public sealed class SingletonFirst
{
private SingletonFirst() { }
private static SingletonFirst _Instance = null;
public static SingletonFirst Instance
{
get
{
if (_Instance == null)
{
_Instance = new SingletonFirst();
Console.WriteLine(nameof(SingletonFirst) + "实例化了");
}
return _Instance;
}
}
}
public sealed class SingletonSecond
{
private SingletonSecond() { }
private static SingletonSecond _Instance = null;
private static readonly object _Locker = new object();
public static SingletonSecond Instance
{
get
{
//这样可以避免并发多次实例化，
//但是会影响性能，每一次进来判断都是排队，性能缺失很大
CoreService.RunLock(_Locker, () =>
{
if (_Instance == null)
{
_Instance = new SingletonSecond();
Console.WriteLine(nameof(SingletonSecond) + "实例化了");
}
});
return _Instance;
}
}
}
public sealed class SingletonThird
{
private SingletonThird() { }
private static SingletonThird _Instance = null;
private static readonly object _Locker = new object();
public static SingletonThird Instance
{
get
{
//通过两次判断，即不会特别影响性能，还可以达到单例的效果
//可以多线程进行判断操作，但是如果未实例化，再次进去实例化的时候，就要进行排队判断了
if (_Instance == null)
{
CoreService.RunLock(_Locker, () =>
{
if (_Instance == null)
{
_Instance = new SingletonThird();
Console.WriteLine(nameof(SingletonThird) + "实例化了");
}
});
}
return _Instance;
}
}
}
public sealed class SingletonStatic
{
private SingletonStatic() { }
private static SingletonStatic _Instance = null;
//利用静态构造函数的特性：在第一次使用该类时会有且仅有调用一次该静态构造函数，这样可以达到单例的效果
static SingletonStatic()
{
_Instance = new SingletonStatic();
Console.WriteLine(nameof(SingletonStatic) + "实例化了");
}
public static SingletonStatic Instance
{
get
{
return _Instance;
}
}
}
class Program
{
static void Main(string[] args)
{
try
{
//TestFirst();
//TestSecond();
//TestThird();
TestStatic();
}
catch (Exception e)
{
Console.WriteLine("发生异常：" + e.Message);
}
Console.WriteLine("End");
Console.ReadKey();
}
private static void TestFirst()
{
for (int i = 1; i <= 100; i++)
{
Task.Run(() =>
{
var instance = SingletonFirst.Instance;
});
}
}
private static void TestSecond()
{
for (int i = 1; i <= 100; i++)
{
Task.Run(() =>
{
var instance = SingletonSecond.Instance;
});
}
}
private static void TestThird()
{
for (int i = 1; i <= 100; i++)
{
Task.Run(() =>
{
var instance = SingletonThird.Instance;
});
}
}
private static void TestStatic()
{
for (int i = 1; i <= 100; i++)
{
Task.Run(() =>
{
var instance = SingletonStatic.Instance;
});
}
}
}
