Spring Bean的生命周期管理
一、Spring Bean的生命周期
通过以下方式来指定Bean的初始化和销毁方法，
当Bean为单例时，Bean归Spring容器管理，Spring容器关闭，就会调用Bean的销毁方法
当Bean为多例时，Bean不归Spring容器管理，Spring容器关闭，不会调用Bean的销毁方法
二、通过@Bean的参数（initMethod ,destroyMethod）指定Bean的初始化和销毁方法
1、项目结构
2、Person
public class Person {
public Person(){
System.out.println("Person 创建了...");
}
public void init(){
System.out.println("Person 初始化了...");
}
public void destroy(){
System.out.println("Person 被销毁了...");
}
}
3、Bean注册配置类（单实例）
import com.dashu.bean.Person;
import org.springframework.context.annotation.*;
@Configuration
public class BeanConfig {
@Bean(initMethod = "init",destroyMethod = "destroy")
public Person person(){
return new Person();
}
}
4、测试类
import com.dashu.bean.Person;
import com.dashu.config.BeanConfig;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class Main {
public static void main(String[] args) {
//加载配置类获取容器
AnnotationConfigApplicationContext annotationConfigApplicationContext = new AnnotationConfigApplicationContext(BeanConfig.class);
//获取Bean
Person bean = annotationConfigApplicationContext.getBean(Person.class);
//关闭容器
annotationConfigApplicationContext.close();
}
}
5、测试结果
6、Bean注册配置类（多实例）
import com.dashu.bean.Person;
import org.springframework.context.annotation.*;
@Configuration
public class BeanConfig {
@Scope("prototype")
@Bean(initMethod = "init",destroyMethod = "destroy")
public Person person(){
return new Person();
}
}
7、测试结果
三、Bean实现接口InitializingBean, DisposableBean
1、Person
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
public class Person implements InitializingBean, DisposableBean {
public Person(){
System.out.println("Person 创建了...");
}
@Override
public void afterPropertiesSet() throws Exception {
System.out.println("Person 初始化了...");
}
@Override
public void destroy() throws Exception {
System.out.println("Person 被销毁了...");
}
}
2、Bean注册配置类
import com.dashu.bean.Person;
import org.springframework.context.annotation.*;
@Configuration
public class BeanConfig {
@Bean
public Person person(){
return new Person();
}
}
3、测试结果
四、通过注解@PostConstruct和@PreDestroy
@PostConstruct：标注在Bean的初始化方法上
@PreDestroy：标注在Bean的销毁方法上
1、Person
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
public class Person {
public Person(){
System.out.println("Person 创建了...");
}
@PostConstruct
public void init(){
System.out.println("Person 初始化了...");
}
@PreDestroy
public void destroy(){
System.out.println("Person 被销毁了...");
}
}
2、测试结果
五、使用接口BeanPostProcessor实现类（后置处理器）
1、项目结构
2、Person
import org.springframework.stereotype.Component;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
@Component
public class Person {
public Person(){
System.out.println("Person 创建了...");
}
@PostConstruct
public void init(){
System.out.println("Person 初始化了...");
}
@PreDestroy
public void destroy(){
System.out.println("Person 被销毁了...");
}
}
3、Bean注册配置类
import org.springframework.context.annotation.*;
@Configuration
@ComponentScan({"com.dashu"})
public class BeanConfig {
}
4、BeanPostProcessor实现类（后置处理器）
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessor;
import org.springframework.lang.Nullable;
import org.springframework.stereotype.Component;
@Component
public class MyBeanPostProcessor implements BeanPostProcessor {
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
System.out.println("初始化之前..."+beanName+"=["+bean+"]");
return bean;
}
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
System.out.println("初始化之后..."+beanName+"=["+bean+"]");
return bean;
}
}
5、测试结果
总结
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