【Spring】- Bean生命週期

Spring Bean的生命週期：

1. bean對象實例化
2. 屬性注入
3. beanfactory
4. ApplicationContext
5. postProcessBeforeInitialization
6. InitializingBean
7. postProcessAfterInitialization
8. DisposableBean(銷燬Bean)

Bean生命週期相關接口介紹：

• BeanNameAware: Bean可獲取在BeanFactory中的名稱
• BeanFactoryAware：Bean可獲取所在的BeanFactory對象
• ApplicationContextAware：可獲取Bean所在的ApplicationContext
• InitializingBean:Bean屬性設置完成後的自定義操做接口：例如設置自定義的初始化方法init-method
• DisposableBean：銷燬Bean的相關資源

---

Spring配置文件： 配置簡單的Bean和1個Bean後置處理器，而且設置自定義的初始化方法：init-method="defineInitMethod"

<bean id="concreteBean"  
class="com.zhiwei.lifecycle.ConcreteBean" 
init-method="defineInitMethod"  >
    <property name="name" value="squirrel"/>
</bean>

<bean  class="com.zhiwei.lifecycle.BeanPostProcessorCase"/>

Bean對象,實現相關生命週期接口：

package com.zhiwei.lifecycle;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.BeanNameAware;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

public class ConcreteBean implements BeanNameAware,BeanFactoryAware,
ApplicationContextAware,InitializingBean,DisposableBean{

	private String name;
	
	public ConcreteBean() {
		System.err.println("ConcreteBean實例對象被建立.......");
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		System.err.println("ConcreteBean實例對象默認name屬性注入.........");
		this.name = name;
	}

	/**
	 * BeanNameAware:獲取Bean在BeanFactory的名稱：id
	 */
	@Override
	public void setBeanName(String name) {
		System.err.println("BeanNameAware:ConcreteBean實例對象在BeanFactory的名稱:"+name);
	}

	/**
	 * BeanFactoryAware:獲取Bean所在的Beanfactory
	 */
	@Override
	public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
		boolean flag = beanFactory.containsBean("concreteBean");  //使用BeanFactory的方法判斷Bean是否存在
		System.err.println("BeanfactoryAware:BeanFactory是否存在concreteBean定義："+flag);
	}

	/**
	 * ApplicationContextAware:獲取Bean實例所在的高級BeanFactory容器：ApplicationContext
	 */
	@Override
	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
		boolean flag = applicationContext.containsBean("concreteBean");
		System.err.println("ApplicationContextAware:ApplicationContext是否存在concreteBean定義："+flag);
	}

	/**
	 * InitializingBean:Bean屬性設置完成以後的自定義初始化工做
	 */
	@Override
	public void afterPropertiesSet() throws Exception {
		System.err.println("ConcreteBean完成屬性設置，正在進行初始化........");
	}

	/**
	 * DisposableBean:銷燬Bean相關的資源:destroy-method屬性
	 */
	@Override
	public void destroy() throws Exception {
		 System.err.println("IOC容器正在銷燬Bean資源........");
	}
	
	/**
	 * 自定義初始化方法：init-method屬性
	 */
	public void defineInitMethod(){
		System.err.println("Bean正在自定義初始化......");
	}
}

Bean後置處理器：

package com.zhiwei.lifecycle;
import java.util.Date;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
/**
 * BeanPostProcessor:後置處理器(針對全部的Bean實例) 做用：Bean徹底實例化以前能夠修改Bean的屬性
 */
public class BeanPostProcessorCase implements BeanPostProcessor {

	/**
	 * Bean初始化以前被調用
	 */
	public Object postProcessBeforeInitialization(Object object, String id) throws BeansException {

		System.err.println("正在進行" + object + "實例初始化:,id =" + id + ",時間:" + new Date());
		return object;
	};

	/**
	 * Bean初始化以後被調用
	 */
	@Override
	public Object postProcessAfterInitialization(Object object, String id) throws BeansException {
		System.err.println("已經完成" + object + "實例初始化:,id =" + id + ",時間:" + new Date());
		return object;
	}
}

測試類：

package com.zhiwei.lifecycle;
import org.springframework.context.*;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainTest {

	public static void main(String[] args) {
		
		ApplicationContext applicationContext=new ClassPathXmlApplicationContext("com/zhiwei/lifecycle/applicationContext.xml");
		ConcreteBean concreteBean=(ConcreteBean) applicationContext.getBean("concreteBean");
		System.out.println(concreteBean.getName());
		
		ConfigurableApplicationContext cac = (ConfigurableApplicationContext) applicationContext;
		cac.close();  //關閉IOC容器
	}
}

控制檯打印日誌：

ConcreteBean實例對象被建立.......
ConcreteBean實例對象默認name屬性注入.........
BeanNameAware:ConcreteBean實例對象在BeanFactory的名稱:concreteBean
BeanfactoryAware:BeanFactory是否存在concreteBean定義：true
ApplicationContextAware:ApplicationContext是否存在concreteBean定義：true
正在進行com.zhiwei.lifecycle.ConcreteBean@6ebc05a6實例初始化:,id =concreteBean,時間:Tue Feb 14 14:50:47 CST 2017
ConcreteBean完成屬性設置，正在進行初始化........
Bean正在自定義初始化......
已經完成com.zhiwei.lifecycle.ConcreteBean@6ebc05a6實例初始化:,id =concreteBean,時間:Tue Feb 14 14:50:47 CST 2017
squirrel
IOC容器正在銷燬Bean資源........