Java框架spring 學習筆記（四）：BeanPostProcessor接口

若是咱們須要在Spring容器完成Bean的實例化，配置和其餘的初始化先後後添加一些本身的邏輯處理。

編寫InitHelloWorld.java

 1 package com.example.spring;
 2 
 3 import org.springframework.beans.BeansException;
 4 import org.springframework.beans.factory.config.BeanPostProcessor;
 5 
 6 public class InitHelloWorld implements BeanPostProcessor{
 7     //初始化Bean前
 8     @Override
 9     public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
10         System.out.println("Befor Initialization :"+beanName);
11         return bean;
12     }
13 
14     //初始化Bean後
15     @Override
16     public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
17         System.out.println("After Initialization :"+beanName);
18         return bean;
19     }
20 }

 

編寫Beans.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
 5 
 6     <bean id="helloWorld" class="com.example.spring.HelloWorld"
 7           init-method="init" destroy-method="destroy">
 8         <property name="message" value="Hello World"></property>
 9     </bean>
10 
11     <bean class="com.example.spring.InitHelloWorld"></bean>
12 </beans>

 

編寫HelloWorld.java

 1 package com.example.spring;
 2 
 3 public class HelloWorld {
 4     private String message;
 5     public void setMessage(String message){
 6         this.message  = message;
 7     }
 8 
 9     public void getMessage(){
10         System.out.println("Your Message : " + message);
11     }
12     //定義初始化方法
13     public void init(){
14         System.out.println("Bean is going through init.");
15     }
16     //定義銷燬方法
17     public void destroy(){
18         System.out.println("Bean will destroy now.");
19     }
20 }

運行輸出

BeforeInitialization : helloWorld
Bean is going through init.
AfterInitialization : helloWorld
Your Message : Hello World!
Bean will destroy now.

能夠看到初始化bean的先後分別調用了postProcessBeforeInitialization和postProcessAfterInitialization方法