.net 单例模式

 1 public class Student
 2 {
 3        private static Student stu;
 4        private static object _obj= new object();
 5        private Student(){};
 6        public static Instance()
 7        {
 8           if(stu==null)
 9           {
10               lock(_obj)   //锁定代码区
11               {
12                   if(stu==null)
13                    {
14                         stu = new Student();
15                     }
16                }
17           }
18          return stu;
19         }      
20 }
21 
22 public class Test
23 {
24      void Main(string[] args)
25      {
26            Student stu1 = Student.Instance();
27            Student stu2 = Student.Instance();
28            if (stu1.Equals(stu2))
29            {
30                Console.WriteLine("是同一个对象的引用");
31            }
32            else
33            {
34                Console.WriteLine("是两个不同的对象的引用"); 
35            }  
36     }
37 }