面试题复习-常用设计模式-单例设计模式

Posted 2022-06-06 caizhiqin

饿汉式：

package com.ajax.pattern.singleton;

import lombok.AccessLevel;
import lombok.AllArgsConstructor;

@AllArgsConstructor(access = AccessLevel.PRIVATE)
public class Singleton 
    private static Singleton singleton = new Singleton();

    public static Singleton getInstance() 
        return singleton;
    

懒汉式：

package com.ajax.pattern.singleton;

import lombok.AccessLevel;
import lombok.AllArgsConstructor;

@AllArgsConstructor(access = AccessLevel.PRIVATE)
public class SingletonEx 
    private static SingletonEx instance = null;

    public static SingletonEx getInstance() 
        if (instance == null) 
            synchronized (SingletonEx.class) 
                if (instance == null) 
                    instance = new SingletonEx();
                
            
        
        return instance;
    

枚举：——