[Spring]-组件的生命周期

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;

    @Autowired
    public 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;

    @Autowired
    public 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
     */
    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("[InitializingBean]接口调用afterPropertiesSet方法");
    }

    @Override
    public 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
     */
    @PostConstruct
    public void postConstruct() {
        System.out.println("@PostConstruct....");
    }

    /**
     * 销毁预处理钩子
     */
    @PreDestroy
    public 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 {
    @Override
    public 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;
    }

    @Override
    public 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 {

    @Autowired
    Car car;

    @Test
    void contextLoads() {
        System.out.println(car);
    }

}

查看容器的创建

查看单元测试方法的结果