懒得笔记3 spring bean 的生存范围 生命周期

 1，生存范围
ScopeDescription

singleton

(Default) 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 HTTP request has 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 an 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.

application

Scopes a single bean definition to the lifecycle of a ServletContext. Only valid in the context of a web-aware Spring ApplicationContext.

 

bean 中scope 的属性 

  1， singleton  单例，默认值  ，不管new 多少次，取到的都是同一个对象。

    

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

2, prototype 原型  每次取到的不一样 struts 里面action 用这个 官方推荐，

2，生命周期

  默认情况下，每次启动都会将所有bean生成放在内存中。

  1,lazy-initialized  (一般不用到）

    context 声明时进行初始化，在get的时候再进行初始化

<bean id="lazy" class="com.foo.ExpensiveToCreateBean" lazy-init="true"/><bean name="not.lazy" class="com.foo.AnotherBean"/>

设置所有的bean 

<beans default-lazy-init="true">    <!-- no beans will be pre-instantiated... --></beans>

2,

init-method destroy-methd 

不要和

prototype

一起用（了解）

 

init-method destroy-methd 

不要和

prototype

一起用（了解）

 

     init-method destroy-methd 不要和prototype一起用（了解）  

     两个属性可以在定义bean在初始化和destroy时调用的方法。