Spring默认的情况下,在容器创建的时候会创建JavaBean的对象,
当开启懒加载之后将在使用的时候创建JavaBean的对象
比如对于一个User类通过Spring创建对象
public class User {
public User() {
System.out.println("创建user对象");
}
}
<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 id="user" class="com.wl.spring.User">bean>
beans>
七月 08, 2019 9:16:28 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@300ffa5d: startup date [Mon Jul 08 21:16:28 CST 2019]; root of context hierarchy
七月 08, 2019 9:16:28 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [applicationContext.xml]
创建user对象
结果
七月 08, 2019 9:16:28 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@300ffa5d: startup date [Mon Jul 08 21:16:28 CST 2019]; root of context hierarchy
七月 08, 2019 9:16:28 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [applicationContext.xml]
创建user对象
<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"
default-lazy-init="true"
>
<bean id="user" class="com.wl.spring.User" >bean>
beans>
<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 id="user" class="com.wl.spring.User" lazy-init="true">bean>
beans>
注意:当全局懒加载和每个Bean设置懒加载都存在遵从就近原则
public class StartSpring {
public static void main(String[] args) {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
}
}
运行之后没有除了日志信息,没有结果输出
使用user对象
public class StartSpring {
public static void main(String[] args) {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
User bean = (User) context.getBean("user");
}
}
结果输出
七月 08, 2019 9:36:31 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@300ffa5d: startup date [Mon Jul 08 21:36:31 CST 2019]; root of context hierarchy
七月 08, 2019 9:36:31 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [applicationContext.xml]
创建user对象