在Spring中，既可以實現InitializingBean和DisposableBean接口或在bean配置文件中指定?init-method?和?destroy-method?在初始化和銷毀回調函數。在這篇文章中，我們將介紹如何使用 @PostConstruct 和 @PreDestroy?注解來做同樣的事情。

注：@PostConstruct和@PreDestroy 標注不屬于 Spring，它是在J2EE庫-?common-annotations.jar。

@PostConstruct 和 @PreDestroy

一個 CustomerService?Bean使用 @PostConstruct 和 @PreDestroy 注釋 package com.yiibai.customer.services;import javax.annotation.PostConstruct; import javax.annotation.PreDestroy;public class CustomerService {String message;public String getMessage() {return message;}public void setMessage(String message) {this.message = message;}@PostConstructpublic void initIt() throws Exception {System.out.println("Init method after properties are set : " + message);}@PreDestroypublic void cleanUp() throws Exception {System.out.println("Spring Container is destroy! Customer clean up");}} 默認情況下，Spring不會意識到@PostConstruct和@PreDestroy注解。要啟用它，要么注冊“CommonAnnotationBeanPostProcessor”，要么在bean配置文件的<context:annotation-config?/>‘?指定，

1. CommonAnnotationBeanPostProcessor

<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-2.5.xsd"><bean class="org.springframework.context.annotation.CommonAnnotationBeanPostProcessor" /><bean id="customerService" class="com.yiibai.customer.services.CustomerService"><property name="message" value="i'm property message" /></bean></beans>

2. <context:annotation-config />

<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"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-2.5.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context-2.5.xsd"><context:annotation-config /><bean id="customerService" class="com.yiibai.customer.services.CustomerService"><property name="message" value="i'm property message" /></bean></beans>

執行結果

package com.yiibai.common;import org.springframework.context.ConfigurableApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext;import com.yiibai.customer.services.CustomerService;public class App {public static void main( String[] args ){ConfigurableApplicationContext context = new ClassPathXmlApplicationContext(new String[] {"Spring-Customer.xml"});CustomerService cust = (CustomerService)context.getBean("customerService");System.out.println(cust);context.close();} }

輸出結果

Init method after properties are set : im property message com.yiibai.customer.services.CustomerService@47393f ... INFO: Destroying singletons in org.springframework.beans.factory. support.DefaultListableBeanFactory@77158a: defining beans [customerService]; root of factory hierarchy Spring Container is destroy! Customer clean up initIt()方法(@PostConstruct)被調用時，消息屬性設置后?cleanUp()?方法(@PreDestroy)是在context.close()執行后被調用; 下載源代碼 –?http://pan.baidu.com/s/1qX2W6xI

總結

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