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Bean life cycle
2022-08-09 23:12:00 【Price pit pit】
目录
四、BeanThe singleton and multi-instance patterns
一、bean的生命周期
Servlet的生命周期：
初始化：init ——>Tomcat启动,Servlet对象就创建/初始化了
服务：service——>浏览器发送请求,对应的ServletMake a processing call
销毁：destroy——>Tomcat停止
SpringIs the management of all in the projectJavabean对象;
这些是Javabean对象什么时候生,What time is the service available,什么时候销毁er一、Bean的初始化过程
二,ean的初始化过程
Spring Bean的生命周期
1）通过XML、Java annotation（注解）以及Java Configuration（配置类）等方式加载Spring Bean
2）BeanDefinitionReader：解析Bean的定义.在Spring容器启动过程中,会将Bean解析成Spring内部的BeanDefinition结构;理解为：将spring.xmlThe labels in are converted to BeanDefinition结构,有点类似于XML解析
3）BeanDefinition：包含了很多属性和方法.例如：id、class（类名）、
scope、ref（依赖的bean）等等.其实就是将bean（例如）的定义信息,存储到这个对应BeanDefinition相应的属性中例如：
-----> BeanDefinition(id/class/scope)4）BeanFactoryPostProcessor：是Spring容器功能的扩展接口.
注意：
1）BeanFactoryPostProcessor在spring容器加载完BeanDefinition之后,
在bean实例化之前执行的
2）对bean元数据（BeanDefinition）进行加工处理,也就是BeanDefinition
属性填充、修改等操作
三,案例
package com.zking.beanLife;
public class Demo1 {
public static void main(String[] args) {
Person p=new Person();
p.setSex("男");
System.out.println(p.getSex());
}
}
class Person{
private String name;
private int age;
private String sex;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public Person() {
this.init();
this.name="zs";
this.age=20;
this.sex="未知";
}
public void init() {
}
@Override
public String toString() {
return "Person [name=" + name + ", age=" + age + ", sex=" + sex + "]";
}
}
运行结果：
案例：
BeanFactory -> List<BeanDefinition>
BeanDefinition(id/class/scope/init-method)
<bean class="com.zking.spring02.biz.BookBizImpl"/>
foreach(BeanDefinition bean : List<BeanDefinition>){
//根据class属性反射机制实例化对象
//反射赋值设置属性
}
6）Aware感知接口：在实际开发中,经常需要用到Spring容器本身的功能资源
例如：BeanNameAware、ApplicationContextAware等等
BeanDefinition 实现了 BeanNameAware、ApplicationContextAware
如图：
7）BeanPostProcessor：后置处理器.在Bean对象实例化和引入注入完毕后,
在显示调用初始化方法的前后添加自定义的逻辑.（类似于AOP的绕环通知）
前提条件：如果检测到Bean对象实现了BeanPostProcessor后置处理器才会执行
案例：
package com.zking.beanLife;
public class Demo1 {
public static void main(String[] args) {
Person p=new Person();
p.setSex("男");
System.out.println(p.getSex());
}
}
class Person{
private String name;
private int age;
private String sex;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public Person() {
this.init();
this.name="zs";
this.age=20;
this.sex="未知";
}
public void init() {
}
@Override
public String toString() {
return "Person [name=" + name + ", age=" + age + ", sex=" + sex + "]";
}
}
Before和After方法
BeanPostProcessor
1）Before
2）调用初始化Bean（InitializingBean和init-method,Bean的初始化才算完成）
3）After8）destory：销毁
2、总结
①通过三种方式(配置文件、注解、配置类)将bean标签转成beandifinition对象
②通过BeanFactoryPostPricessorProperties can be modified before initialization
③BeanFactory进行bean实例化,就是生产javabean
④Aware感知接口,able to getSpringThe resource object inside the context
⑤BeanPostProcessor后置处理器,相当于环绕通知
四、BeanThe singleton and multi-instance patterns
1、多例模式
scope="prototype"
案例：
package com.zking.beanLife;
public class Demo1 {
public static void main(String[] args) {
Person p1=new Person();
Person p2=new Person();
Person p3=new Person();
Person p4=new Person();
System.out.println(p1);
System.out.println(p2);
System.out.println(p3);
System.out.println(p4);
}
}
class Person{
private String name;
private int age;
private String sex;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public Person() {
this.init();
this.name="zs";
this.age=20;
this.sex="未知";
}
public void init() {
}
// @Override
// public String toString() {
// return "Person [name=" + name + ", age=" + age + ", sex=" + sex + "]";
// }
//
}
运行截图：
2、单例模式
scope="singLeton"
案例：
package com.zking.beanLife;
public class Demo1 {
public static void main(String[] args) {
// Person p1=new Person();
// Person p2=new Person();
// Person p3=new Person();
// Person p4=new Person();
Person p1=Person.newInstance();
Person p2=Person.newInstance();
Person p3=Person.newInstance();
Person p4=Person.newInstance();
System.out.println(p1);
System.out.println(p2);
System.out.println(p3);
System.out.println(p4);
}
}
class Person{
private Person() {
}
private final static Person p=new Person();
public static Person newInstance() {
return p;
}
}
3、Demonstrate the difference between singleton and multiple instances
①InstanceFactory
package com.zking.beanLife;
public class InstanceFactory {
public void init() {
System.out.println("初始化方法");
}
public void destroy() {
System.out.println("销毁方法");
}
public void service() {
System.out.println("业务方法");
}
}
ParamAction
package com.zking.beanLife;
import java.util.List;
public class ParamAction {
private int age;
private String name;
private List<String> hobby;
private int num = 1;
// private UserBiz userBiz = new UserBizImpl1();
public ParamAction() {
super();
}
public ParamAction(int age, String name, List<String> hobby) {
super();
this.age = age;
this.name = name;
this.hobby = hobby;
}
public void execute() {
// userBiz.upload();
// userBiz = new UserBizImpl2();
System.out.println("this.num=" + this.num++);
System.out.println(this.name);
System.out.println(this.age);
System.out.println(this.hobby);
}
}
Demo2：
package com.zking.beanLife;
import org.junit.Test;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
/*
* spring bean的生命週期
* spring beanA single instance of multiple instances
*/
public class Demo2 {
// Demonstrate the difference between singleton and multiple instances
@Test
public void test1() {
ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("/spring-context.xml");
// ApplicationContext applicationContext = new ClassPathXmlApplicationContext("/spring-context.xml");
ParamAction p1 = (ParamAction) applicationContext.getBean("paramAction");
ParamAction p2 = (ParamAction) applicationContext.getBean("paramAction");
// System.out.println(p1==p2);
p1.execute();
p2.execute();
// 单例时,容器销毁instanceFactory对象也销毁;多例时,The container destroys the object is not necessarily destroyed;
applicationContext.close();
}
// The time point that reflects the initialization of singleton and multiple instances instanceFactory
@Test
public void test2() {
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("/spring-context.xml");
}
// BeanFactory会初始化bean对象,However, different initialization methods will be adopted according to different implementation subclasses
// 默认情况下bean的初始化,The singleton pattern will execute immediately,但是此时XmlBeanFactory作为子类,Container creation in singleton mode,beanDependencies are not initialized,Only to get usedbeanobject is initialized
@Test
public void test3() {
// ClassPathXmlApplicationContext applicationContext = new
// ClassPathXmlApplicationContext("/spring-context.xml");
Resource resource = new ClassPathResource("/spring-context.xml");
BeanFactory beanFactory = new XmlBeanFactory(resource);
// InstanceFactory i1 = (InstanceFactory) beanFactory.getBean("instanceFactory");
}
}
运行结果：
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