04_根据代码浅入spring Bean的生命周期

上一篇说过相关配置的加载，下面开始将bean在spring中的生命周期，本章将先简单的执行代码查看bean的创建过程。

下面是图示：

代码演示：

①配置文件

在这段配置中使用到了set方法 initMethod 和 destroyMethod 创建UserBean
自定义 实现 BeanPostProcessor
<bean name="customBeanPostProcessor" class="com.gl.pojo.CustomBeanPostProcessor"/>
<bean name="user" class="com.gl.pojo.User" init-method="initMethod"  destroy-method="destroyMethod" >
	  <property name="name" value="小明"/>
</bean>

②user类
user 实现 InitializingBean DisposableBean 和自定义 initMethod、destroyMethod

public class User implements InitializingBean, DisposableBean {

	private String name;

	private int age;

	public String getName() {
		return name;
	}

	public void setName(String name) {
		System.out.println("执行setName");
		this.name = name;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	@Override
	public void afterPropertiesSet() throws Exception {
		System.out.println("执行InitializingBean");
	}

	@Override
	public void destroy() throws Exception {
		System.out.println("执行DisposableBean");
	}

	public void initMethod(){
		System.out.println("执行initMethod");
	}

	public void  destroyMethod(){
		System.out.println("执行destroyMethod");
	}

}

③实现BeanPostProcessor

public class CustomBeanPostProcessor implements BeanPostProcessor {

	@Override
	public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
		System.out.println("执行postProcessBeforeInitialization");
		return bean;
	}

	@Override
	public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
		System.out.println("执行postProcessAfterInitialization");
		return bean;
	}
}

④执行获取bean

public class Test {
	public static void main(String[] args) {
		AbstractApplicationContext applicationContext=new ClassPathXmlApplicationContext("spring.xml");
		User user = (User)applicationContext.getBean("user");
		System.out.println(user);
		applicationContext.close();
}

⑤执行结果

执行setName
执行postProcessBeforeInitialization
执行InitializingBean
执行initMethod
执行postProcessAfterInitialization
com.gl.pojo.User@6aa8ceb6
执行DisposableBean
执行destroyMethod

由此代码演示可以看到bean的生命周期的顺序，后续从源码来看bean如何创建的。