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

image

假设一个Bean实现了所有的接口，大的概况一下Bean的生命周期：

1.实例化BeanFactoryPostProcessor：处理的对象是BeanFactory级别

2.实例化BeanPostProcessor实现类

3.实例化InstantiationAwareBeanPostProcessorAdapter实现类，注：该类是BeanPostProcessor的扩展

4.执行InstantiationAwareBeanPostProcessorAdapter类的postProcessBeforeInstantiation方法

5.Bean的构造方法

6.执行InstantiationAwareBeanPostProcessorAdapter类的postProcessPropertyValues

7.为Bean注入属性，即依赖注入

8.调用BeanNameAware的setBeanName方法

9.调用BeanNameAware的setBeanFactory方法

10.执行BeanPostProcessor的后置处理器，postProcessAfterInitialization方法

11.调用InitializingBean的afterPropertiesSet方法

12.调用bean的init-method初始化方法

13.执行BeanPostProcessor的postProcessAfterInitialization

14.执行InstantiationAwareBeanPostProcessorAdapter的后置方法，postProcessAfterInitialization

15.Bean的使用

16.调用DiposibleBean的destory方法

17.调用bean指定的destory-method方法

为了上述流程的正确性，我们可以用代码来测试一下：

测试Bean - StudentBean类：

测试Bean - StudentBean类：

/**

• 测试生命周期的Bean

• Created by kxm
  */
  public class StudentBean implements InitializingBean, DisposableBean, BeanNameAware, BeanFactoryAware {
  private String name;
  private int age;

  private String beanName; //实现了BeanNameAware接口，Spring可以将BeanName注入该属性中
  private BeanFactory beanFactory; //实现了BeanFactory接口，Spring可将BeanFactory注入该属性中

  public StudentBean(){
  System.out.println("【Bean构造方法】学生类的无参构造方法");
  }

  @Override
  public String toString() {
  return "StudentBean{" +
  "name='" + name + ''' +
  ", age=" + age +
  ", beanName='" + beanName + ''' +
  '}';
  }

  public String getName() {
  return name;
  }

  public void setName(String name) {
  System.out.println("【set注入】注入学生的name属性");
  this.name = name;
  }

  public int getAge() {
  return age;
  }

  public void setAge(int age) {
  System.out.println("【set注入】注入学生的age属性");
  this.age = age;
  }

  /**

  • 自己编写的初始化方法
    */
    public void myInit(){
    System.out.println("【init-method】调用init-method属性配置的初始化方法");
    }

  /**

  • 自己编写的销毁方法
    */
    public void myDestroy(){
    System.out.println("【destroy-method】调用destroy-method属性配置的销毁方法");
    }

  /**

  • BeanFactoryAware接口的方法
  • @param beanFactory
  • @throws BeansException
    */
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
    this.beanFactory = beanFactory;
    System.out.println("【BeanFactoryAware接口】调用BeanFactoryAware的setBeanFactory方法得到beanFactory引用");
    }

  /**

  • BeanNameAware接口的方法
  • @param name
    */
    public void setBeanName(String name) {
    this.beanName = name;
    System.out.println("【BeanNameAware接口】调用BeanNameAware的setBeanName方法得到Bean的名称");
    }

  /**

  • InitializingBean接口的方法
  • @throws Exception
    */
    public void afterPropertiesSet() throws Exception {
    System.out.println("【InitializingBean接口】调用InitializingBean接口的afterPropertiesSet方法");
    }

  /**

  • DisposableBean接口的方法
  • @throws Exception
    */
    public void destroy() throws Exception {
    System.out.println("【DisposableBean接口】调用DisposableBean接口的destroy方法");
    }
    }
    MyBeanFactoryPostProcessor工厂处理器类：

public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor {

public MyBeanFactoryPostProcessor() {
    System.out.println("【BeanFactoryPostProcessor接口】调用BeanFactoryPostProcessor实现类构造方法");
}

/**
 * 重写BeanFactoryPostProcessor接口的postProcessBeanFactory方法，可通过该方法对beanFactory进行设置
 */
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
        throws BeansException {
    System.out.println("【BeanFactoryPostProcessor接口】调用BeanFactoryPostProcessor接口的postProcessBeanFactory方法");
}

}
MyInstantiationAwareBeanPostProcessor类：

/**

• 一般情况下，当我们需要实现InstantiationAwareBeanPostProcessor接口时，是通过继承Spring框架中InstantiationAwareBeanPostProcessor接口实现类

• InstantiationAwareBeanPostProcessorAdapter这个适配器类来简化我们实现接口的工作
  */
  public class MyInstantiationAwareBeanPostProcessor extends InstantiationAwareBeanPostProcessorAdapter {

  public MyInstantiationAwareBeanPostProcessor() {
  System.out.println("【InstantiationAwareBeanPostProcessor接口】调用InstantiationAwareBeanPostProcessor构造方法");
  }

  /**

  • 实例化Bean之前调用
    */
    public Object postProcessBeforeInstantiation(Class beanClass, String beanName) throws BeansException {
    System.out.println("【InstantiationAwareBeanPostProcessor接口】调用InstantiationAwareBeanPostProcessor接口的postProcessBeforeInstantiation方法");
    return null;
    }

  /**

  • 实例化Bean之后调用
    */
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
    System.out.println("【InstantiationAwareBeanPostProcessor接口】调用InstantiationAwareBeanPostProcessor接口的postProcessAfterInitialization方法");
    return bean;
    }

  /**

  • 设置某个属性时调用
    */
    public PropertyValues postProcessPropertyValues(PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName)
    throws BeansException {
    System.out.println("【InstantiationAwareBeanPostProcessor接口】调用InstantiationAwareBeanPostProcessor接口的postProcessPropertyValues方法");
    return pvs;
    }
    }
    MyBeanPostProcessor类：

/**

• Created by kxm
  */
  public class MyBeanPostProcessor implements BeanPostProcessor {

  public MyBeanPostProcessor(){
  System.out.println("【BeanPostProcessor接口】调用BeanPostProcessor的构造方法");
  }

  public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
  System.out.println("【BeanPostProcessor接口】调用postProcessBeforeInitialization方法，这里可对"+beanName+"的属性进行更改。");
  return bean;
  }

  public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
  System.out.println("【BeanPostProcessor接口】调用postProcessAfterInitialization方法，这里可对"+beanName+"的属性进行更改。");
  return bean;
  }
  }
  XML配置：

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">

测试类：

public class TestCyclelife {

/**
 * Created by yanxiao on 2016/8/1.
 */
public static void main(String[] args){
    System.out.println("--------------【初始化容器】---------------");

    ApplicationContext context = new ClassPathXmlApplicationContext("Springlife.xml");
    System.out.println("-------------------【容器初始化成功】------------------");
    //得到studentBean，并显示其信息
    StudentBean studentBean = context.getBean("studentBean",StudentBean.class);
    System.out.println(studentBean);

    System.out.println("--------------------【销毁容器】----------------------");
    ((ClassPathXmlApplicationContext)context).registerShutdownHook();
}

}

测试结果如下：

image

符合上述的Bean的生命周期，至此，Bean的生命周期问题已基本解决，不过还等待着你继续去深入。