SmartInitializingSingleton接口具有什么功能呢?

SmartInitializingSingleton接口简介

 
SmartInitializingSingleton接口的作用
    当IOC容器加载完 所有的单例Bean后
	可运行接口中的方法 

SmartInitializingSingleton的定义

public interface SmartInitializingSingleton {
    void afterSingletonsInstantiated();
}
 
for (String beanName : beanNames) {
    Object singletonInstance = getSingleton(beanName);
    //如果实现SmartInitializingSingleton接口，则执行其afterSingletonsInstantiated方法
    if (singletonInstance instanceof SmartInitializingSingleton) {
        SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance;
        if (System.getSecurityManager() != null) {
            AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
                smartSingleton.afterSingletonsInstantiated();
                return null;
            }, getAccessControlContext());
        }
        else {
            smartSingleton.afterSingletonsInstantiated();
        }
    }
}

SmartInitializingSingleton的使用

package com.jd.startUpCompletedRunMethod;


import org.springframework.beans.factory.SmartInitializingSingleton;

public class RunMethod implements SmartInitializingSingleton {

    @Override
    public void afterSingletonsInstantiated() {
        System.out.println("Spring加载完毕====>  class:"+this.getClass().toString());
    }
}


将这个 bean交给 Spring管理
Spring初始化完毕后，则会运行  afterSingletonsInstantiated 中的内容