spring入门（4）---spring中Bean的生命周期总结

spring中在ApplicationContext或在BeanFactory中Bean的生命周期总结

Spring中Bean的生命周期,在学习spring的过程中bean的生命周期理解对学习spring有很大的帮助，下面我就分别介绍在ApplicationContext和BeanFactory中Bean的生命周期。

1、在ApplicationContext中Bean的生命周期

生命周期执行的过程如下：

1、需找所有的bean根据bean定义的信息来实例化bean

2、使用依赖注入，spring按bean定义信息配置bean的所有属性

3、若bean实现了BeanNameAware接口，工厂调用Bean的setBeanName（）方法传递bean的ID。

4、若bean实现了BeanFactoryAware接口，工厂调用setBeanFactory（） 方法传入工厂自身。

5、若bean实现了ApplicationContextAware()接口，setApplicationContext()方法会被调用

6、若BeanPostProcessor和bean关联,

则它们的postProcessBeforeInitialization()方法被调用

7、若bean指定了init-method="init"方法、，它将被调用。

8、若有BeanPostProcessor和bean关联，

则它们的postProcessAfterInitialization()方法被调用

注意：通过已上操作,此时的Bean就可以被应用的系统使用，并讲保留在BeanFactory工厂中直到不再需要为止.但我们也可以通过9或者10进行销毁

9、若bean实现了DisposableBean接口,distroy()方法被调用

10、如果指定了destroy-method="close"定制的销毁方法，就调用这个方法

案例分析：

创建一个实体Bean代码如下：

[java]
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package www.csdn.spring.dao;


import org.springframework.beans.BeansException;

import org.springframework.beans.factory.BeanFactory;

import org.springframework.beans.factory.BeanFactoryAware;

import org.springframework.beans.factory.BeanNameAware;

import org.springframework.beans.factory.DisposableBean;

import org.springframework.beans.factory.InitializingBean;

import org.springframework.context.ApplicationContext;

import org.springframework.context.ApplicationContextAware;


public class HelloDaoImpl implements BeanNameAware, BeanFactoryAware,

InitializingBean, ApplicationContextAware, DisposableBean {


private String content;


public HelloDaoImpl() {

System.out.println("----------HelloDaoImpl实例化");

}


public void setContent(String content) {

System.out.println("----------通过依赖注入的内容是:" + content);

this.content = content;

}


@Override

public void setBeanName(String beanId) {

System.out.println("----------输出BeanId:" + beanId);

}


@Override

public void setBeanFactory(BeanFactory factory) throws BeansException {

System.out.println("----------factory:" + factory.getClass());


}


@Override

public void setApplicationContext(ApplicationContext applicationContext)

throws BeansException {

System.out.println("----------" + applicationContext);


}


@Override

public void afterPropertiesSet() throws Exception {

System.out.println("----------afterPropertiesSet");

}


public void init() {

System.out.println("----------初始化方法");

}


@Override

public void destroy() throws Exception {

System.out.println("----------bean被销毁");


}


public void close() {

System.out.println("----------close");

}


}

package www.csdn.spring.dao;

import org.springframework.beans.BeansException;

import org.springframework.beans.factory.BeanFactory;

import org.springframework.beans.factory.BeanFactoryAware;

import org.springframework.beans.factory.BeanNameAware;

import org.springframework.beans.factory.DisposableBean;

import org.springframework.beans.factory.InitializingBean;

import org.springframework.context.ApplicationContext;

import org.springframework.context.ApplicationContextAware;

public class HelloDaoImpl implements BeanNameAware, BeanFactoryAware,

InitializingBean, ApplicationContextAware, DisposableBean {

private String content;

public HelloDaoImpl() {

System.out.println("----------HelloDaoImpl实例化");

}

public void setContent(String content) {

System.out.println("----------通过依赖注入的内容是:" + content);

this.content = content;

}

@Override

public void setBeanName(String beanId) {

System.out.println("----------输出BeanId:" + beanId);

}

@Override

public void setBeanFactory(BeanFactory factory) throws BeansException {

System.out.println("----------factory:" + factory.getClass());

}

@Override

public void setApplicationContext(ApplicationContext applicationContext)

throws BeansException {

System.out.println("----------" + applicationContext);

}

@Override

public void afterPropertiesSet() throws Exception {

System.out.println("----------afterPropertiesSet");

}

public void init() {

System.out.println("----------初始化方法");

}

@Override

public void destroy() throws Exception {

System.out.println("----------bean被销毁");

}

public void close() {

System.out.println("----------close");

}

}

创建BeanPostProcessor实现类

[java]
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package www.csdn.spring.dao;


import org.springframework.beans.BeansException;

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


public class BeanPostProcessorImpl implements BeanPostProcessor {

@Override

public Object postProcessBeforeInitialization(Object bean, String beanName)

throws BeansException {

System.out.println("我把:" + beanName + "实例化化之前的操作");

return bean;

}


@Override

public Object postProcessAfterInitialization(Object bean, String beanName)

throws BeansException {

System.out.println("我把:" + beanName + "实例化化之后的操作");

return bean;

}


}

package www.csdn.spring.dao;

import org.springframework.beans.BeansException;

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

public class BeanPostProcessorImpl implements BeanPostProcessor {

@Override

public Object postProcessBeforeInitialization(Object bean, String beanName)

throws BeansException {

System.out.println("我把:" + beanName + "实例化化之前的操作");

return bean;

}

@Override

public Object postProcessAfterInitialization(Object bean, String beanName)

throws BeansException {

System.out.println("我把:" + beanName + "实例化化之后的操作");

return bean;

}

}

在配置文件中配置实体Bean和BeanPostProcessorImpl 特殊的Bean

[html]
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<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans.xsd">



<!-- spring容器 就是负责创建、管理、维护Bean 并且能够依赖注入到相应组件上 -->

<bean id="helloDaoImpl" class="www.csdn.spring.dao.HelloDaoImpl"

scope="singleton" lazy-init="false" init-method="init" destroy-method="close">

<!-- 通过set方法注入 -->

<property name="content" value="陈老师早上好！" />

</bean>


<!-- BeanPostProcessor与当前的bean都进行关联 -->

<bean class="www.csdn.spring.dao.BeanPostProcessorImpl" />


</beans>

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://www.springframework.org/schema/beans

           http://www.springframework.org/schema/beans/spring-beans.xsd"> 
<!-- spring容器 就是负责创建、管理、维护Bean 并且能够依赖注入到相应组件上 -->

<bean id="helloDaoImpl" class="www.csdn.spring.dao.HelloDaoImpl"

scope="singleton" lazy-init="false" init-method="init" destroy-method="close">

<!-- 通过set方法注入 -->

<property name="content" value="陈老师早上好！" />

</bean>

<!-- BeanPostProcessor与当前的bean都进行关联 -->

<bean class="www.csdn.spring.dao.BeanPostProcessorImpl" />

</beans>

创建测试类BeanTest

[java]
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package www.csdn.spring.bean.cycle;


import org.junit.Test;

import org.springframework.context.ApplicationContext;

import org.springframework.context.ConfigurableApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;


public class BeanTest {


@Test

public void test() {

ApplicationContext context = new ClassPathXmlApplicationContext(

"classpath:spring-dao.xml");

// 强制造型

ConfigurableApplicationContext cont = (ConfigurableApplicationContext) context;

// 执行关闭 可以考到 destory-method的方法的执行

cont.close();


}

}

package www.csdn.spring.bean.cycle;

import org.junit.Test;

import org.springframework.context.ApplicationContext;

import org.springframework.context.ConfigurableApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class BeanTest {

@Test

public void test() {

ApplicationContext context = new ClassPathXmlApplicationContext(

"classpath:spring-dao.xml");

// 强制造型

ConfigurableApplicationContext cont = (ConfigurableApplicationContext) context;

// 执行关闭 可以考到 destory-method的方法的执行

cont.close();

}

}

执行结果如下：



总结：在ApplicationContext中Bean的生命周期



2、在 BeanFactory中Bean的生命周期

在BeanFactory中Bean的生命周期与ApplicationContext中bean的生命周期唯一不同的是：若bean实现了ApplicationContextAware()接口，在ApplicationContext中bean的生命周期中setApplicationContext()方法会被调用,而在BeanFactory中Bean的生命周期此方法不会被调用。

案例采用上个案例：测试类中测试代码如下：

[java]
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// 创建资源对象

ClassPathResource resource = new ClassPathResource("spring-dao.xml");

// 采用BeanFactory初始化容器

ConfigurableBeanFactory cbf = new XmlBeanFactory(resource);

// bean后置处理器必须通过addBeanPostProcessor(new BeanPostProcessorImpl())手动添加


cbf.addBeanPostProcessor(new BeanPostProcessorImpl());

//在配置文件中给BeanPostProcessorImpl的bean加上id="beanPostProcessorImpl" //cbf.addBeanPostProcessor(cbf.getBean("beanPostProcessorImpl", BeanPostProcessorImpl.class));


// 获取Bean对象

cbf.getBean("helloDaoImpl", HelloDaoImpl.class);

// 销毁

cbf.destroySingletons();

// 创建资源对象

ClassPathResource resource = new ClassPathResource("spring-dao.xml");

// 采用BeanFactory初始化容器

ConfigurableBeanFactory cbf = new XmlBeanFactory(resource);

// bean后置处理器必须通过addBeanPostProcessor(new BeanPostProcessorImpl())手动添加

cbf.addBeanPostProcessor(new BeanPostProcessorImpl());

//在配置文件中给BeanPostProcessorImpl的bean加上id="beanPostProcessorImpl" //cbf.addBeanPostProcessor(cbf.getBean("beanPostProcessorImpl", BeanPostProcessorImpl.class));

// 获取Bean对象

cbf.getBean("helloDaoImpl", HelloDaoImpl.class);

// 销毁

cbf.destroySingletons();

执行结果：



总结：在BeanFactory中Bean的生命周期



另外说明：

应用上下文与bean工厂的另一个重要区别是关于单例bean如何被加载。

bean工厂延迟加载所有bean，直到getBean()方法被调用。

应用上下文会在启动后预载入所有单例bean.这样可确保应用不需要等待他们被创建。