Spring will invoke specific constructor no matter this constructor is public or private

I have confirm this conclusion via debugging my own code.

Spring will invoke specific constructor no matter this constructor is public or private

This is my demo:

package com.frank.zk;

/**
*
* @author liushaomingdev@163.com
*
*/
public class ZooKeeperManager extends ZookeeperClient implements Watcher {
private static ZooKeeperManager INSTANCE;
private ZooKeeperManager() {
INSTANCE = this;
}
public static ZooKeeperManager getInstance() {
return INSTANCE;
}
}

this is configuration file--applicationContext.xml

<?xml version="1.0" encoding="utf-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:util="http://www.springframework.org/schema/util" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.1.xsd"> <bean id="zookeeper" class="com.frank.zk.ZooKeeperManager" lazy-init="false" />
</beans>

Program execute to this break point finally.

private ZooKeeperManager() {
INSTANCE = this;
}

So,  below conclusion is confirmed:
Spring will invoke specific constructor no matter this constructor is public or private

This program use Spring to initialize singleton creating bean. It also uses Factory pattern to instantiate object.

Demo code

// bean 'ZooKeeperManager' is registered as singleton bean in Spring Container after this line code.
ApplicationContext appContext = new ClassPathXmlApplicationContext("appContext.xml");

ZooKeeperManager manager = ZooKeeperManager.getInstance();