春天的范围差异
在Spring范围中，如果我使用singleton，它在执行逻辑之前加载配置文件时初始化所有的bean。 但是如果我使用原型作为范围，那么这个bean会根据这个调用进行初始化。我对吗？ 单身人士是否像实例变量一样工作为静态和原型？
MainJava.java：
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class MainJava {
public static void main(String arg[]){
AbstractApplicationContext applicationContext=new ClassPathXmlApplicationContext("Beans.xml");
HelloWorld helloWorld=(HelloWorld) applicationContext.getBean("helloworld");
applicationContext.registerShutdownHook();
System.out.println(helloWorld.getMessage());
System.out.println("_________________________");
HelloWorld helloindia=(HelloWorld) applicationContext.getBean("helloindia");
System.out.println(helloindia.getMessage());
helloindia.setMessage("hello vishwa,thisa Bharat");
System.out.println(helloindia.getMessage());
System.out.println("_________________________");
HelloWorld hellonation=(HelloWorld) applicationContext.getBean("helloindia");
System.out.println(hellonation.getMessage());
}
}
HelloWorld.java：
public class HelloWorld {
private String message;
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
public void init(){
System.out.println("initializing bean");
}
public void destroy(){
System.out.println("destroying bean");
}
}
InitHelloWorld.java：
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
public class InitHelloWord implements BeanPostProcessor{
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
System.out.println("after initalizing the bean "+beanName);
return bean;
}
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
System.out.println("before initalizing the bean "+beanName);
return bean;
}
}
Beans.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-3.0.xsd">
<bean name="helloworld" class="com.vishwa.bhat.HelloWorld" init- method="init" destroy-method="destroy">
<property name="message" value="hi vishwa,welcome to this world"> </property>
</bean>
<bean name="helloindia" class="com.vishwa.bhat.HelloWorld" scope="prototype" init-method="init" destroy-method="destroy">
<property name="message" value="hi vishwa,welcome to India"></property>
</bean>
<bean class="com.vishwa.bhat.InitHelloWord"/>
</beans>
如果范围是singleton，则输出：
before initalizing the bean helloworld
initializing bean
after initalizing the bean helloworld
before initalizing the bean helloindia
initializing bean
after initalizing the bean helloindia
hi vishwa,welcome to this world
_________________________
hi vishwa,welcome to India
hello vishwa,thisa Bharat
_________________________
hello vishwa,thisa Bharat
destroying bean
destroying bean
范围原型输出：
before initalizing the bean helloworld
initializing bean
after initalizing the bean helloworld
hi vishwa,welcome to this world
_________________________
before initalizing the bean helloindia
initializing bean
after initalizing the bean helloindia
hi vishwa,welcome to India
hello vishwa,thisa Bharat
_________________________
before initalizing the bean helloindia
initializing bean
after initalizing the bean helloindia
hi vishwa,welcome to India
destroying bean
ApplicationContext在默认情况下以earger模式加载单例。
ApplicationContext实现的默认行为是在启动时急切地预先实例化所有的singleton bean。 预实例化意味着一个ApplicationContext会急切地创建和配置所有的单例bean作为其初始化过程的一部分。 一般来说，这是一件好事，因为这意味着配置或周围环境中的任何错误都会立即被发现（相对于可能的几小时甚至几天）。
如果你需要重新定义你的单例的默认行为，只需指定lazy-init="true"