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Spring Bean的生命周期函数

cnblogs 2024-07-22 08:09:01 阅读 87

🍓Bean的生命周期

  1. 📌Bean定义
  2. 📌Bean注册
  3. 📌Bean初始化
  4. 📌Bean销毁

🍓Bean注册

?>Bean定义时会调用BeanDefinitionRegistryPostProcessor的子类的两个实现方法<code>postProcessBeanDefinitionRegistry和postProcessBeanFactory。

  1. 📌postProcessBeanDefinitionRegistry，可以注册Bean（先调）

  2. 📌postProcessBeanFactory，可以获取到BeanFactory，BeanFactory能做的这个方法都能做（后调）

    点击查看代码

    import cn.com.xuhx.service.impl.UserServiceImpl;

    import org.springframework.beans.BeansException;

    import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;

    import org.springframework.beans.factory.support.BeanDefinitionRegistry;

    import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;

    import org.springframework.beans.factory.support.RootBeanDefinition;

    import org.springframework.stereotype.Component;

    /**

    * 作用：动态注册BeanDefinition

    * 调动时机：IOC加载注册BeanDefinition 的时候会调用

    */

    @Component

    public class MyBeanDefinitionRegistyPostProcessor implements BeanDefinitionRegistryPostProcessor {

    /**

    * 动态注册Bean

    * 先执行

    * @param beanDefinitionRegistry the bean definition registry used by the application context

    * @throws BeansException

    */

    @Override

    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry beanDefinitionRegistry) throws BeansException {

    RootBeanDefinition rootBeanDefinition = new RootBeanDefinition(UserServiceImpl.class);

    //手动注册UserServiceImpl的Bean

    beanDefinitionRegistry.registerBeanDefinition("userService", rootBeanDefinition);

    }

    /**

    * configurableListableBeanFactory Bean工厂，Bean工厂一切能做的，都能在这里做

    * 可以注册Bean

    * 可以修改BeanDefinition的定义 例如单例变多例

    * 可以通过Bean的名称获取Bean

    * 可以销毁Bean

    * 后执行

    * @param configurableListableBeanFactory the bean factory used by the application context

    * @throws BeansException

    */

    @Override

    public void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throws BeansException {

    }

    }

🍓Bean初始化

🍒🍒Aware接口

🍎🍎🍎BeanNameAware

?>通过实现BeanNameAware接口，重写setBeanName方法可以获得当前类的BeanName

点击查看代码

import org.springframework.beans.factory.BeanNameAware;

import org.springframework.stereotype.Service;

@Service

public class UserServiceImpl implements UserService, BeanNameAware {

/**

* UserServiceImpl的BeanName

*/

private String beanName;

/**

* 通过实现BeanNameAware重写setBeanName方法获取当前对象的BeanName

* @param name the name of the bean in the factory.

*/

@Override

public void setBeanName(String name) {

this.beanName = name;

}

public String getBeanName() {

return beanName;

}

}

🍎🍎🍎BeanFactoryAware

?>通过实现BeanFactoryAware接口，重写setBeanFactory方法可以获取BeanFactory，可以用于注册Bean、修改BeanDefinition定义、根据BeanName获取Bean，销毁Bean等。

点击查看代码

import org.springframework.beans.BeansException;

import org.springframework.beans.factory.BeanFactory;

import org.springframework.beans.factory.BeanFactoryAware;

import org.springframework.stereotype.Service;

@Service

public class UserServiceImpl implements UserService, BeanFactoryAware {

/**

* Bean工厂

*/

private BeanFactory beanFactory;

/**

* BeanFactoryAware重写的方法，可以获取BeanFactory

* @param beanFactory owning BeanFactory (never {@code null}).

* @throws BeansException

*/

@Override

public void setBeanFactory(BeanFactory beanFactory) throws BeansException {

this.beanFactory = beanFactory;

}

public BeanFactory getBeanFactory() {

return beanFactory;

}

}

🍎🍎🍎BeanClassLoaderAware

?>通过实现BeanClassLoaderAware接口，重写setBeanClassLoader方法可以获取类加载器，用于动态加载类

点击查看代码

import org.springframework.beans.factory.BeanClassLoaderAware;

import org.springframework.stereotype.Service;

@Service

public class UserServiceImpl implements UserService, BeanClassLoaderAware {

/**

* 类加载器

*/

private ClassLoader classLoader;

/**

* BeanClassLoaderAware重写的方法，可以获取类加载器

* @param classLoader the owning class loader

*/

@Override

public void setBeanClassLoader(ClassLoader classLoader) {

this.classLoader = classLoader;

}

public ClassLoader getClassLoader() {

return classLoader;

}

}

🍎🍎🍎EnvironmentAware

?>通过实现EnvironmentAware接口，重写setEnvironment方法可以获取Environment对象，用于读取配置文件

点击查看代码

import org.springframework.context.EnvironmentAware;

import org.springframework.core.env.Environment;

import org.springframework.stereotype.Service;

@Service

public class UserServiceImpl implements UserService, EnvironmentAware {

/**

* 环境管理对象

*/

private Environment env;

/**

* EnvironmentAware重写的方法，可以获取Environment

* @param environment

*/

@Override

public void setEnvironment(Environment environment) {

this.env = environment;

}

public Environment getEnv() {

return env;

}

}

🍎🍎🍎EmbeddedValueResolverAware

?>通过实现EmbeddedValueResolverAware接口，重写setEmbeddedValueResolver方法获取StringValueResolver对象，用于解析字符串

点击查看代码

import org.springframework.context.EmbeddedValueResolverAware;

import org.springframework.stereotype.Service;

import org.springframework.util.StringValueResolver;

@Service

public class UserServiceImpl implements UserService, EmbeddedValueResolverAware {

/**

* 字符串占位符解析对象

*/

private StringValueResolver resolver;

/**

* EmbeddedValueResolverAware重写的方法，可以获取StringValueResolver

* @param resolver

*/

@Override

public void setEmbeddedValueResolver(StringValueResolver resolver) {

this.resolver = resolver;

}

public StringValueResolver getResolver() {

return resolver;

}

@Override

public String getMessage() {

String message = "你好，${student.name}";

return resolver.resolveStringValue(message);

}

}

!>properties配置文件的中文需要转码(与编码格式无关)，否则会乱码，可以使用jdk8自带的程序native2ascii.exe编码

🍎🍎🍎ResourceLoaderAware

?>通过实现ResourceLoaderAware接口，重写setResourceLoader方法获取ResourceLoader对象，用于加载配置文件

点击查看代码

import org.springframework.context.ResourceLoaderAware;

import org.springframework.core.io.Resource;

import org.springframework.core.io.ResourceLoader;

import org.springframework.stereotype.Service;

import java.io.*;

@Service

public class UserServiceImpl implements UserService, ResourceLoaderAware {

/**

* resourceLoader对象

*/

private ResourceLoader resourceLoader;

@javax.annotation.Resource

private ResourceUtils resourceUtils;

/**

* ResourceLoaderAware重写的方法，可以获取resourceLoader

* @param resourceLoader

*/

@Override

public void setResourceLoader(ResourceLoader resourceLoader) {

this.resourceLoader = resourceLoader;

}

public String readFile() throws IOException {

Resource resource = resourceLoader.getResource("classpath:/abc");

return resourceUtils.getContent(resource);

}

}

🍎🍎🍎ApplicationEventPublisherAware

?>通过实现ApplicationEventPublisherAware接口，重写setApplicationEventPublisher方法获取ApplicationEventPublisher对象，用于订阅发布事件。

事件对象

import org.springframework.context.ApplicationEvent;

/**

* 用户事件

*/

public class UserEvent extends ApplicationEvent {

private String message;

private String topic;

public UserEvent(Object source, String message, String topic) {

super(source);

this.message = message;

this.topic = topic;

}

public String getMessage() {

return message;

}

public String getTopic() {

return topic;

}

}

事件监听器

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import org.springframework.context.event.EventListener;

import org.springframework.scheduling.annotation.Async;

import org.springframework.stereotype.Component;

/**

* 用户事件监听器

*/

@Component

public class UserEventListener {

/**

* 日志对象

*/

private final Logger logger = LoggerFactory.getLogger(this.getClass());

/**

* 监听器

* @param userEvent

*/

@EventListener(condition = "'heiBei'.equals(#userEvent.topic)")

@Async

public void receiveHeiBeiUser(UserEvent userEvent) {

logger.info("receive heiBei: " + userEvent.getTopic() + "：" + userEvent.getMessage());

}

/**

* 监听器

* @param userEvent

*/

@EventListener(condition = "'jiangSu'.equals(#userEvent.topic)")

@Async

public void receiveJiangSuUser(UserEvent userEvent) {

logger.info("receive JiangSu: " + userEvent.getTopic() + "：" + userEvent.getMessage());

}

}

发送消息

import org.springframework.context.ApplicationEventPublisher;

import org.springframework.context.ApplicationEventPublisherAware;

import org.springframework.stereotype.Service;

/**

* 消息发布

*/

@Service

public class UserServiceImpl implements UserService, ApplicationEventPublisherAware {

/**

* 消息发布对象

*/

private ApplicationEventPublisher applicationEventPublisher;

/**

* ApplicationEventPublisherAware重写的方法，可以获取applicationEventPublisher

* @param applicationEventPublisher

*/

@Override

public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {

this.applicationEventPublisher = applicationEventPublisher;

}

/**

* 发送消息

*/

public void publishEvent(String topic) {

UserEvent userTopic = new UserEvent(this, "Hello World!", topic);

applicationEventPublisher.publishEvent(userTopic);

}

}

🍎🍎🍎MessageSourceAware

?>通过实现MessageSourceAware接口，重写setMessageSource方法获取MessageSource对象，用于实现国际化功能

创建用户事件

import org.springframework.context.ApplicationEvent;

/**

* 用户事件

*/

public class UserEvent extends ApplicationEvent {

private String message;

private String topic;

public UserEvent(Object source, String message, String topic) {

super(source);

this.message = message;

this.topic = topic;

}

public String getMessage() {

return message;

}

public String getTopic() {

return topic;

}

}

用户事件监听器

import org.springframework.context.event.EventListener;

import org.springframework.scheduling.annotation.Async;

import org.springframework.stereotype.Component;

/**

* 用户事件监听器

*/

@Component

public class UserEventListener {

/**

* 日志对象

*/

private final Logger logger = LoggerFactory.getLogger(this.getClass());

/**

* 监听器（异步需要在启动器上加@EnableAsync）

* @param userEvent

*/

@EventListener(condition = "'heiBei'.equals(#userEvent.topic)")

@Async

public void receiveHeiBeiUser(UserEvent userEvent) {

logger.info("receive heiBei: " + userEvent.getTopic() + "：" + userEvent.getMessage());

}

/**

* 监听器

* @param userEvent

*/

@EventListener(condition = "'jiangSu'.equals(#userEvent.topic)")

@Async

public void receiveJiangSuUser(UserEvent userEvent) {

logger.info("receive JiangSu: " + userEvent.getTopic() + "：" + userEvent.getMessage());

}

}

发送消息

import org.springframework.context.MessageSource;

import org.springframework.context.MessageSourceAware;

import org.springframework.stereotype.Service;

import java.util.Locale;

/**

* 消息发布

*/

@Service

public class UserServiceImpl implements UserService, MessageSourceAware {

private MessageSource messageSource;

/**

* MessageSourceAware重写的方法，可以获取messageSource

* @param messageSource

*/

@Override

public void setMessageSource(MessageSource messageSource) {

this.messageSource = messageSource;

}

public String getMessage(String lanuageType) {

if ("US".equalsIgnoreCase(lanuageType)) {

return messageSource.getMessage("message", null, new Locale("en", "US"));

} else if ("CN".equalsIgnoreCase(lanuageType)) {

return messageSource.getMessage("message", null, new Locale("zh", "CN"));

}

return messageSource.getMessage("message", null, null);

}

}

创建Message配置文件

image

添加配置

<code>spring.messages.basename=i18n/Message

!>properties配置文件的中文需要转码(与编码格式无关)，否则会乱码，可以使用jdk8自带的程序native2ascii.exe编码

🍎🍎🍎ImportAware

?>通过实现ImportAware接口，重写setImportMetadata方法获取AnnotationMetadata对象，用于获取注解信息

点击查看代码

import org.springframework.context.annotation.ImportAware;

import org.springframework.core.type.AnnotationMetadata;

import org.springframework.stereotype.Service;

@Service

public class UserServiceImpl implements UserService, ImportAware {

/**

* 获取注解信息

*/

private AnnotationMetadata annotationMetadata;

/**

* ImportAware重写的方法，可以获取AnnotationMetadata

* @param importMetadata

*/

@Override

public void setImportMetadata(AnnotationMetadata importMetadata) {

annotationMetadata = importMetadata;

}

}

🍒🍒@PostConstruct

?>当Spring IOC Bean初始化时会调用@PostConstruct标注的方法

点击查看代码

import org.springframework.stereotype.Service;

import javax.annotation.PostConstruct;

@Service

public class UserServiceImpl implements UserService {

private Logger logger = LoggerFactory.getLogger(this.getClass());

/**

* 初始化

*/

@PostConstruct

public void init() {

logger.info("UserServiceImpl初始化");

}

}

🍓Bean生命周期的回调

🍒🍒BeanPostProcessor

?>Bean初始化前会调用BeanPostProcessor的postProcessBeforeInitialization方法，Bean初始化后会调用方法postProcessAfterInitialization

点击查看代码

import org.springframework.beans.BeansException;

import org.springframework.beans.factory.config.BeanPostProcessor;

import org.springframework.stereotype.Component;

@Component

public class MyBeanPostProcessor implements BeanPostProcessor {

private final Logger logger = LoggerFactory.getLogger(this.getClass());

/**

* Bean初始化前

* @param bean the new bean instance

* @param beanName the name of the bean

* @return

* @throws BeansException

*/

@Override

public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {

logger.info("postProcessBeforeInitialization Bean = {}, BeanName = {}", bean, beanName);

return BeanPostProcessor.super.postProcessBeforeInitialization(bean, beanName);

}

/**

* Bean初始化后

* @param bean the new bean instance

* @param beanName the name of the bean

* @return

* @throws BeansException

*/

@Override

public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {

logger.info("postProcessAfterInitialization Bean = {}, BeanName = {}", bean, beanName);

return BeanPostProcessor.super.postProcessAfterInitialization(bean, beanName);

}

}

🍒🍒InitializingBean

?>Bean初始化会调用InitializingBean的实现方法afterPropertiesSet，作用相当于@PostConstruct

点击查看代码

import org.springframework.beans.factory.InitializingBean;

import org.springframework.stereotype.Service;

@Service

public class UserServiceImpl implements UserService, InitializingBean {

private Logger logger = LoggerFactory.getLogger(this.getClass());

@Override

public void afterPropertiesSet() throws Exception {

logger.info("UserServiceImpl初始化");

}

}

🍒🍒init-method

?>Bean初始化会调用init-method指定的方法，作用相当于InitializingBean.afterPropertiesSet和@PostConstruct

点击查看代码

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

@Configuration

public class BeanConfiguration {

@Bean(name = "userService", initMethod = "init")

public UserService getUserService() {

return new UserServiceImpl();

}

}

🍒🍒DisposableBean

?>Bean销毁会调用DisposableBean的实现方法destroy

点击查看代码

import org.springframework.beans.factory.DisposableBean;

import org.springframework.stereotype.Service;

@Service

public class UserServiceImpl implements UserService, DisposableBean {

private Logger logger = LoggerFactory.getLogger(this.getClass());

@Override

public void destroy() throws Exception {

logger.info("UserServiceImpl被销毁了");

}

}

🍒🍒destroy-method

?>Bean销毁会调用destroy-method指定的方法，作用相当于DisposableBean.destroy

点击查看代码

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

@Configuration

public class BeanConfiguration {

@Bean(name = "userService", destroyMethod = "destroy")

public UserService getUserService() {

return new UserServiceImpl();

}

}

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