深度解析Spring Bean生命周期的各個(gè)階段

更新時(shí)間：2025年09月23日 09:30:07 作者：猿究院-陸昱澤

本文將詳細(xì)梳理Spring Bean生命周期的各個(gè)階段,并通過代碼示例展示每個(gè)關(guān)鍵節(jié)點(diǎn),本文結(jié)合實(shí)例代碼給大家介紹的非常詳細(xì),對大家的學(xué)習(xí)或工作具有一定的參考借鑒價(jià)值,需要的朋友參考下吧

概述

Spring Bean的生命周期是Spring框架的核心概念之一，理解Bean從創(chuàng)建到銷毀的整個(gè)過程對于開發(fā)高質(zhì)量的Spring應(yīng)用程序至關(guān)重要。本文將詳細(xì)梳理Spring Bean生命周期的各個(gè)階段，并通過代碼示例展示每個(gè)關(guān)鍵節(jié)點(diǎn)。

Spring Bean生命周期階段

1. 實(shí)例化階段

Spring容器通過構(gòu)造函數(shù)或工廠方法創(chuàng)建Bean實(shí)例

public class ExampleBean {
    public ExampleBean() {
        System.out.println("1. Bean實(shí)例化 - 構(gòu)造函數(shù)執(zhí)行");
    }
}

2. 屬性賦值階段

Spring容器注入Bean的屬性和依賴

public class ExampleBean {
    private String name;
    private AnotherBean anotherBean;
    // Setter方法用于屬性注入
    public void setName(String name) {
        System.out.println("2. 屬性注入 - name: " + name);
        this.name = name;
    }
    public void setAnotherBean(AnotherBean anotherBean) {
        System.out.println("2. 依賴注入 - anotherBean");
        this.anotherBean = anotherBean;
    }
}

3. Aware接口回調(diào)階段

Bean實(shí)現(xiàn)Aware接口獲取容器資源

public class ExampleBean implements BeanNameAware, BeanFactoryAware, ApplicationContextAware {
    @Override
    public void setBeanName(String name) {
        System.out.println("3. BeanNameAware - Bean名稱: " + name);
    }
    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        System.out.println("3. BeanFactoryAware - BeanFactory注入");
    }
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        System.out.println("3. ApplicationContextAware - ApplicationContext注入");
    }
}

4. BeanPostProcessor前置處理

BeanPostProcessor的postProcessBeforeInitialization方法

@Component
public class CustomBeanPostProcessor implements BeanPostProcessor {
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        if (bean instanceof ExampleBean) {
            System.out.println("4. BeanPostProcessor前置處理 - " + beanName);
        }
        return bean;
    }
}

5. 初始化階段

@PostConstruct注解方法

public class ExampleBean {
    @PostConstruct
    public void postConstruct() {
        System.out.println("5.1 @PostConstruct方法執(zhí)行");
    }
}

InitializingBean接口

public class ExampleBean implements InitializingBean {
    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("5.2 InitializingBean.afterPropertiesSet()執(zhí)行");
    }
}

自定義init方法

public class ExampleBean {
    public void customInit() {
        System.out.println("5.3 自定義init方法執(zhí)行");
    }
}
// 配置類中指定init方法
@Configuration
public class AppConfig {
    @Bean(initMethod = "customInit")
    public ExampleBean exampleBean() {
        return new ExampleBean();
    }
}

6. BeanPostProcessor后置處理

BeanPostProcessor的postProcessAfterInitialization方法

@Component
public class CustomBeanPostProcessor implements BeanPostProcessor {
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (bean instanceof ExampleBean) {
            System.out.println("6. BeanPostProcessor后置處理 - " + beanName);
        }
        return bean;
    }
}

7. Bean使用階段

Bean完全初始化，可供應(yīng)用程序使用

@Service
public class BusinessService {
    private final ExampleBean exampleBean;
    public BusinessService(ExampleBean exampleBean) {
        this.exampleBean = exampleBean;
    }
    public void doBusiness() {
        System.out.println("7. Bean使用階段 - 執(zhí)行業(yè)務(wù)邏輯");
    }
}

8. 銷毀階段

@PreDestroy注解方法

public class ExampleBean {
    @PreDestroy
    public void preDestroy() {
        System.out.println("8.1 @PreDestroy方法執(zhí)行");
    }
}

DisposableBean接口

public class ExampleBean implements DisposableBean {
    @Override
    public void destroy() throws Exception {
        System.out.println("8.2 DisposableBean.destroy()執(zhí)行");
    }
}

自定義destroy方法

public class ExampleBean {
    public void customDestroy() {
        System.out.println("8.3 自定義destroy方法執(zhí)行");
    }
}
// 配置類中指定destroy方法
@Configuration
public class AppConfig {
    @Bean(destroyMethod = "customDestroy")
    public ExampleBean exampleBean() {
        return new ExampleBean();
    }
}

完整示例代碼

1. 定義Bean類

import org.springframework.beans.factory.*;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
public class LifecycleBean implements BeanNameAware, BeanFactoryAware, 
        ApplicationContextAware, InitializingBean, DisposableBean {
    private String name;
    private AnotherBean anotherBean;
    public LifecycleBean() {
        System.out.println("1. 構(gòu)造函數(shù)執(zhí)行 - Bean實(shí)例化");
    }
    public void setName(String name) {
        System.out.println("2. 屬性注入 - name: " + name);
        this.name = name;
    }
    public void setAnotherBean(AnotherBean anotherBean) {
        System.out.println("2. 依賴注入 - anotherBean");
        this.anotherBean = anotherBean;
    }
    @Override
    public void setBeanName(String name) {
        System.out.println("3. BeanNameAware - Bean名稱: " + name);
    }
    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        System.out.println("3. BeanFactoryAware - BeanFactory注入");
    }
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        System.out.println("3. ApplicationContextAware - ApplicationContext注入");
    }
    @PostConstruct
    public void postConstruct() {
        System.out.println("5.1 @PostConstruct方法執(zhí)行");
    }
    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("5.2 InitializingBean.afterPropertiesSet()執(zhí)行");
    }
    public void customInit() {
        System.out.println("5.3 自定義init方法執(zhí)行");
    }
    public void doSomething() {
        System.out.println("7. Bean使用階段 - 執(zhí)行業(yè)務(wù)方法");
    }
    @PreDestroy
    public void preDestroy() {
        System.out.println("8.1 @PreDestroy方法執(zhí)行");
    }
    @Override
    public void destroy() throws Exception {
        System.out.println("8.2 DisposableBean.destroy()執(zhí)行");
    }
    public void customDestroy() {
        System.out.println("8.3 自定義destroy方法執(zhí)行");
    }
}

2. 配置BeanPostProcessor

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.stereotype.Component;
@Component
public class CustomBeanPostProcessor implements BeanPostProcessor {
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        if (bean instanceof LifecycleBean) {
            System.out.println("4. BeanPostProcessor前置處理 - " + beanName);
        }
        return bean;
    }
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (bean instanceof LifecycleBean) {
            System.out.println("6. BeanPostProcessor后置處理 - " + beanName);
        }
        return bean;
    }
}

3. 配置類

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class AppConfig {
    @Bean(initMethod = "customInit", destroyMethod = "customDestroy")
    public LifecycleBean lifecycleBean() {
        LifecycleBean bean = new LifecycleBean();
        bean.setName("示例Bean");
        return bean;
    }
    @Bean
    public AnotherBean anotherBean() {
        return new AnotherBean();
    }
}

4. 測試類

import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class LifecycleTest {
    public static void main(String[] args) {
        System.out.println("Spring容器啟動(dòng)...");
        AnnotationConfigApplicationContext context = 
            new AnnotationConfigApplicationContext(AppConfig.class);
        System.out.println("\n獲取Bean并執(zhí)行業(yè)務(wù)方法...");
        LifecycleBean bean = context.getBean(LifecycleBean.class);
        bean.doSomething();
        System.out.println("\nSpring容器關(guān)閉...");
        context.close();
        System.out.println("程序結(jié)束");
    }
}

生命周期流程圖

Bean生命周期完整流程：
1. 實(shí)例化 → 2. 屬性賦值 → 3. Aware接口回調(diào) → 4. BeanPostProcessor前置處理 →
5. 初始化(@PostConstruct → InitializingBean → 自定義init) → 6. BeanPostProcessor后置處理 →
7. Bean就緒可用 → 8. 銷毀(@PreDestroy → DisposableBean → 自定義destroy)