetInstance()
            {
if(_instance ==null)
                {
                    _instance =new LogWriter();
                }
return _instance;
            }
publicvoid ddd()
            {
                Console.WriteLine("hi!");
            }
        }
#endregion

#region Boss描述
publicclass Boss
        {
privatestring _Title;

publicstring Title
            {
get { return _Title; }
set { _Title = value; }
            }

public Boss()
            {
this._Title ="Lucky";
            }
publicvoid SayHi()
            {
                Console.WriteLine("Hello,World!");
            }
        }
#endregion
    }