在Spring中一个bean的生命周期为 构造--> 初始化-->销毁
1.构造（对象创建）
单实例：在容器启动的时候创建
多实例：在每次获取的时候创建
2.初始化
对象创建完成，并赋值好，调用初始化方法
3.销毁
单实例：容器关闭的时候
多实例：容器不会管理这个bean，容器不会调用销毁方法
代码示例
创建Car 类
public class Car {
public void init() {
System.out.println("创建一个car");
}
public void destroy() {
System.out.println("销毁一个car");
}
}
创建配置配置类，容器定义car (
)
@Configuration
public class MainConfigOfLifeCycle {
//@Scope("prototype")
@Bean(initMethod = "init",destroyMethod = "destroy")
public Car car() {
return new Car();
}
}
创建配置配置类，容器定义car (
)
@Configuration
public class MainConfigOfLifeCycle {
@Scope("prototype")
@Bean(initMethod = "init",destroyMethod = "destroy")
public Car car() {
return new Car();
}
}
创建测试类
public class IocTestLifeCycle {
public static void main(String[] args) {
AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfigOfLifeCycle.class);
//printBeans(applicationContext);
applicationContext.getBean("car");
applicationContext.close();
}
分析控制台输出
当单例模式的时候,在容器创建的时候car 就被创建完成并被初始化完成，容器关闭的时候applicationContext.close();car对象被销毁，容器不关闭car对象不销毁
创建一个car
16:05:24.959 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Finished creating instance of bean 'car'
16:05:24.960 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'org.springframework.context.event.internalEventListenerFactory'
16:05:24.978 [main] DEBUG org.springframework.context.annotation.AnnotationConfigApplicationContext - Unable to locate LifecycleProcessor with name 'lifecycleProcessor': using default [org.springframework.context.support.DefaultLifecycleProcessor@2d7275fc]
16:05:24.978 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'lifecycleProcessor'
16:05:24.982 [main] DEBUG org.springframework.core.env.PropertySourcesPropertyResolver - Could not find key 'spring.liveBeansView.mbeanDomain' in any property source
16:05:24.984 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'car'
16:05:24.984 [main] INFO org.springframework.context.annotation.AnnotationConfigApplicationContext - Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@3551a94: startup date [Sun Mar 01 16:05:24 CST 2020]; root of context hierarchy
16:05:24.984 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'lifecycleProcessor'
16:05:24.985 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@58c1670b: defining beans [org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.event.internalEventListenerProcessor,org.springframework.context.event.internalEventListenerFactory,mainConfigOfLifeCycle,car]; root of factory hierarchy
16:05:24.985 [main] DEBUG org.springframework.beans.factory.support.DisposableBeanAdapter - Invoking destroy method 'destroy' on bean with name 'car'
销毁一个car
当多实例的时候,在获取car 的时候创建car对象，即使容器关闭的时候car 也不会销毁
创建一个car
16:09:31.873 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Finished creating instance of bean 'car'
16:09:31.874 [main] INFO org.springframework.context.annotation.AnnotationConfigApplicationContext - Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@3551a94: startup date [Sun Mar 01 16:09:31 CST 2020]; root of context hierarchy
16:09:31.874 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'lifecycleProcessor'
16:09:31.874 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@58c1670b: defining beans [org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.event.internalEventListenerProcessor,org.springframework.context.event.internalEventListenerFactory,mainConfigOfLifeCycle,car]; root of factory hierarchy
这里的销毁只是指调用我们的destroy方法，对象的销毁最后还是要交给jvm 的垃圾回收
再顺便提一句 spring的对象最终还是放在spring的一个大map 中，而这个map对象又和GC Roots相关联，而垃圾回收的可达性算法来说这个map一直可达，只要bean 对象还在map中就不会被垃圾回收，如果说的不对请留言指正，我就是做个笔记
