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目录
基本概念
singleton作用域就是单例模式；用spring容器实现单例模式
而prototype作用域可以理解为多例模式！
Singleton作用域例子：
左侧的ref就是右侧bean的id，这里就是把右边的bean通过spring注入到左侧的bean中；
而Singleton是如下的情况：
而Prototype是这样的
演示
如下的文件结构：
Bean1.java
package singleandprodemo.demo;
public class Bean1 {
private Bean2 bean2;
public Bean2 getBean2() {
return bean2;
}
public void setBean2(Bean2 bean2) {
this.bean2 = bean2;
}
@Override
public String toString() {
return "Bean1{" +
"bean2=" + bean2 +
'}';
}
}
Bean2.java
package singleandprodemo.demo;
public class Bean2 {
}
spring.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean class="singleandprodemo.demo.Bean2" id="bean2" scope="singleton"/>
<bean class="singleandprodemo.demo.Bean1" id="bean1">
<property name="bean2" ref="bean2"/>
</bean>
</beans>这里要注意bean1没有填写scope，这里没填的默认是scope为singleton
这里编写如下的运行代码：
public void contextLoads() {
ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");
Bean2 bean2_1 = context.getBean("bean2", Bean2.class);
System.out.println("bean2_1 = " + bean2_1);
Bean2 bean2_2 = context.getBean("bean2", Bean2.class);
System.out.println("bean2_2 = " + bean2_2);
Bean1 bean1 = context.getBean("bean1", Bean1.class);
System.out.println("bean1 = " + bean1);
}运行截图如下：
从这里可以知道，单例模式在一个spring上下文环境中，被单例化；
修改如下运行代码：
public void contextLoads() {
ApplicationContext context1 = new ClassPathXmlApplicationContext("spring.xml");
Bean2 bean2_1 = context1.getBean("bean2", Bean2.class);
System.out.println("bean2_1 = " + bean2_1);
Bean2 bean2_2 = context1.getBean("bean2", Bean2.class);
System.out.println("bean2_2 = " + bean2_2);
Bean1 bean1 = context1.getBean("bean1", Bean1.class);
System.out.println("bean1 = " + bean1);
System.out.println("---------------华丽的分割线---------------");
ApplicationContext context2 = new ClassPathXmlApplicationContext("spring.xml");
Bean2 bean2_3 = context2.getBean("bean2", Bean2.class);
System.out.println("bean2_1 = " + bean2_3);
Bean2 bean2_4 = context2.getBean("bean2", Bean2.class);
System.out.println("bean2_2 = " + bean2_4);
Bean1 bean2 = context2.getBean("bean1", Bean1.class);
System.out.println("bean1 = " + bean2);
}运行截图如下：
可见不同的spring上下文环境中实例的Bean是不一样的；
修改spring.xml文件如下：
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean class="singleandprodemo.demo.Bean2" id="bean2" scope="singleton"/>
<bean class="singleandprodemo.demo.Bean1" id="bean1" scope="prototype">
<property name="bean2" ref="bean2"/>
</bean>
</beans>运行代码如下：
public void contextLoads() {
ApplicationContext context1 = new ClassPathXmlApplicationContext("spring.xml");
Bean2 bean2_1 = context1.getBean("bean2", Bean2.class);
System.out.println("bean2_1 = " + bean2_1);
Bean2 bean2_2 = context1.getBean("bean2", Bean2.class);
System.out.println("bean2_2 = " + bean2_2);
Bean1 bean1 = context1.getBean("bean1", Bean1.class);
Bean1 bean11 = context1.getBean("bean1", Bean1.class);
System.out.println("bean1 = " + bean1);
System.out.println("bean11 = " + bean11);
System.out.println(bean1 == bean11);
}运行截图如下：
从这里可以知道，但bean1为prototye的时候，实例化的bean1是不同的，（因为上面的false）
下面给出一张表：
这里如果有这样的一个应用场景：
Bean1是singleton，Bean2是prototype，Bean1依赖Bean2，希望每次调用Bean1的某个方法时，该方法拿到的Bean2都是一个新的实例；
这里使用到了方法注入！！！！！！！！！！！！！！
修改Bean1.java
package singleandprodemo.demo;
public abstract class Bean1 {
protected abstract Bean2 createBean2();
public void printBean2(){
System.out.println("bean2 = " + createBean2());
}
}
spring.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean class="singleandprodemo.demo.Bean2" id="bean2" scope="prototype"/>
<bean class="singleandprodemo.demo.Bean1" id="bean1" scope="prototype">
<!-- <property name="bean2" ref="bean2"/> -->
<lookup-method name="createBean2" bean="bean2"></lookup-method>
</bean>
</beans>测试代码如下：
public void contextLoads() {
ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");
Bean1 bean1 = context.getBean("bean1", Bean1.class);
bean1.printBean2();
bean1.printBean2();
bean1.printBean2();
bean1.printBean2();
}运行截图如下：
