目录
1.原理
2.单例多例理论
3.单例多例的代码
1.原理
案例1：
package com.xbb.baenLife;
public class Demo1 {
public static void main(String[] args) {
person p = new person();
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(String name, int age, String sex) {
super();
this.name = name;
this.age = age;
this.sex = sex;
}
@Override
public String toString() {
return "person [name=" + name + ", age=" + age + ", sex=" + sex + "]";
}
public person() {
this.init();
this.name = "bb";
this.age = 18;
this.sex = "哈哈";
}
private void init() {
}
}
效果：
小总结：
1.通过三种方式将（配置文件，注解，配置类）bean标签转成beandifinition对象
2.BeanFactoryPostProcessor旅游在初始化之前修改属性值
3.BeanFactory进行bean实例化，就是生产javabean
4.Aware感知接口，能够拿到spring上下文内部的资源对象
5.BeanPostProcessor后置处理器，相对于环绕通知
2.单例多例理论
创建了四个不同的对象
四个相同的对象：
package com.xbb.baenLife;
public class Demo1 {
public static void main(String[] args) {
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;
}
}
效果：
spring单例模式的优点：
3.单例多例的代码
单例与多例的区别：
scope="prototype"
总结: spring默认采用单例模式
区别：
单例模式下JAVAbean的生命周期
容器生对象生，容器死对象死
多例模式下JAVAbean的生命周期
使用时对象生，死亡跟jvm垃圾回收机制走
bean的初始化时间点，除了与bean管理模式（单例和多例）有关，还跟BeanFactory的子类有关
全部代码：
Demo2：
package com.xbb.baenLife;
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;
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");
InstanceFactory p1 = (InstanceFactory) applicationContext.getBean("InstanceFactory");
InstanceFactory p2 = (InstanceFactory) applicationContext.getBean("InstanceFactory");
// 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");
}
}
InstanceFactory：
package com.xbb.baenLife;
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.xbb.baenLife;
import java.util.List;
public class ParamAction {
private int age;
private String name;
private List hobby;
private int num = 1;
// private UserBiz userBiz = new UserBizImpl1();
public ParamAction() {
super();
}
public ParamAction(int age, String name, List 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);
}
}
配置：
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