转载：Spring Bean的生命周期

一、生命周期流程图：

Spring Bean的完整生命周期从创建Spring容器开始，直到最终Spring容器销毁Bean，这其中包含了一系列关键点。

若容器注册了以上各种接口，程序那么将会按照以上的流程进行。下面将仔细讲解各接口作用。

二、各种接口方法分类

Bean的完整生命周期经历了各种方法调用，这些方法可以划分为以下几类：

1、Bean自身的方法　　：　　这个包括了Bean本身调用的方法和通过配置文件中<bean>的init-method和destroy-method指定的方法

2、Bean级生命周期接口方法　　：　　这个包括了BeanNameAware、BeanFactoryAware、InitializingBean和DiposableBean这些接口的方法

3、容器级生命周期接口方法　　：　　这个包括了InstantiationAwareBeanPostProcessor 和 BeanPostProcessor 这两个接口实现，一般称它们的实现类为“后处理器”。

4、工厂后处理器接口方法　　：　　这个包括了AspectJWeavingEnabler, ConfigurationClassPostProcessor, CustomAutowireConfigurer等等非常有用的工厂后处理器　　接口的方法。工厂后处理器也是容器级的。在应用上下文装配配置文件之后立即调用。

三、演示

我们用一个简单的Spring Bean来演示一下Spring Bean的生命周期。

1、首先是一个简单的Spring Bean，调用Bean自身的方法和Bean级生命周期接口方法，为了方便演示，它实现了BeanNameAware、BeanFactoryAware、InitializingBean和DiposableBean这4个接口，同时有2个方法，对应配置文件中<bean>的init-method和destroy-method。如下：

package springBeanTest;
 
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;
 
/**
 * @author qsk
 */
public class Person implements BeanFactoryAware, BeanNameAware,
        InitializingBean, DisposableBean {
 
    private String name;
    private String address;
    private int phone;
 
    private BeanFactory beanFactory;
    private String beanName;
 
    public Person() {
        System.out.println("【构造器】调用Person的构造器实例化");
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        System.out.println("【注入属性】注入属性name");
        this.name = name;
    }
 
    public String getAddress() {
        return address;
    }
 
    public void setAddress(String address) {
        System.out.println("【注入属性】注入属性address");
        this.address = address;
    }
 
    public int getPhone() {
        return phone;
    }
 
    public void setPhone(int phone) {
        System.out.println("【注入属性】注入属性phone");
        this.phone = phone;
    }
 
    @Override
    public String toString() {
        return "Person [address=" + address + ", name=" + name + ", phone="
                + phone + "]";
    }
 
    // 这是BeanFactoryAware接口方法
    @Override
    public void setBeanFactory(BeanFactory arg0) throws BeansException {
        System.out
                .println("【BeanFactoryAware接口】调用BeanFactoryAware.setBeanFactory()");
        this.beanFactory = arg0;
    }
 
    // 这是BeanNameAware接口方法
    @Override
    public void setBeanName(String arg0) {
        System.out.println("【BeanNameAware接口】调用BeanNameAware.setBeanName()");
        this.beanName = arg0;
    }
 
    // 这是InitializingBean接口方法
    @Override
    public void afterPropertiesSet() throws Exception {
        System.out
                .println("【InitializingBean接口】调用InitializingBean.afterPropertiesSet()");
    }
 
    // 这是DiposibleBean接口方法
    @Override
    public void destroy() throws Exception {
        System.out.println("【DiposibleBean接口】调用DiposibleBean.destory()");
    }
 
    // 通过<bean>的init-method属性指定的初始化方法
    public void myInit() {
        System.out.println("【init-method】调用<bean>的init-method属性指定的初始化方法");
    }
 
    // 通过<bean>的destroy-method属性指定的初始化方法
    public void myDestory() {
        System.out.println("【destroy-method】调用<bean>的destroy-method属性指定的初始化方法");
    }
}

　　2、接下来是演示BeanPostProcessor接口的方法，如下：

package springBeanTest;
 
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
 
public class MyBeanPostProcessor implements BeanPostProcessor {
 
    public MyBeanPostProcessor() {
        super();
        System.out.println("这是BeanPostProcessor实现类构造器！！");
        // TODO Auto-generated constructor stub
    }
 
    @Override
    public Object postProcessAfterInitialization(Object arg0, String arg1)
            throws BeansException {
        System.out
        .println("BeanPostProcessor接口方法postProcessAfterInitialization对属性进行更改！");
        return arg0;
    }
 
    @Override
    public Object postProcessBeforeInitialization(Object arg0, String arg1)
            throws BeansException {
        System.out
        .println("BeanPostProcessor接口方法postProcessBeforeInitialization对属性进行更改！");
        return arg0;
    }
}

如上，BeanPostProcessor接口包括2个方法postProcessAfterInitialization和postProcessBeforeInitialization，这两个方法的第一个参数都是要处理的Bean对象，第二个参数都是Bean的name。返回值也都是要处理的Bean对象。这里要注意。

3、InstantiationAwareBeanPostProcessor 接口本质是BeanPostProcessor的子接口，一般我们继承Spring为其提供的适配器类InstantiationAwareBeanPostProcessor Adapter来使用它，如下：

package springBeanTest;
 
import java.beans.PropertyDescriptor;
 
import org.springframework.beans.BeansException;
import org.springframework.beans.PropertyValues;
import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter;
 
public class MyInstantiationAwareBeanPostProcessor extends
        InstantiationAwareBeanPostProcessorAdapter {
 
    public MyInstantiationAwareBeanPostProcessor() {
        super();
        System.out
                .println("这是InstantiationAwareBeanPostProcessorAdapter实现类构造器！！");
    }
 
    // 接口方法、实例化Bean之前调用
    @Override
    public Object postProcessBeforeInstantiation(Class beanClass,
            String beanName) throws BeansException {
        System.out
                .println("InstantiationAwareBeanPostProcessor调用postProcessBeforeInstantiation方法");
        return null;
    }
 
    // 接口方法、实例化Bean之后调用
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName)
            throws BeansException {
        System.out
                .println("InstantiationAwareBeanPostProcessor调用postProcessAfterInitialization方法");
        return bean;
    }
 
    // 接口方法、设置某个属性时调用
    @Override
    public PropertyValues postProcessPropertyValues(PropertyValues pvs,
            PropertyDescriptor[] pds, Object bean, String beanName)
            throws BeansException {
        System.out
                .println("InstantiationAwareBeanPostProcessor调用postProcessPropertyValues方法");
        return pvs;
    }
}

　　这个有3个方法，其中第二个方法postProcessAfterInitialization就是重写了BeanPostProcessor的方法。第三个方法postProcessPropertyValues用来操作属性，返回值也应该是PropertyValues对象。

4、演示工厂后处理器接口方法，如下：

package springBeanTest;
 
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 
public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
 
    public MyBeanFactoryPostProcessor() {
        super();
        System.out.println("这是BeanFactoryPostProcessor实现类构造器！！");
    }
 
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory arg0)
            throws BeansException {
        System.out
                .println("BeanFactoryPostProcessor调用postProcessBeanFactory方法");
        BeanDefinition bd = arg0.getBeanDefinition("person");
        bd.getPropertyValues().addPropertyValue("phone", "110");
    }
 
}

　　5、配置文件如下beans.xml，很简单，使用ApplicationContext,处理器不用手动注册：

<?xml version="1.0" encoding="UTF-8"?>
 
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="
            http://www.springframework.org/schema/beans 
            http://www.springframework.org/schema/beans/spring-beans-3.2.xsd">
 
    <bean id="beanPostProcessor" class="springBeanTest.MyBeanPostProcessor">
    </bean>
 
    <bean id="instantiationAwareBeanPostProcessor" class="springBeanTest.MyInstantiationAwareBeanPostProcessor">
    </bean>
 
    <bean id="beanFactoryPostProcessor" class="springBeanTest.MyBeanFactoryPostProcessor">
    </bean>
     
    <bean id="person" class="springBeanTest.Person" init-method="myInit"
        destroy-method="myDestory" scope="singleton" p:name="张三" p:address="广州"
        p:phone="15900000000" />
 
</beans>

　　6、下面测试一下：

package springBeanTest;
 
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
 
public class BeanLifeCycle {
 
    public static void main(String[] args) {
 
        System.out.println("现在开始初始化容器");
 
        ApplicationContext factory = new ClassPathXmlApplicationContext("springBeanTest/beans.xml");
        System.out.println("容器初始化成功");
        //得到Preson，并使用
        Person person = factory.getBean("person",Person.class);
        System.out.println(person);
 
        System.out.println("现在开始关闭容器！");
        ((ClassPathXmlApplicationContext)factory).registerShutdownHook();
    }
}

关闭容器使用的是实际是AbstractApplicationContext的钩子方法。

我们来看一下结果：

现在开始初始化容器
2014-5-18 15:46:20 org.springframework.context.support.AbstractApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@19a0c7c: startup date [Sun May 18 15:46:20 CST 2014]; root of context hierarchy
2014-5-18 15:46:20 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [springBeanTest/beans.xml]
这是BeanFactoryPostProcessor实现类构造器！！
BeanFactoryPostProcessor调用postProcessBeanFactory方法
这是BeanPostProcessor实现类构造器！！
这是InstantiationAwareBeanPostProcessorAdapter实现类构造器！！
2014-5-18 15:46:20 org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
信息: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@9934d4: defining beans [beanPostProcessor,instantiationAwareBeanPostProcessor,beanFactoryPostProcessor,person]; root of factory hierarchy
InstantiationAwareBeanPostProcessor调用postProcessBeforeInstantiation方法
【构造器】调用Person的构造器实例化
InstantiationAwareBeanPostProcessor调用postProcessPropertyValues方法
【注入属性】注入属性address
【注入属性】注入属性name
【注入属性】注入属性phone
【BeanNameAware接口】调用BeanNameAware.setBeanName()
【BeanFactoryAware接口】调用BeanFactoryAware.setBeanFactory()
BeanPostProcessor接口方法postProcessBeforeInitialization对属性进行更改！
【InitializingBean接口】调用InitializingBean.afterPropertiesSet()
【init-method】调用<bean>的init-method属性指定的初始化方法
BeanPostProcessor接口方法postProcessAfterInitialization对属性进行更改！
InstantiationAwareBeanPostProcessor调用postProcessAfterInitialization方法
容器初始化成功
Person [address=广州, name=张三, phone=110]
现在开始关闭容器！
【DiposibleBean接口】调用DiposibleBean.destory()
【destroy-method】调用<bean>的destroy-method属性指定的初始化方法