文章目录

• 1. Bean生命周期
• • 1.1 @Bean注解指定初始化和销毁方法
  • 1.2 实现 InitializingBean、DisposableBean接口
  • 1.3 使用注解@PostConstruct 、@PreDestory
  • 1.4 实现 BeanPostProcessor 接口

1. Bean生命周期

1.1 @Bean注解指定初始化和销毁方法

// 使用方法: 利用@Bean的 initMethod 和 destroyMethod 属性指定相应方法的名称
@Bean(initMethod = "initMethod", destroyMethod = "destroyMethod")

initMethod() 初始化之后
destroyMethod() 销毁之前

public class User {

    public User() {
        System.out.println("user构造器...");
    }
 
    private String name;
    private Integer age;

    public void initMethod() {
        System.out.println("我是initMethod...");
    }

    public void destroyMethod() {
        System.out.println("我是destroyMethod...");
    }
}

测试

@Configuration
public class MyConfig {

    @Bean(initMethod = "initMethod", destroyMethod = "destroyMethod")
    public User user() {
        User user = new User();
        return user;
    }
}

    @Test
    public void test() {
        AnnotationConfigApplicationContext annotationConfigApplicationContext = new AnnotationConfigApplicationContext(MyConfig.class);
        annotationConfigApplicationContext.getBean("user");
        annotationConfigApplicationContext.close();
    }

1.2 实现 InitializingBean、DisposableBean接口

InitializingBean 属性设置之后
DisposableBean 销毁之前

public class User implements InitializingBean, DisposableBean {

    public User() {
        System.out.println("user构造器...");
    }

    private String name;
    private Integer age;

    public void initMethod() {
        System.out.println("我是initMethod...");
    }

    public void destroyMethod() {
        System.out.println("我是destroyMethod...");
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("我是afterPropertiesSet...");
    }

    @Override
    public void destroy() throws Exception {
        System.out.println("我是destroy...");
    }
}

测试

    @Test
    public void test() {
        AnnotationConfigApplicationContext annotationConfigApplicationContext = new AnnotationConfigApplicationContext(MyConfig.class);
        annotationConfigApplicationContext.getBean("user");
        annotationConfigApplicationContext.close();
    }

1.3 使用注解@PostConstruct 、@PreDestory

@PostConstruct 初始化之后
@PreDestory 销毁之前

public class User implements InitializingBean, DisposableBean {

    public User() {
        System.out.println("user构造器...");
    }

    private String name;
    private Integer age;

    public void initMethod() {
        System.out.println("我是initMethod...");
    }

    public void destroyMethod() {
        System.out.println("我是destroyMethod...");
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("我是afterPropertiesSet...");
    }

    @Override
    public void destroy() throws Exception {
        System.out.println("我是destroy...");
    }

    @PostConstruct
    public void postConstruct() {
        System.out.println("我是PostConstruct...");
    }

    @PreDestroy
    public void preDestroy() {
        System.out.println("我是preDestroy...");
    }
}

测试

    @Test
    public void test() {
        AnnotationConfigApplicationContext annotationConfigApplicationContext = new AnnotationConfigApplicationContext(MyConfig.class);
        annotationConfigApplicationContext.getBean("user");
        annotationConfigApplicationContext.close();
    }

1.4 实现 BeanPostProcessor 接口

创建一个类实现 BeanPostProcessor
postProcessBeforeInitialization() 初始化之前，优先于上面三种
postProcessAfterInitialization() 初始化之后

public class MyBeanPostProcessor implements BeanPostProcessor {

    /**
     * 初始化之前调用
     */
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("我是postProcessBefore... beanName=" + beanName);
        return bean;
    }

    /**
     * 初始化之后调用
     */
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("我是postProcessAfter... beanName=" + beanName);
        return bean;
    }
}

通过@Bean 注册到容器中

@Configuration
public class MyConfig {

    @Bean(initMethod = "initMethod", destroyMethod = "destroyMethod")
    public User user() {
        User user = new User();
        return user;
    }

    @Bean
    public MyBeanPostProcessor myBeanPostProcessor() {
        return new MyBeanPostProcessor();
    }
}

测试

    @Test
    public void test() {
        AnnotationConfigApplicationContext annotationConfigApplicationContext = new AnnotationConfigApplicationContext(MyConfig.class);
        annotationConfigApplicationContext.getBean("user");
        annotationConfigApplicationContext.close();
    }