Java设计模式之单例模式

最新推荐文章于 2025-11-26 16:40:37 发布

原创最新推荐文章于 2025-11-26 16:40:37 发布 · 82 阅读

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#设计模式 #Java #Access

本文详细介绍了Singleton设计模式的目的和使用场景，通过一个简单的Java实现示例，展示了如何确保系统中一个类只有一个实例，并提供了对该实例的全局访问点。

[color=red]SINGLETON [/color] （Object Creational）

[color=red]Purpose[/color]
Ensures that only one instance of a class is allowed within a system.
[color=red]Use When[/color]
1 Exactly one instance of a class is required.
2 Controlled access to a single object is necessary.
[color=red]Example
[/color] Most languages provide some sort of system or environment
object that allows the language to interact with the native operating
system. Since the application is physically running on only one
operating system there is only ever a need for a single instance of
this system object. The singleton pattern would be implemented
by the language runtime to ensure that only a single copy of the
system object is created and to ensure only appropriate processes
are allowed access to it.


package javaPattern;

public class Singleton {

	private static Singleton singleton;
	private Singleton(){}//构造器必须私有
	public static Singleton getSingleton(){
		if(singleton == null){
			singleton =  new Singleton();
		}
		return singleton;
	}
	public static void main(String[] args) {
		Singleton s1 = Singleton.getSingleton();
		Singleton s2 = Singleton.getSingleton();
		System.out.println(s1 == s2);
	}
}