Spring之InitializingBean接口和DisposableBean接口介绍

  本文来介绍下InitializingBean接口和DisposableBean接口的作用

1.InitializingBean

  该接口的作用是：允许一个bean在它的所有必须属性被BeanFactory设置后，来执行初始化的工作，该接口中只有一个方法，afterPropertiesSet

public interface InitializingBean {

	/**
	 * Invoked by the containing {@code BeanFactory} after it has set all bean properties
	 * and satisfied {@link BeanFactoryAware}, {@code ApplicationContextAware} etc.
	 * <p>This method allows the bean instance to perform validation of its overall
	 * configuration and final initialization when all bean properties have been set.
	 * @throws Exception in the event of misconfiguration (such as failure to set an
	 * essential property) or if initialization fails for any other reason
	 */
	void afterPropertiesSet() throws Exception;

}

2.DisposableBean

  该接口的作用是：允许在容器销毁该bean的时候获得一次回调。DisposableBean接口也只规定了一个方法：destroy

public interface DisposableBean {

	/**
	 * Invoked by the containing {@code BeanFactory} on destruction of a bean.
	 * @throws Exception in case of shutdown errors. Exceptions will get logged
	 * but not rethrown to allow other beans to release their resources as well.
	 */
	void destroy() throws Exception;

}

3.案例演示

/**
 * 实现InitializingBean和DisposableBean接口
 * @author dengp
 *
 */
public class User implements InitializingBean,DisposableBean{

	private int id;
	
	private String name;
	
	private String beanName;
	
	public User(){
		System.out.println("User 被实例化");
	}

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

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

	public String getBeanName() {
		return beanName;
	}

	public void setBeanName(String beanName) {
		this.beanName = beanName;
	}
	
	@Override
	public String toString() {
		return "User [id=" + id + ", name=" + name + ", beanName=" + beanName + "]";
	}

	@Override
	public void destroy() throws Exception {
		// TODO Auto-generated method stub
		System.out.println("destory ....");
	}

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

配置文件

<?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">

	<bean class="com.dpb.pojo.User" id="user" >
		<property name="name" value="波波烤鸭"></property>
	</bean>
	
</beans>

测试代码

@Test
public void test1() {
	ClassPathXmlApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
	User user = ac.getBean(User.class);
	System.out.println(user);
	ac.registerShutdownHook();
}

输出结果：

User 被实例化
设置：波波烤鸭
afterPropertiesSet....
User [id=0, name=波波烤鸭, beanName=null]
destory ....

  通过输出能够显示spring初始化bean的时候，如果bean实现了InitializingBean接口，会自动调用afterPropertiesSet方法，在bean被销毁的时候如果实现了DisposableBean接口会自动回调destroy方法后然后再销毁