目录
1.2.1、通过三种方式(配置文件、注解、配置类)将bean标签转成beandifinition对象
1.2.2、通过BeanFactoryPostPricessor可以在初始化之前修改属性
1.2.3、BeanFactory进行bean实例化,就是生产javabean
1.2.4、Aware感知接口,能够在拿到Spring上下文中内部的资源对象
1.2.4、BeanPostProcessor后置处理器,相当于环绕通知
1、Bean的初始化过程
1.1、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.xml中的标签转换成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
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 + "]";
}
}
5)beanfactory:bean工厂。它按照我们的要求生产我们需要的各种各样的bean
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
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
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)After
8)destory:销毁
1.2、总结
1.2.1、通过三种方式(配置文件、注解、配置类)将bean标签转成beandiFinition对象
1.2.2、通过beanfactoryPostPricessor可以在初始化之前修改属性
1.2.3、beanfactory进行bean实例化,就是生产javabean
1.2.4、Aware感知接口,能够在拿到Spring上下文中内部的资源对象
1.2.4、BeanPostProcessor后置处理器,相当于环绕通知
2、Bean的单列模式与多列模式
2.1、多列模式
scope="prototype"
案列:
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 + "]";
// }
//
}
运行结果:
2.2、单列模式
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;
}
}
2.2.1、弊端
2.3、体现单列与多列的区别
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");
}
}
②ParamAction
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);
}
}
③Demo2
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 bean的單例多例
*/
public class Demo2 {
// 体现单例与多例的区别
@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,容器销毁对象不一定销毁;
applicationContext.close();
}
// 体现单例与多例的初始化的时间点 instanceFactory
@Test
public void test2() {
ApplicationContext applicationContext = new ClasspathXmlApplicationContext("/spring-context.xml");
}
// beanfactory会初始化bean对象,但会根据不同的实现子类采取不同的初始化方式
// 默认情况下bean的初始化,单例模式立马会执行,但是此时Xmlbeanfactory作为子类,单例模式下容器创建,bean依赖没有初始化,只有要获取使用bean对象才进行初始化
@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");
}
}
运行效果:
原文地址:https://www.jb51.cc/wenti/3285633.html
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