深度解析Spring Bean生命周期的各个阶段

2025-09-24 11:30 开发作者：猿究院-陆昱泽

概述

Spring Bean的生命周期是Spring框架的核心概念之一，理解Bean从创建到销毁的整个过程对于开发高质量的Spring应用程序至关重要。本文将详细梳理Spring Bean生命周期的各个阶段，并通过代码示例展示每个关键节点。

Spring Bean生命周期阶段

1. 实例化阶段

Spring容器通过构造函数或工厂方法创建Bean实例

public class ExampleBean {
    public ExampleBean() {
        System.out.println("1. Bean实例化 - 构造函数执行");
    }
}

2. 属性赋值阶段

Spring容器注入Bean的属性和依赖

public class ExampleBean {
    private String name;
   http://www.devze.com private AnotherBean anotherBean;
    // Setter方法用于属性注入
    public void setName(String name) {
        System.out.println("2. 属性注入 - name: " + name);
        this.name = name;
    }
    public void setAnotherBean(AnotherBean anotherBean) {
        System.out.println("2. 依赖注入 - anotherBean");
        this.anotherBean = anotherBean;
    }
}

3. Aware接口回调阶段

Bean实现Aware接口获取容器资源

public class ExampleBean implements BeanNameAware, BeanFactoryAware, ApplicationContextAware {
    @Override
    public void setBeanName(String name) {
        System.out.println("3. BeanNameAware - Bean名称: " + 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前置处理

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前置处理 - " + beanName);
        }
        return bean;
    }
}

5. 初始化阶段

@PostConstruct注解方法

public class ExampleBean {
    @PostConstruct
    public void postConstruct() {
        System.out.println("5.1 @PostConstruct方法执行");
    }
}

InitializingBean接口

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

自定义init方法

public class ExampleBean {
    public void customInit() {
        System.out.println("5.3 自定义init方法执行");
    }
}
// 配置类中指定init方法
@Configuration
public class AppConfig {
    @Bean(initMethod = "customInit")
    public ExampleBean exampleBean() {
        return new ExampleBean();
    }
}

6. BeanPostProcessor后置处理

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后置处理 - " + beanName);
        }
        return bean;
    }
}

7. Bean使用阶段

Bean完全初始化，可供应用程序使用

@Service
public class BusinessService {
    private final ExampleBean exampleBean;
    public BusinessService(ExampleBean exampleBean) {
        this.exampleBean = exampleBean;
    }
    public void doBusiness() {
        System.out.println("7. Bean使用阶段 - 执行业务逻辑");
    }
}

8. 销毁阶段

@PreDestroy注解方法

public class ExampleBean {
    @PreDestroy
    public void preDestroy() {
        System.out.println("8.1 @PreDestroy方法执行");
    }
}

DisposableBean接口

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

自定义destroy方法

public class ExampleBean {
    public void customDestroy() {
        System.out.println("8.3 自定义destroy方法执行");
    }
}
// 配置类中指定destroy方法
@Configuration
public class AppConfig {
    @Bean(destroyMethod = "customDestroy")
    public ExampleBean exampleBean() {
        return new ExampleBean();
    }
}

完整示例代码

1. 定义Bean类

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编程客栈 anotherBean;
    public LifecycleBean() {
        System.out.println("1. 构造函数执行 - Bean实例化");
    }
    public void setName(String name) {
        System.out.println("2. 属性注入 - name: " + name);
        this.name = name;
    }
    public void setAnotherBean(AnotherBean anotherBean) {
        System.out.println("2. 依赖注入 - anotherBean");
        this.anotherBean = anotherBean;
    }
    @Override
    public void setBeanName(String name) {
        System.out.println("3. BeanNameAware - Bean名称: " + 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方法执行");
    }
    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("5.2 InitializingBean.afterPropertiesSet()执行");
    }
    public void customInit() {
        System.out.println("5.3 自定义init方法执行");
    }
    public void DOSomething() {
        System.out.println("7. Bean使用阶段 - 执行业务方法");
    }
    @PreDestroy
    public void preDestroy() {
        System.out.println("8.1 @PreDestroy方法执行");
    }
    @Override
    public void destroy() throws Exception {
        System.out.println("8.2 DisposableBean.destroy()执行");
    }
    public void customDestroy() {
        System.out.println("8.3 自定义destroy方法执行");
    }
}

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) {
       www.devze.com     System.out.println("4. BeanPostProcessor前置处理 - " + beanName);
        }
        return bean;
    }
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (bean instanceof LifecycleBean) {
            System.out.println("6. BeanPostProcessor后置处理 - " + beanName);
        }
       js return bean;
    }
}

3. 配置类

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. 测试类

import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class LifecycleTest {
    public static void main(String[] args) {
        System.out.println("Spring容器启动...");
        AnnotationConfigApplicationContext context = 
            new AnnotationConfigApplicationContext(AppConfig.class);
        System.out.println("\n获取Bean并执行业务方法...");
        LifecycleBean bean = context.getBean(LifecycleBean.class);
        bean.doSomething();
        System.out.println("\nSpring容器关闭...");
        context.close();
        System.out.println("程序结束");
    }
}

生命周期流程图

Bean生命周期完整流程：
1. 实例化 → 2. 属性赋值 → 3. Aware接口回调 → 4. BeanPostProcessor前置处理 →
5. 初始化(@PostConstruct → InitializingBean → 自定义init) → 6. BeanPostProcessor后置处理 →
7. Bean就绪可用 → 8. 销毁(@PreDestroy → DisposableBean → 自定义destroy)

总结

Spring Bean的生命周期是一个复杂但有序的过程，理解每个阶段的执行顺序和用途对于：

调试和问题排查：能够快速定位Bean初始化相关的问题
扩展功能：通过BeanPostProcessor等机制扩展Spring功能
资源管理：正确管理数据库连接、线程池等资源
性能优化：合理使用各种初始化机制提升应用性能

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继续阅读：Spring Bean生命周期

深度解析Spring Bean生命周期的各个阶段

目录

概述

Spring Bean生命周期阶段

1. 实例化阶段

2. 属性赋值阶段

3. Aware接口回调阶段

4. BeanPostProcessor前置处理

5. 初始化阶段

@PostConstruct注解方法

InitializingBean接口

自定义init方法

6. BeanPostProcessor后置处理

7. Bean使用阶段

8. 销毁阶段

@PreDestroy注解方法

DisposableBean接口

自定义destroy方法

完整示例代码

1. 定义Bean类

2. 配置BeanPostProcessor

3. 配置类

4. 测试类

生命周期流程图

总结

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