求ASP.NET答案

Question

用C#写出singleton（单例）模式的例子?
能否给出个实例来啊，对这个不了解....会的帮下忙吧！！！求教！！！

Answer 1

public class singleton
{
   static singleton _instance;
   private singleton()
   {}
   public singleton instance{
     if(_instance == null )
       _instance = new singleton;
     return _instance;
   }
}

Answer 2

public singleton instance{ ===>
public static singleton instance{ 

Answer 3

下面的代码会更好点，线程安全的
public class singleton 
{ 
  static singleton _instance; 
  
  static singleton()
  {
     _instance = new singleton; 
  }
  
  private singleton() 
  {} 
  public singleton instance{ 
      return _instance; 
  } 
}

Answer 4

class Singleton
{
    public static readonly Singleton instance = new Singleton();
    private Singleton(){ }
}

Answer 5

http://www.cnblogs.com/JasonChou/archive/2009/03/18/1415661.html

Answer 6

public class Singleton<T>
    {
        private static T _instance;        public Singleton()
        {
        }        public static T Instance
        {
            get
            {
                if (_instance == null)
                {
                    _instance = (T)System.Activator.CreateInstance(typeof(T));
                }
                return _instance;
            }
        }
    }
    public class Foo
    {
        private int count = 0;        public int Count
        {
            get
            {
                count++;
                return count;
            }
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(Singleton<Foo>.Instance.Count);
            Console.WriteLine(Singleton<Foo>.Instance.Count);
            Console.WriteLine(Singleton<Foo>.Instance.Count);            Console.ReadLine();
        }
    }