spring-自定义注解

最新推荐文章于 2024-11-28 14:49:50 发布

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最新推荐文章于 2024-11-28 14:49:50 发布

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分类专栏： spring教程

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#spring注解

理解spring bean 生命周期

实例化：spring对bean进行实例化
填充属性：spring将值和Bean的引用注入到Bean对应属性
调用BeanNameAware的setBeanName()：如果Bean实现了该接口，Spring将Bean的ID传递给setBeanName()
调用BeanFactoryAware的setBeanFactory()：如果Bean实现了该接口，Spring将BeanFactory容器实例传入
调用ApplicationContextAware的setApplicationContext()：如果Bean实现了该接口，Spring将bean所在的上下文引用传入
调用BeanPostProcessor的预初始化方法：Spring调用他们的 postProcessBeforeInitialization()
调用InitializingBean的afterPropertiesSet():Spring调用他们的afterPropertiesSet().类似的bean使用init-method，该方法被调用
调用自定义的初始化方法
调用BeanPostProcessor的初始化方法：Spring调用他们的 postProcessAfterInitialization()
bean使用
容器关闭
调用DisposableBean的destroy()
调用自定义的销毁方法

自定义注解接口

spring 通过此类扫描：org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider。
默认并将带@Component扫描，通过方法registerDefaultFilters(),并注入到spring容器中。

示例：

@Target({ ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface MyComponent {
    String value() default "";
}

@Configuration
@ComponentScan(includeFilters = {@ComponentScan.Filter(type = FilterType.ANNOTATION,value = ComponentAnnotationTest.MyComponent.class)})

注解处理类

    @Component
    public class BoyAnnotationBeanPostProcessor implements BeanPostProcessor {
        @Override
        public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
            return bean;
        }

        @Override
        public Object postProcessAfterInitialization(Object o, String s) throws BeansException {
            return o;
        }
    }

添加BeanScannerConfigurer

继承ApplicationContextAware接口，Spring会读取ApplicationContextAware类型的的JavaBean，并调用setApplicationContext(ApplicationContext applicationContext)传入Spring的applicationContext。
继承BeanFactoryPostProcessor接口，Spring会在BeanFactory的相关处理完成后调用postProcessBeanFactory方法，进行定制的功能

package com.nbd.ocp.study.springboot.annotation;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;


@Component
public class BeanScannerConfigurer implements BeanFactoryPostProcessor, ApplicationContextAware {
    private ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throws BeansException {

    }
}

参考