Spring Bean的生命周期函数

首先：InstantiationAwareBeanPostProcessor接口的postProcessAfterInstantiation方法返回的是false和本文走的不是一样的步骤，结果如何可以根据我提供的代码自行尝试

上图是一个大概的流程，接下来做具体解释： 1.实现了BeanFactoryPostProcessor的类实例化 2.调用BeanFactoryPostProcessor的postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)方法 这里可以得到beanFactory，(GenericBeanDefinition)beanFactory.getBeanDefinition(“studentService”); 它可以得到类的定义 3.实现了BeanPostProcessor的类实例化 4.实现了InstantiationAwareBeanPostProcessor的类实例化

以上四步只会执行一次，下面的几步对于每个需要实例化的bean都会执行

5.调用InstantiationAwareBeanPostProcessor中的 postProcessBeforeInstantiation(Class<?> beanClass, String beanName)方法 该方法可以获得正准备实例化的类的beanName和该bean的Class 6.实例化bean的类（调用构造方法），此时已经有实例化的对象了，只不过没有填充属性值 7.调用InstantiationAwareBeanPostProcessor中的 postProcessAfterInstantiation(Object bean, String beanName)方法 该方法可以刚刚已经实例化过的类的实例（bean）和beanName（默认是类的首字母小写），该方法返回一个boolean值，如果为 true的话走8 8.调用InstantiationAwareBeanPostProcessor中的 public PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName) 和上面的7作用差不多，多了PropertyValues pvs，它里面包含三个属性，还不知道干什么的 propertyValueList = {ArrayList@1596} size = 0 processedProperties = null converted = false 9.装配属性（@Autowired的属性），如果对应的类没有被实例化，走一波它的生命周期（没有销毁） 10.如果正在实例化的这个类实现了BeanNameAware接口，执行它的setBeanName方法，因为在类内部，所以可以通过this得到实例化 的对象，因为走了9，所以得到的实际上已经是实例化完全的bean了，不过bean的生命周期还没走完 11.如果正在实例化的这个类实现了BeanFactoryAware接口，执行它的setBeanFactory(BeanFactory beanFactory)方法， 得到的beanFactory可以使用getBean(String beanName)获得其他实例化好的bean 12.调用BeanPostProcessor中的 postProcessBeforeInitialization(Object bean, String beanName)方法 你可以通过beanName.equals(“你想要的bean名字”)来得到对应实例化的对象bean 13.如果正在实例化的这个类实现了InitializingBean接口，执行它的afterPropertiesSet()方法，也可以用this。。。 14. 用法和12差不多

此时bean除了销毁，已经走过了它大部分的生命周期，可以在主线程中通过getBean方法获得bean了

15.如果bean的类实现了DisposableBean接口并且上下文调用了close()方法，执行重写的destroy()方法，最后销毁。

ps：使用xml配置的bean的init-method，destory-method对应方法和实现InitializingBean，DisposableBean接口 重写它们的afterPropertiesSet()，destroy()方法效果一样，不用写多余的东西。 下面是测试程序所涉及的代码 配置类：

package com.cui.config; import com.cui.model.Student; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; /** * @ClassName Config * @Description * @Author Senwei Cui * @Date 2019/9/23 0023 下午 3:37 * @Version */ @Configuration @ComponentScan("com.cui") public class Config { public Config(){ System.out.println("Config 实例化"); } @Bean public Student student(){ Student student = new Student(); student.setAge(20); student.setName("cui"); return student; } }

模型

package com.cui.model; /** * @ClassName Student * @Description * @Author Senwei Cui * @Date 2019/9/23 0023 下午 3:36 * @Version */ public class Student{ private String name; private Integer age; public Student(){ System.out.println("student 实例化"); } public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } @Override public String toString() { return "Student{" + "name='" + name + '\'' + ", age=" + age + '}'; } }

三个不同后置处理器的实现类

package com.cui.post_processor; import org.springframework.beans.BeansException; import org.springframework.beans.factory.config.BeanFactoryPostProcessor; import org.springframework.beans.factory.config.ConfigurableListableBeanFactory; import org.springframework.beans.factory.support.GenericBeanDefinition; import org.springframework.stereotype.Component; /** * @ClassName CuiBeanFactoryPostProcessor * @Description * @Author Senwei Cui * @Date 2019/9/23 0023 下午 8:56 * @Version */ @Component public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor { public MyBeanFactoryPostProcessor(){ System.out.println("BeanFactoryPostProcessor 实例化"); } @Override public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { GenericBeanDefinition beanDefinition = (GenericBeanDefinition)beanFactory.getBeanDefinition("studentService"); System.out.println("BeanFactoryPostProcessor--postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)"); } } package com.cui.post_processor; import com.cui.sercice.StudentService; import org.springframework.beans.BeansException; import org.springframework.beans.factory.config.BeanPostProcessor; import org.springframework.stereotype.Component; /** * @ClassName StudentServiceBeanPostProcessor * @Description * @Author Senwei Cui * @Date 2019/10/1 0001 下午 3:29 * @Version */ @Component public class MyBeanPostProcessor implements BeanPostProcessor{ public MyBeanPostProcessor(){ System.out.println("BeanPostProcessor 实例化"); } @Override public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { System.out.println(beanName+" before BeanPostProcessor"+bean); if (beanName.equals("studentService")) { ((StudentService)bean).setA(2); } return null; } @Override public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { System.out.println(beanName+" after BeanPostProcessor"+bean); if (beanName.equals("studentService")) { ((StudentService)bean).setA(3); } return null; } } package com.cui.post_processor; import com.cui.sercice.StudentService; import org.springframework.beans.BeansException; import org.springframework.beans.PropertyValues; import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessor; import org.springframework.stereotype.Component; /** * @ClassName myInstantiationAwareBeanPostProcessor * @Description * @Author Senwei Cui * @Date 2019/10/1 0001 下午 4:02 * @Version */ @Component public class MyInstantiationAwareBeanPostProcessor implements InstantiationAwareBeanPostProcessor { public MyInstantiationAwareBeanPostProcessor(){ System.out.println("InstantiationAwareBeanPostProcessor 实例化"); } @Override public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException { System.out.println(beanName+" before InstantiationAwareBeanPostProcessor "); return null; } @Override public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException { System.out.println(beanName+" after InstantiationAwareBeanPostProcessor "+bean); if(beanName.equals("studentService")){ ((StudentService)bean).setB("b"); } //返回false不走postProcessProperties方法 return true; } @Override public PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName) throws BeansException { System.out.println(beanName+" postProcess Properties "+bean); return null; } }

实现了其他生命周期接口的bean的类

package com.cui.sercice; import com.cui.model.Student; import org.springframework.beans.BeansException; import org.springframework.beans.factory.*; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; /** * @ClassName StudentService * @Description * @Author Senwei Cui * @Date 2019/9/23 0023 下午 4:45 * @Version */ @Component public class StudentService implements BeanNameAware , BeanFactoryAware , InitializingBean , DisposableBean { private Integer a; private String b; @Autowired private Student student; public StudentService(){ System.out.println("StudentService 实例化"); } public Integer getA() { return a; } public void setA(Integer a) { this.a = a; } public String getB() { return b; } public void setB(String b) { this.b = b; } public Student getStudent() { return student; } public void setStudent(Student student) { this.student = student; } @Override public String toString() { return "StudentService{" + "a=" + a + ", b='" + b + '\'' + ", student=" + student + '}'; } @Override public void setBeanName(String name) { System.out.println(name+" BeanNameAware--setBeanName this->"+this); } @Override public void setBeanFactory(BeanFactory beanFactory) throws BeansException { Object student = beanFactory.getBean("student"); System.out.println("BeanFactoryAware--setBeanFactory beanFactory.getBean(\"student\");->"+student); } @Override public void afterPropertiesSet() throws Exception { System.out.println("InitializingBean--afterPropertiesSet() "+this); } @Override public void destroy() throws Exception { System.out.println("DisposableBean--destroy() "+this); } }

测试类

```java package com.cui; import com.cui.config.Config; import com.cui.sercice.StudentService; import org.springframework.context.annotation.AnnotationConfigApplicationContext; /** * @ClassName Test1 * @Description * @Author Senwei Cui * @Date 2019/9/23 0023 下午 3:31 * @Version */ public class Test1 { public static void main(String[] args) { //初始化spring上下文，或者说初始话spring容器 AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Config.class); System.out.println("初始化上下文结束"); StudentService studentService = context.getBean(StudentService.class); Integer a = studentService.getA(); System.out.println(a); context.close(); } }

测试结果截图