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[Spring]-组件的生命周期

news 来源：原创 2025/5/15 6:31:54

组件生命周期

认识组件的声明周期

实验1

通过@Bean指定组件的生命周期

package com.guigu.spring.ioc.bean;@Data
public class User {private String username;private String password;private Car car;@Autowiredpublic void setCar(Car car) {System.out.println("自动注入: 属性值" + car);this.car = car;}public User() {System.out.println("User 构造器...");}/*** 组件初始化*/public void initUser() {System.out.println("User组件初始化");}/*** 组件销毁*/public void destoryUser() {System.out.println("User组件销毁");}
}

package com.guigu.spring.ioc.config;@Configuration
public class UserConfig {@Bean(initMethod = "initUser", destroyMethod = "destoryUser")public User user() {return new User();}
}

package com.guigu.spring.ioc;/*** 主入口文件*/
@SpringBootApplication
public class Spring01IocApplication {/*** 组件的声明周期*/public static void main(String[] args) {ConfigurableApplicationContext ioc = SpringApplication.run(Spring01IocApplication.class, args);}}

实验2

了解 InitializingBean接口和 DisposableBean接口的调用时机

package com.guigu.spring.ioc.bean;@Data
public class User implements InitializingBean, DisposableBean {private String username;private String password;private Car car;@Autowiredpublic void setCar(Car car) {System.out.println("setter自动注入: 属性值" + car);this.car = car;}public User() {System.out.println("User 构造器...");}/*** 组件初始化*/public void initUser() {System.out.println("User组件初始化");}/*** 组件销毁*/public void destoryUser() {System.out.println("User组件销毁");}/*** 属性设置之后调用: set赋值完成了* @throws Exception*/@Overridepublic void afterPropertiesSet() throws Exception {System.out.println("[InitializingBean]接口调用afterPropertiesSet方法");}@Overridepublic void destroy() throws Exception {System.out.println("[DisposableBean]接口调用destroy方法");}
}

实验3

了解 @PostConstruct 和 @PreDestroy 的执行时机

package com.guigu.spring.ioc.bean;@Data
public class User implements InitializingBean, DisposableBean {private String username;private String password;private Car car;/*** 构造器后置处理钩子* 构造器之后执行*/@PostConstructpublic void postConstruct() {System.out.println("@PostConstruct....");}/*** 销毁预处理钩子*/@PreDestroypublic void preDestroy() {System.out.println("@PreDestroy....");}
}

实验4

理解后置处理器机制: 前面的周期都是本质都是通知, 处理机制本质是拦截, 可以直接修改bean

package com.guigu.spring.ioc.processor;@Component // 拦截所有Bean的后置处理器
public class MyTestBeanPostProcessor implements BeanPostProcessor {@Overridepublic Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {System.out.println("[postProcessBeforeInitialization]: " + beanName);if(bean instanceof User hello) {hello.setUsername("张三测试");System.out.println("User: " + bean);}return bean;}@Overridepublic Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {System.out.println("[postProcessAfterInitialization]: " + beanName);return bean;}
}

单元测试

使用单元测试测试容器

@SpringBootTest注解用来开启测试,
是测试那个主程序类呢? 根据包进行匹配,
所以单元测试类所在的包要和主程序所在的包保持一致

注入组件并查看

package com.guigu.spring.ioc;@SpringBootTest // 测试SpringBoot功能, 测试容器
class Spring01IocApplicationTests {@AutowiredCar car;@Testvoid contextLoads() {System.out.println(car);}}

查看容器的创建