Spring中的singleton和prototype的实现

package com.demo.dao;

public class UserDao {

  public UserDao(){
    System.out.println("UserDao 无参构造函数被调用");
  }
  //获取用户名
  public String getUserName(){
    //模拟dao层
    return "Alan_beijing";
  }
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

  <bean class="com.demo.dao.UserDao" id="userDao" scope="singleton"/>
</beans>

public class MyTest {

  @Test
  public void test(){
    //定义容器并初始化
    ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");

    //定义第一个对象
    UserDao userDao = applicationContext.getBean(UserDao.class);
    System.out.println(userDao.getUserName());

    //定义第二个对象
    UserDao userDao2 = (UserDao) applicationContext.getBean("userDao");
    System.out.println(userDao2.getUserName());
    //比较两个对象实例是否是同一个对象实例
    System.out.println("第一个实例："+userDao+"\n"+"第二个实例："+userDao2);
  }
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

  <bean class="com.demo.dao.UserDao" id="userDao" scope="prototype"/>
</beans>