VIPJAVA/spring-demo/src/main/java/com/sf/ioc/singleton/Singleton4.java

package com.sf.ioc.singleton;

/**
 * 单例最好的实现方式
 * 枚举
 */
public enum Singleton4 {
    INSTANCE;
    // public static final Singleton4 INSTANCE = new Singleton4();
}