Spring(三)--Bean生命周期

基本概念

在Spring中，可以從兩個(gè)層面定義Bean的生命周期，第一個(gè)層面是Bean的作用范圍；第二個(gè)層面是實(shí)例化Bean時(shí)所經(jīng)歷的一系列階段。

BeanFactory中Bean的生命周期

1.生命周期過程圖解

生命周期圖解

假設(shè)一個(gè)Bean實(shí)現(xiàn)了所有的接口，大的概況一下Bean的生命周期：

1.實(shí)例化BeanFactoryPostProcessor：處理的對(duì)象是BeanFactory級(jí)別

2.實(shí)例化BeanPostProcessor實(shí)現(xiàn)類

3.實(shí)例化InstantiationAwareBeanPostProcessorAdapter實(shí)現(xiàn)類，注：該類是BeanPostProcessor的擴(kuò)展

4.執(zhí)行InstantiationAwareBeanPostProcessorAdapter類的postProcessBeforeInstantiation方法

5.Bean的構(gòu)造方法

6.執(zhí)行InstantiationAwareBeanPostProcessorAdapter類的postProcessPropertyValues

7.為Bean注入屬性，即依賴注入

8.調(diào)用BeanNameAware的setBeanName方法

9.調(diào)用BeanNameAware的setBeanFactory方法

10.執(zhí)行BeanPostProcessor的后置處理器，postProcessAfterInitialization方法

11.調(diào)用InitializingBean的afterPropertiesSet方法

12.調(diào)用bean的init-method初始化方法

13.執(zhí)行BeanPostProcessor的postProcessAfterInitialization

14.執(zhí)行InstantiationAwareBeanPostProcessorAdapter的后置方法，postProcessAfterInitialization

15.Bean的使用

16.調(diào)用DiposibleBean的destory方法

17.調(diào)用bean指定的destory-method方法

用代碼驗(yàn)證測(cè)試

測(cè)試Bean - StudentBean類：

/**
 * 測(cè)試生命周期的Bean
 */
public class StudentBean implements InitializingBean, DisposableBean, BeanNameAware, BeanFactoryAware {
    private String name;
    private int age;
 
    private String beanName;         //實(shí)現(xiàn)了BeanNameAware接口，Spring可以將BeanName注入該屬性中
    private BeanFactory beanFactory; //實(shí)現(xiàn)了BeanFactory接口，Spring可將BeanFactory注入該屬性中
 
 
    public StudentBean(){
        System.out.println("【Bean構(gòu)造方法】學(xué)生類的無參構(gòu)造方法");
    }
 
    @Override
    public String toString() {
        return "StudentBean{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", beanName='" + beanName + '\'' +
                '}';
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        System.out.println("【set注入】注入學(xué)生的name屬性");
        this.name = name;
    }
 
    public int getAge() {
        return age;
    }
 
    public void setAge(int age) {
        System.out.println("【set注入】注入學(xué)生的age屬性");
        this.age = age;
    }
 
    /**
     * 自己編寫的初始化方法
     */
    public void myInit(){
        System.out.println("【init-method】調(diào)用init-method屬性配置的初始化方法");
    }
 
    /**
     * 自己編寫的銷毀方法
     */
    public void myDestroy(){
        System.out.println("【destroy-method】調(diào)用destroy-method屬性配置的銷毀方法");
    }
 
    /**
     * BeanFactoryAware接口的方法
     * @param beanFactory
     * @throws BeansException
     */
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        this.beanFactory = beanFactory;
        System.out.println("【BeanFactoryAware接口】調(diào)用BeanFactoryAware的setBeanFactory方法得到beanFactory引用");
    }
 
    /**
     * BeanNameAware接口的方法
     * @param name
     */
    public void setBeanName(String name) {
        this.beanName = name;
        System.out.println("【BeanNameAware接口】調(diào)用BeanNameAware的setBeanName方法得到Bean的名稱");
    }
 
    /**
     * InitializingBean接口的方法
     * @throws Exception
     */
    public void afterPropertiesSet() throws Exception {
        System.out.println("【InitializingBean接口】調(diào)用InitializingBean接口的afterPropertiesSet方法");
    }
 
    /**
     * DisposableBean接口的方法
     * @throws Exception
     */
    public void destroy() throws Exception {
        System.out.println("【DisposableBean接口】調(diào)用DisposableBean接口的destroy方法");
    }
}

MyBeanFactoryPostProcessor工廠處理器類：

public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
 
    public MyBeanFactoryPostProcessor() {
        System.out.println("【BeanFactoryPostProcessor接口】調(diào)用BeanFactoryPostProcessor實(shí)現(xiàn)類構(gòu)造方法");
    }
 
    /**
     * 重寫B(tài)eanFactoryPostProcessor接口的postProcessBeanFactory方法，可通過該方法對(duì)beanFactory進(jìn)行設(shè)置
     */
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
            throws BeansException {
        System.out.println("【BeanFactoryPostProcessor接口】調(diào)用BeanFactoryPostProcessor接口的postProcessBeanFactory方法");
    }
}

MyInstantiationAwareBeanPostProcessor類：

/**
 * 一般情況下，當(dāng)我們需要實(shí)現(xiàn)InstantiationAwareBeanPostProcessor接口時(shí)，是通過繼承Spring框架中InstantiationAwareBeanPostProcessor接口實(shí)現(xiàn)類
 * InstantiationAwareBeanPostProcessorAdapter這個(gè)適配器類來簡化我們實(shí)現(xiàn)接口的工作
 */
public class MyInstantiationAwareBeanPostProcessor extends InstantiationAwareBeanPostProcessorAdapter {
 
    public MyInstantiationAwareBeanPostProcessor() {
        System.out.println("【InstantiationAwareBeanPostProcessor接口】調(diào)用InstantiationAwareBeanPostProcessor構(gòu)造方法");
    }
 
    /**
     * 實(shí)例化Bean之前調(diào)用
    */
    public Object postProcessBeforeInstantiation(Class beanClass, String beanName) throws BeansException {
        System.out.println("【InstantiationAwareBeanPostProcessor接口】調(diào)用InstantiationAwareBeanPostProcessor接口的postProcessBeforeInstantiation方法");
        return null;
    }
 
    /**
     * 實(shí)例化Bean之后調(diào)用
     */
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("【InstantiationAwareBeanPostProcessor接口】調(diào)用InstantiationAwareBeanPostProcessor接口的postProcessAfterInitialization方法");
        return bean;
    }
 
    /**
     * 設(shè)置某個(gè)屬性時(shí)調(diào)用
     */
    public PropertyValues postProcessPropertyValues(PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName)
            throws BeansException {
        System.out.println("【InstantiationAwareBeanPostProcessor接口】調(diào)用InstantiationAwareBeanPostProcessor接口的postProcessPropertyValues方法");
        return pvs;
    }
}

MyBeanPostProcessor類：

public class MyBeanPostProcessor implements BeanPostProcessor {
 
    public MyBeanPostProcessor(){
        System.out.println("【BeanPostProcessor接口】調(diào)用BeanPostProcessor的構(gòu)造方法");
    }
 
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("【BeanPostProcessor接口】調(diào)用postProcessBeforeInitialization方法，這里可對(duì)"+beanName+"的屬性進(jìn)行更改。");
        return bean;
    }
 
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("【BeanPostProcessor接口】調(diào)用postProcessAfterInitialization方法，這里可對(duì)"+beanName+"的屬性進(jìn)行更改。");
        return bean;
    }
}

XML配置：

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
       xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="
            http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans-3.2.xsd">
    
    <!-- 生命周期測(cè)試  -->
    <!--配置Bean的后置處理器-->
    <bean id="beanPostProcessor" class="com.my.spring.life.MyBeanPostProcessor">
    </bean>
 
    <!--配置instantiationAwareBeanPostProcessor-->
    <bean id="instantiationAwareBeanPostProcessor" class="com.my.spring.life.MyInstantiationAwareBeanPostProcessor">
    </bean>
 
    <!--配置BeanFactory的后置處理器-->
    <bean id="beanFactoryPostProcessor" class="com.my.spring.life.MyBeanFactoryPostProcessor">
    </bean>
 
    <bean id="studentBean" class="com.my.spring.life.StudentBean" init-method="myInit"
          destroy-method="myDestroy" scope="singleton">
        <property name="name" value="yanxiao"></property>
        <property name="age" value="21"></property>
    </bean>
</beans>

測(cè)試類：

public class TestCyclelife {
 
    /*
     */
    public static void main(String[] args){
        System.out.println("--------------【初始化容器】---------------");
 
        ApplicationContext context = new ClassPathXmlApplicationContext("Springlife.xml");
        System.out.println("-------------------【容器初始化成功】------------------");
        //得到studentBean，并顯示其信息
        StudentBean studentBean = context.getBean("studentBean",StudentBean.class);
        System.out.println(studentBean);
 
        System.out.println("--------------------【銷毀容器】----------------------");
        ((ClassPathXmlApplicationContext)context).registerShutdownHook();
    }
}

測(cè)試結(jié)果如下：

結(jié)果

轉(zhuǎn)載自:https://blog.csdn.net/weixin_40834464/article/details/82829999

最后編輯于 ：
?著作權(quán)歸作者所有,轉(zhuǎn)載或內(nèi)容合作請(qǐng)聯(lián)系作者
【社區(qū)內(nèi)容提示】社區(qū)部分內(nèi)容疑似由AI輔助生成，瀏覽時(shí)請(qǐng)結(jié)合常識(shí)與多方信息審慎甄別。
平臺(tái)聲明：文章內(nèi)容（如有圖片或視頻亦包括在內(nèi)）由作者上傳并發(fā)布，文章內(nèi)容僅代表作者本人觀點(diǎn)，簡書系信息發(fā)布平臺(tái)，僅提供信息存儲(chǔ)服務(wù)。

相關(guān)閱讀更多精彩內(nèi)容

友情鏈接更多精彩內(nèi)容