spring容器在初始化Bean时前和后的操作

淩亂°似流年 2022-06-13 02:24 117阅读 0赞

> 在某些情况下，Spring容器在初始化Bean的时候，希望在初始化bean前和销毁bean前进行一些资源的加载和释放的操作。可以通过一下三种方式完成。

*  Bean的方法加上@PostConstruct和@PreDestroy注解
 *  在xml中定义init-method和destory-method方法
 *  Bean实现InitializingBean和DisposableBean接口

### @PostConstruct和@PreDestroy注解 ###

#### JavaBean代码 ####

@Component
    public class PersonService {
        private String message;
    
        public String getMessage() {
            return message;
        }
    
        public void setMessage(String message) {
            this.message = message;
        }
    
        @PostConstruct
        public void init() {
            System.out.println("PersonService.class init method ...");
        }
    
        @PreDestroy
        public void cleanUp() {
            System.out.println("PersonService.class cleanUp method ...");
        }
    }

#### spring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" xmlns:context="http://www.springframework.org/schema/context" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.2.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.2.xsd">
    
        
        <context:component-scan base-package="spring.zhujie" />
    
    </beans>

#### 测试代码和结果 ####

*  测试代码

public static void main(String[] args) {
         AbstractApplicationContext context = new ClassPathXmlApplicationContext("spring-zhujie.xml");
         context.registerShutdownHook();
    }

*  运行结果

PersonService.class init method ...
    PersonService.class cleanUp method ...

### 在XML中定义init-method和destory-method方法 ###

#### JavaBean代码 ####

public class PersonService {
        private String message;
    
        public String getMessage() {
            return message;
        }
    
        public void setMessage(String message) {
            this.message = message;
        }
    
        public void init() {
            System.out.println("PersonService.class init method ...");
        }
    
        public void cleanUp() {
            System.out.println("PersonService.class cleanUp method ...");
        }
    }

#### spring配置文件 ####

#### 测试代码和结果 ####

*  测试代码

public static void main(String[] args) {
            AbstractApplicationContext context = new ClassPathXmlApplicationContext("spring-xml.xml");
            context.registerShutdownHook();
    }

*  运行结果

PersonService.class init method ... 六月 23, 2017 9:42:06 下午 org.springframework.context.support.ClassPathXmlApplicationContext doClose
    信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@7a94c5e7: startup date [Fri Jun 23 21:42:06 CST 2017]; root of context hierarchy
    PersonService.class cleanUp method ...

### Bean实现InitializingBean和DisposableBean接口 ###

#### JavaBean代码 ####

public class PersonService implements InitializingBean, DisposableBean { 
        private String message;
    
        public String getMessage() {
            return message;
        }
    
        public void setMessage(String message) {
            this.message = message;
        }
    
        @Override
        public void afterPropertiesSet() throws Exception {
            System.out.println("PersonService.class init method ...");
        }
    
        @Override
        public void destroy() throws Exception {
            System.out.println("PersonService.class cleanUp method ...");
        }
    }

#### spring配置文件 ####

#### 测试代码和结果 ####

*  测试代码

public static void main(String[] args) {
            AbstractApplicationContext context = new ClassPathXmlApplicationContext("spring-interface.xml");
            context.registerShutdownHook();
        }

*  运行结果

PersonService.class init method ...
    PersonService.class cleanUp method ...