spring注解驱动开发6-Spring的生命周期

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(1). Bean 的创立

bean 的创立实际上就是指 构造方法的调用;

singleton(单例)bean - 容器初始化时会事后调用, 除非标注了 @Lazy 注解指定懒加载 (提早创立);

prototype(原型)bean - 当第一次调用 getBean 办法时, 才会调用构造方法

(2). Bean 的初始化和销毁 - 4 种办法

bean 的初始化, 指的是在构造方法调用之后, 对象的一些初始化操作;

bean 的销毁, 指的是在 spring 容器敞开前, 对 bean 对象做的一些后续解决操作的调用;

Bean 的初始化和销毁有一下几种办法:

(2.1) @Bean 注解指定 initMethod/destroyMethod;

bean: 一般 java 类, 其中定义了 办法名: init close

package com.niewj.bean;

public class LifeTestBean1 {
    private String value;

    public LifeTestBean1(String value){System.out.println("LifeTestBean1- 初始化!");
        this.value = value;
    }

    public void init(){System.out.println("LifeTestBean1#init- 调用!");
    }

    public void close(){System.out.println("LifeTestBean1#close- 调用!");
    }
}

Life1Config 配置类中: 通过 @Bean 的属性 指定了初始化和销毁办法:

  • initMethod=”init”
  • destroyMethod=”close”
package com.niewj.config;

import com.niewj.bean.LifeTestBean1;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class Life1Config {@Bean(value = "lifeBean1", initMethod = "init", destroyMethod = "close")
    public LifeTestBean1 lifeTestBean(){return  new LifeTestBean1("bean1");
    }
}

测试用例: testLifecycle

package com.niewj;

import com.niewj.bean.LifeTestBean1;
import com.niewj.config.Life1Config;
import org.junit.Test;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import java.util.stream.Stream;

/**
 * spring 生命周期.
 */
public class LifecycleTest {

    @Test
    public void testLifecycle() {AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(Life1Config.class);

        // 打印 spring 容器中的 BeanDefinition
        Stream.of(ctx.getBeanDefinitionNames()).forEach(e-> System.out.println(e));
        System.out.println("=============================");
        LifeTestBean1 bean = ctx.getBean(LifeTestBean1.class);

        System.out.println(bean);

        ctx.close();}
}

​ 能够看到:

  • 构造方法会事后调用 (单例 bean);
  • 而后 init 办法被调用;
  • 最初上下文敞开时, close 办法也被调用!
LifeTestBean1- 初始化!
LifeTestBean1#init- 调用!
org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
org.springframework.context.event.internalEventListenerProcessor
org.springframework.context.event.internalEventListenerFactory
life1Config
lifeBean1
=============================
com.niewj.bean.LifeTestBean1@7d3a22a9
LifeTestBean1#close- 调用!

(2.2) InitializingBean/DisposableBean 接口;

bean: LifeTestBean2 implements InitializingBean, DisposableBean

package com.niewj.bean;

import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;

/**
 * 实现 InitializingBean && DisposableBean
 */
public class LifeTestBean2 implements InitializingBean, DisposableBean {
    private String value;

    public LifeTestBean2(String value){System.out.println("LifeTestBean2- 初始化!");
        this.value = value;
    }

    @Override
    public void destroy() throws Exception {System.out.println("LifeTestBean2#DisposableBean#destroy- 调用!");
    }

    @Override
    public void afterPropertiesSet() throws Exception {System.out.println("LifeTestBean2#InitializingBean#afterPropertiesSet- 调用!");
    }
}

配置类: Life2Config:

package com.niewj.config;

import com.niewj.bean.LifeTestBean2;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class Life2Config {

    @Bean
    public LifeTestBean2 lifeTestBean(){return  new LifeTestBean2("bean2");
    }
}

测试用例:

    @Test
    public void testLifecycle2() {
        // 1. 通过 bean 实现 InitializingBean 和 DisposableBean 接口
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(Life2Config.class);

        // 打印 spring 容器中的 BeanDefinition
        Stream.of(ctx.getBeanDefinitionNames()).forEach(e-> System.out.println(e));
        System.out.println("=============================");
        LifeTestBean2 bean = ctx.getBean(LifeTestBean2.class);

        System.out.println(bean);

        ctx.close();}

output:

  • 构造方法调用 (singleton 容器事后初始化);
  • InitializingBean#afterPropertiesSet 调用;
  • 工厂敞开前: DisposableBean#destroy 调用;
LifeTestBean2- 初始化!
LifeTestBean2#InitializingBean#afterPropertiesSet- 调用!
org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
org.springframework.context.event.internalEventListenerProcessor
org.springframework.context.event.internalEventListenerFactory
life2Config
lifeTestBean
=============================
com.niewj.bean.LifeTestBean2@7d3a22a9
LifeTestBean2#DisposableBean#destroy- 调用!

(2.3) @PostConstruct/@PreDestroy 注解 (JSR250);

bean: LifeTestBean3 注解: @PreDestroy PostConstruct

package com.niewj.bean;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;

/**
 * 通过 JSR250 注解 @PostConstruct && @PreDestroy
 */
public class LifeTestBean3 {
    private String value;

    public LifeTestBean3(String value) {System.out.println("LifeTestBean3- 初始化!");
        this.value = value;
    }

    @PreDestroy
    public void doDestroy() {System.out.println("LifeTestBean3#doDestroy- 调用!");
    }

    @PostConstruct
    public void doInit() {System.out.println("LifeTestBean3#doInit- 调用!");
    }
}

配置类:

package com.niewj.config;

import com.niewj.bean.LifeTestBean3;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class Life3Config {

    @Bean
    public LifeTestBean3 lifeTestBean() {return new LifeTestBean3("bean3");
    }
}

测试用例:

    @Test
    public void testLifecycle3() {
        // 1. 通过 JSR250 注解 @PostConstruct && @PreDestroy
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(Life3Config.class);

        // 打印 spring 容器中的 BeanDefinition
        Stream.of(ctx.getBeanDefinitionNames()).forEach(e-> System.out.println(e));
        System.out.println("=============================");
        LifeTestBean3 bean = ctx.getBean(LifeTestBean3.class);

        System.out.println(bean);

        ctx.close();}

output:

  • 构造方法调用;
  • @PostConstruct 标注的办法调用;
  • 上下文敞开时; @PreDestroy 标注的办法被调用;
LifeTestBean3- 初始化!
LifeTestBean3#doInit- 调用!
org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
org.springframework.context.event.internalEventListenerProcessor
org.springframework.context.event.internalEventListenerFactory
life3Config
lifeTestBean
=============================
com.niewj.bean.LifeTestBean3@2a32de6c
LifeTestBean3#doDestroy- 调用!

(2.4) BeanPostProcessor 接口 (作用范围广);

此接口对所有扫描到的 bean 都起作用:

实现: BeanPostProcessor 接口:

  • before-init : postProcessBeforeInitialization(Object bean, String beanName)
  • after-init: postProcessAfterInitialization(Object bean, String beanName)
package com.niewj.bean;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.stereotype.Component;

/**
 * 通过 BeanPostProcessor 接口
 */
@Component
public class MyBeanPostProcessor implements BeanPostProcessor {public MyBeanPostProcessor() {System.out.println("MyBeanPostProcessor- 初始化!");
    }

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {System.out.println("MyBeanPostProcessor#postProcessBeforeInitialization- 调用!->beanName=" + beanName + "; bean=" + bean);
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {System.out.println("MyBeanPostProcessor#postProcessAfterInitialization- 调用!->beanName=" + beanName + "; bean=" + bean);
        return bean;
    }
}

com.niewj.bean 包下一个一般类:

package com.niewj.bean;

import org.springframework.stereotype.Component;

/**
 * 一般 bean+@Component
 */
@Component
public class LifeTestBean4 {public LifeTestBean4() {System.out.println("LifeTestBean4- 初始化!");
    }
}

配置类: Life4Config:

扫描范畴: @ComponentScan(“com.niewj.bean”)

包含: LifeTestBean4.java && MyBeanPostProcessor.java

package com.niewj.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan("com.niewj.bean")
public class Life4Config {}

用例: 注册配置类: Life4Config

    @Test
    public void testLifecycle4() {
        // 1. 通过 实现 BeanPostProcesser 接口
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(Life4Config.class);

        // 打印 spring 容器中的 BeanDefinition
        Stream.of(ctx.getBeanDefinitionNames()).forEach(e-> System.out.println(e));
        System.out.println("=============================");

        ctx.close();}

output: 察看控制台:

MyBeanPostProcessor: postProcessBeforeInitialization/postProcessAfterInitialization

LifeTestBean4: postProcessBeforeInitialization/postProcessAfterInitialization

MyBeanPostProcessor- 初始化!
MyBeanPostProcessor#postProcessBeforeInitialization- 调用!->beanName=life4Config; bean=com.niewj.config.Life4Config$$EnhancerBySpringCGLIB$$684530bf@27c86f2d
MyBeanPostProcessor#postProcessAfterInitialization- 调用!->beanName=life4Config; bean=com.niewj.config.Life4Config$$EnhancerBySpringCGLIB$$684530bf@27c86f2d
LifeTestBean4- 初始化!
MyBeanPostProcessor#postProcessBeforeInitialization- 调用!->beanName=lifeTestBean4; bean=com.niewj.bean.LifeTestBean4@197d671
MyBeanPostProcessor#postProcessAfterInitialization- 调用!->beanName=lifeTestBean4; bean=com.niewj.bean.LifeTestBean4@197d671
org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
org.springframework.context.event.internalEventListenerProcessor
org.springframework.context.event.internalEventListenerFactory
life4Config
lifeTestBean4
myBeanPostProcessor
=============================

(2.5) bean 的初始化小结

初始化和销毁有四种形式:

1. @Bean 注解指定属性 initMethod/destroyMethod;

2. 一般 bean 实现 InitializingBean/DisposableBean 接口;

3. 一般 bean 办法上标注 @PostConstruct/@PreDestroy 注解;

4. 通用办法: 实现接口 BeanPostProcessor;

(2.6) 问题来了: 4 种形式的优先级程序是如何的?

上实例: LifeTestBeanAll.java

其中蕴含:

1.@PostConstruct/@PreDestroy 注解;

2.InitializingBean, DisposableBean 接口的实现;

3.@Bean 指定 initMethod/destroyMethod 办法;

4.MyBeanPostProcessor 实现 (在下方);

package com.niewj.bean;

import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;

/**
 * 一般 bean+@Component
 */
@Component
public class LifeTestBeanAll implements InitializingBean, DisposableBean {public LifeTestBeanAll() {System.out.println("LifeTestBeanAll 构造方法调用!");
    }

    @PostConstruct
    public void postConstruct(){System.out.println("LifeTestBeanAll#@PostConstruct 调用");
    }

    @PreDestroy
    public void preDestroy(){System.out.println("LifeTestBeanAll#@PreDestroy 调用");
    }

    public void init(){System.out.println("LifeTestBeanAll#@Bean(initMethod) 调用");
    }

    public void close(){System.out.println("LifeTestBeanAll#@Bean(destroyMethod) 调用");
    }

    @Override
    public void destroy() throws Exception {System.out.println("LifeTestBeanAll#Disposable 调用~~");
    }

    @Override
    public void afterPropertiesSet() throws Exception {System.out.println("LifeTestBeanAll#InitializingBean# 调用!~");
    }
}

MyBeanPostProcessor:

package com.niewj.bean;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.stereotype.Component;

/**
 * 通过 BeanPostProcessor 接口
 */
@Component
public class MyBeanPostProcessor implements BeanPostProcessor {public MyBeanPostProcessor() {System.out.println("MyBeanPostProcessor- 初始化!");
    }

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {System.out.println("MyBeanPostProcessor#postProcessBeforeInitialization- 调用!->beanName=" + beanName + "; bean=" + bean);
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {System.out.println("MyBeanPostProcessor#postProcessAfterInitialization- 调用!->beanName=" + beanName + "; bean=" + bean);
        return bean;
    }
}

配置类:

package com.niewj.config;

import com.niewj.bean.LifeTestBeanAll;
import com.niewj.bean.User;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan("com.niewj.bean")
public class LifeAllConfig {@Bean(initMethod = "init", destroyMethod = "close")
    public LifeTestBeanAll lifeTestBeanAll(){return new LifeTestBeanAll();
    }
}

测试用例:

    @Test
    public void testLifecycleAll() {
        // 正文掉 LifeTestBean4#@Component 以防烦扰
        // 1. 通过 实现 BeanPostProcesser 接口
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(LifeAllConfig.class);

        // 打印 spring 容器中的 BeanDefinition
        Stream.of(ctx.getBeanDefinitionNames()).forEach(e-> System.out.println(e));
        System.out.println("=============================");

        ctx.close();}

output: 要害中央来了:

MyBeanPostProcessor- 初始化!
MyBeanPostProcessor#postProcessBeforeInitialization- 调用!->beanName=lifeAllConfig; bean=com.niewj.config.LifeAllConfig$$EnhancerBySpringCGLIB$$77052e36@3d121db3
MyBeanPostProcessor#postProcessAfterInitialization- 调用!->beanName=lifeAllConfig; bean=com.niewj.config.LifeAllConfig$$EnhancerBySpringCGLIB$$77052e36@3d121db3
LifeTestBeanAll 构造方法调用!
MyBeanPostProcessor#postProcessBeforeInitialization- 调用!->beanName=lifeTestBeanAll; bean=com.niewj.bean.LifeTestBeanAll@6b26e945
LifeTestBeanAll#@PostConstruct 调用
LifeTestBeanAll#InitializingBean# 调用!~
LifeTestBeanAll#@Bean(initMethod) 调用
MyBeanPostProcessor#postProcessAfterInitialization- 调用!->beanName=lifeTestBeanAll; bean=com.niewj.bean.LifeTestBeanAll@6b26e945
org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
org.springframework.context.event.internalEventListenerProcessor
org.springframework.context.event.internalEventListenerFactory
lifeAllConfig
lifeTestBeanAll
myBeanPostProcessor
=============================
LifeTestBeanAll#@PreDestroy 调用
LifeTestBeanAll#Disposable 调用~~
LifeTestBeanAll#@Bean(destroyMethod) 调用

剖析整顿: 只看 lifeTestBeanAll:

1.BeanPostProcessor#postProcessBeforeInitialization 首先调用;

2.@PostConstruct;

3.InitializingBean 接口实现;

4.@Bean(initMethod)

5.BeanPostProcessor#postProcessAfterInitialization 调用;

6.@PreDestroy

7.Disposable 接口实现

8.@Bean(destroyMethod)

初始化程序: BeanPostProcessor 的 before-init –> @PostConstruct 注解 –> InitializingBean 接口 –> @Bean 注解指定的 initMethod 办法 –>BeanPostProcessor 的 after-init;

destroy 的程序: @PreDestroy 注解 –> DisposableBean 接口 — > @Bean(destroyMethod)

(2.7) 源码剖析:doCreateBean

源码地位:

// org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#doCreateBean
doCreateBean(){...
    try {populateBean(beanName, mbd, instanceWrapper);
        exposedObject = initializeBean(beanName, exposedObject, mbd);
    }
...
}

1. populateBean: 为 bean 属性赋值等操作;

2. initializeBean: (上面时序图中的操作)

// org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#initializeBean(java.lang.String, java.lang.Object, org.springframework.beans.factory.support.RootBeanDefinition)
办法流程源码片段:
--- 办法名:
AbstractAutowireCapableBeanFactory#initializeBean(final String beanName, final Object bean, @Nullable RootBeanDefinition mbd)
(1). applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName)
    1. 遍历并调用 BeanPostProcessor#postProcessBeforeInitialization()
(2). invokeInitMethods(beanName, wrappedBean, mbd): 
    1. 调用 InitializingBean 接口的 afterPropertiesSet() 办法;
    2. 调用 invokeCustomInitMethod() --> @Bean(initMethod) 执行!
(3). applyBeanPostProcessorsAfterInitialization
    1. 调用 postProcessAfterInitialization()
2.1 applyBeanPostProcessorsBeforeInitialization
2.2 invokeInitMethods
2.3. applyBeanPostProcessorsAfterInitialization

时序图:

正文完
spring
发表至： spring
2020-07-14
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