【转载】单例模式的4种实现⽅式using System;
using System.Collections.Generic;
using System.Text;
namespace SingletonDemo
{
///<summary>
/// 1、普通单例
///</summary>
public class SingletonA
{
private static SingletonA _instance = null;
private SingletonA() { }
public static SingletonA CreateInstance()
{
if (_instance == null)
{
_instance = new SingletonA();
}
return _instance;
}
}
///<summary>
/
// 2、线程安全单例
///</summary>
public class SingletonB
{
private volatile static SingletonB _instance = null;
private static readonly object lockHelper = new object();
private SingletonB() { }
public static SingletonB CreateInstance()
{
if (_instance == null)
{
lock (lockHelper)
{
if (_instance == null)
_instance = new SingletonB();
}
}
return _instance;
}
}
///<summary>
/// 3、使⽤特性的⽀持多线程的单件模式代码
/
//</summary>
public sealed class SingletonC
{
private SingletonC() { }
public static readonly SingletonC Instance = new SingletonC();
}
///<summary>
/// 4、使⽤ C# 2.0 泛型来完成单例模式的重⽤
///</summary>
///<typeparam name="T"></typeparam>
public class SingletonProvider<T> where T : new()
{
SingletonProvider() { }
public static T Instance
{
get { return SingletonCreator.instance; }
}
class SingletonCreator
{
static SingletonCreator() { }
internal static readonly T instance = new T();
}
}
///<summary>
/// 4、业务类demo
///</summary>
public class TestClass
{
private string _createdTimestamp;
public TestClass()
{单例模式的几种实现方式
_createdTimestamp = DateTime.Now.ToString(); }
public void Write()
{
Console.WriteLine(_createdTimestamp);
}
}
///<summary>
/// 4、范型单例⽰例
///</summary>
public class demo
{
private void dosomething()
{
SingletonProvider<TestClass>.Instance.Write(); }
}
}

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