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

文章目录

   1.InitializingBean

   2.DisposableBean

   3.案例演示

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