因为Spring框架默认的是单例模式，并且是“饿汉式”的，我们可以通过注解@Lazy来配置为“懒汉式”的！
如果配置当前类中的生命周期处理，先要定义俩个方法，初始化方法和销毁方法，然后再在初始化方法前面添加@PostConstruct注解，在销毁方法前面添加@PreDestroy注解。(这两注解跟Spring无关，jre版本低的话是无法识别这两注解的！)
package cn.tedu.spring; import javax.annotation.PostConstruct; import javax.annotation.PreDestroy; import org.springframework.stereotype.Repository; @Repository public class User { public User() { System.out.println("User.User()"); } @PostConstruct public void init() { System.out.println("User.init()"); } @PreDestroy public void destroy() { System.out.println("User.destroy()"); } } package cn.tedu.spring; import org.springframework.context.annotation.ComponentScan; @ComponentScan("cn.tedu.spring") public class SpringConfig { } package cn.tedu.spring; import org.springframework.context.annotation.AnnotationConfigApplicationContext; public class Demo { public static void main(String[] args) { //加载配置，获取Spring容器 System.out.println("开始获取Spring容器.."); AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(SpringConfig.class); System.out.println("获取容器成功！"); //从Spring中获取对象 System.out.println("准备获取对象..."); User user1 = ac.getBean("user",User.class); User user2 = ac.getBean("user",User.class); User user3 = ac.getBean("user",User.class); System.out.println("对象获取成功！"); System.out.println("开始测试，，，"); System.out.println(user1); System.out.println(user2); System.out.println(user3); System.out.println("测试成功！"); System.out.println("将要关闭..."); ac.close(); System.out.println("关闭成功！"); } }