Bean的作用域：单例与原型

素颜马尾好姑娘i 2023-06-07 05:56 14阅读 0赞

Scope：实体类

package com.student.scope;
    
    public class Scope {
    
    }

bean4.xml ：配置文件（单例）

<?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 id="bean4" class="com.student.scope.Scope" scope="singleton">
    	</bean>
    </beans>

scopeTest：测试类

package com.student.scope;
    
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    import com.student.instance.constructor.Bean1;
    
    public class ScopeTest {
    
    	public static void main(String[] args) {
    		String xmlPath = "com/student/scope/bean4.xml";
    		ApplicationContext applicationContext =new ClassPathXmlApplicationContext(xmlPath);
    		Scope scope1 =(Scope)applicationContext.getBean("bean4");
    		Scope scope2 =(Scope)applicationContext.getBean("bean4");
    		System.out.println(scope1);
    		System.out.println(scope2);
    
    	}
    
    }

输出结果：

十月 13, 2019 5:04:32 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
    信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@46f7f36a: startup date [Sun Oct 13 17:04:32 CST 2019]; root of context hierarchy
    十月 13, 2019 5:04:32 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
    信息: Loading XML bean definitions from class path resource [com/student/scope/bean4.xml]
    com.student.scope.Scope@6a024a67
    com.student.scope.Scope@6a024a67

修改成多例（原型）：

输出结果：

十月 13, 2019 5:10:21 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
    信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@46f7f36a: startup date [Sun Oct 13 17:10:21 CST 2019]; root of context hierarchy
    十月 13, 2019 5:10:21 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
    信息: Loading XML bean definitions from class path resource [com/student/scope/bean4.xml]
    com.student.scope.Scope@32e6e9c3
    com.student.scope.Scope@5056dfcb

总结：1.如果不定义scope属性，系统默认是单例的，也就是同一个实体类，spring容器只能创建同一个实例。  
2.prototype 原型 也叫多例，对于同一个实体类，每次生成的实例（scope1,scope2）都是不同的。