注：@PostConstruct和@PreDestroy 標註不屬於 Spring，它是在J2EE庫- common-annotations.jar。
@PostConstruct 和 @PreDestroy
一個 CustomerService Bean使用 @PostConstruct 和 @PreDestroy 註釋
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;
}
@PostConstruct
public void initIt() throws Exception {
System.out.println("Init method after properties are set : " + message);
}
@PreDestroy
public void cleanUp() throws Exception {
System.out.println("Spring Container is destroy! Customer clean up");
}
}
預設情況下，Spring不會意識到@PostConstruct和@PreDestroy註解。要啟用它，要麼註冊“CommonAnnotationBeanPostProcessor”，要麼在bean配置檔案的<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/beans
http://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/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/context
http://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)被呼叫時，訊息屬性設定後 cleanUp() 方法(@PreDestroy)是在context.close()執行後被呼叫;