SpringBean的配置详解

• Bean的配置范围
  • 默认情况下（基本的Spring环境），单纯Spring环境Bean的作用范围有两个：Singleton和prototype
  • singleton:单例，默认值，Spring容器创建的时候，就会进行Bean的实例化，并储存到Bean的内部的单例池中，每次getBean时都是从单例池中获取相同的Bean实例
  • prototype：原型，Spring容器初始化时不会创建Bena实例，当调用getBean时才会实例化Bean，每次getBean都会创建一个新的Bean实例。
• 当scope=singleton时

  •     <bean id="userService" class="com.example.Service.Impl.UserServiceImpl" scope="singleton">
    

  •         ApplicationContext context = new ClassPathXmlApplicationContext("application.xml");Object userService1 = context.getBean("userService");Object userService2 = context.getBean("userService");Object userService3 = context.getBean("userService");System.out.println(userService1);System.out.println(userService2);System.out.println(userService3);

  • 运行结果如下：

    • 
       

• 当scope=prototype时

  •     <bean id="userService" name="aaa,bbb" class="com.example.Service.Impl.UserServiceImpl" scope="prototype">
    

  •         ApplicationContext context = new ClassPathXmlApplicationContext("application.xml");Object userService1 = context.getBean("userService");Object userService2 = context.getBean("userService");Object userService3 = context.getBean("userService");System.out.println(userService1);System.out.println(userService2);System.out.println(userService3);

  • 运行结果

    • 

PS：如果添加了SpringWebMVC依赖，scope的值就有多个

        <dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>5.3.7</version></dependency>