Spring IOC bean的生存周期scope范围

a)     singleton 单例(默认)

b)     proptotype 每次创建新的对象

Bean scopes

Scope Description

singleton	Scopes a single bean definition to a single object instance per Spring IoC container.
prototype	Scopes a single bean definition to any number of object instances.
request	Scopes a single bean definition to the lifecycle of a single HTTP request; that is each and every HTTP request will have its own instance of a bean created off the back of a single bean definition. Only valid in the context of a web-aware Spring ApplicationContext.
session	Scopes a single bean definition to the lifecycle of a HTTP Session. Only valid in the context of a web-aware Spring ApplicationContext.
global session	Scopes a single bean definition to the lifecycle of a global HTTP Session. Typically only valid when used in a portlet context. Only valid in the context of a web-aware Spring ApplicationContext.

 

request、session、global session 在web中才起效，比如和struts集成

但很少用，struts中可以很方便访问request等

 

<bean id="userService" class="com.service.UserService" scope="prototype">
   <!--
   <property name="userDAO" ref="u" />
    -->
    <constructor-arg>
     <ref bean="u"/>
    </constructor-arg>
  </bean>

 

UserService service = (UserService)ctx.getBean("userService");
UserService service2 = (UserService)ctx.getBean("userService");
  System.out.println(service == service2); //false

 

 如果scope="singleton"，则是单例，为true