[toc]
bean在定義的時候可以指定范圍,spring提供了6種范圍,其中4種是web應用環境相關的.
| 范圍 | 說明 |
| --- | --- |
|singleton | 默認的,一個bean定義,只有一個對象實例 |
| prototype | 一個bean定義,可以有任意對象實例 |
| request | web環境下,一個bean定義,每次http請求生命周期,對應一個對象實例 |
| session | web環境下,一個bean定義,每次http會話生命周期,對應一個對象實例 |
| application | web環境下,一個bean定義,每次servlet上下文生命周期,對應一個對象實例 |
|websocket |web環境下,一個bean定義,每次websocket請求生命周期,對應一個對象實例 |
## 1.5.1. The singleton scope
單例范圍
spring的單例不同于(Gang of Four (GoF) patterns book)設計模式的單例,設計模式的單例是通過編碼控制一個`ClassLoader`只創建一個類的對象實例.spring的單例則是一個容器一個bean.
xml定義如下
~~~
<bean id="accountService" class="com.foo.DefaultAccountService"/>
<!-- the following is equivalent, though redundant (singleton scope is the default) -->
<bean id="accountService" class="com.foo.DefaultAccountService" scope="singleton"/>
~~~
## 1.5.2. The prototype scope
原型范圍,每次注入其他bean或者調用`getBean()`方法,獲取的都是新的對象實例
一般的規則是,有狀態的bean使用原型范圍,無狀態的bean使用單例范圍
xml定義如下:
~~~
<bean id="accountService" class="com.foo.DefaultAccountService" scope="prototype"/>
~~~
## 1.5.3. Singleton beans with prototype-bean dependencies
如果在單例范圍的bean中注入原型范圍的bean,考慮注入是發生在實例化過程中的,因此,在實例化單例范圍的bean時,也只有一次注入的原型范圍的bean機會,所以,單例bean中的原型,其實是同一個對象,
如果想在單例bean中,每次使用的原型bean都是新的,則參考[method injection](https://docs.spring.io/spring/docs/5.0.7.RELEASE/spring-framework-reference/core.html#beans-factory-method-injection)
## 1.5.4. Request, session, application, and WebSocket scopes
`request, session, application`, and` websocket`這幾個范圍只能在web環境中使用,例如`XmlWebApplicationContext`,如果使用其他非web環境的上下文,如`ClassPathXmlApplicationContext`,則會發生異常`IllegalStateException`
### Initial web configuration
為了能正常使用web環境下的幾個范圍,需要做一些初始化(單例和原型的并不需要),不同的環境有不同的初始化方式
如果是通過spring web mvc訪問bean,請求會經過spring內部的`DispatcherServlet`處理,不再需要其他設置,`DispatcherServlet`已經暴露了所有的相關狀態.
如果使用servlet2.5 web容器,請求會經過spring 外部的`DispatcherServlet`(例如JSF,Struts),需要注冊`org.springframework.web.context.request.RequestContextListener ServletRequestListener`,對于servlet3.0,可以編碼實現`WebApplicationInitializer `接口.其他,或更老的容器,添加下面的聲明到`web.xm`l文件
~~~
<web-app>
...
<listener>
<listener-class>
org.springframework.web.context.request.RequestContextListener
</listener-class>
</listener>
...
</web-app>
~~~
TODO
- 正確打開本書的姿勢
- 第一部分 Core
- 1. Ioc container
- 1.1. Introduction to the Spring IoC container and beans
- 1.2. Container overview
- 1.2.1. Configuration metadata
- 1.2.2. Instantiating a container
- 1.2.3. Using the container
- 1.3. Bean overview
- 1.3.1. Naming beans
- 1.3.2. Instantiating beans
- 1.4. Dependencies
- 1.4.1. Dependency Injection
- 1.4.2. Dependencies and configuration in detail
- 1.4.3. Using depends-on
- 1.4.4. Lazy-initialized beans
- 1.4.5. Autowiring collaborators
- 1.4.6. Method injection
- 1.5 Bean Scopes
- 1.6. Customizing the nature of a bean TODO
- 1.7. Bean definition inheritance TODO
- 1.8. Container Extension Points TODO
- 1.9. Annotation-based container configuration
- 1.9.1. @Required
- 1.9.2. @Autowired
- 1.9.3. Fine-tuning annotation-based autowiring with @Primary
- 1.9.4. Fine-tuning annotation-based autowiring with qualifiers TODO
- 1.9.5. Using generics as autowiring qualifiers TODO
- 1.9.6. CustomAutowireConfigurer TODO
- 1.10. Classpath scanning and managed components
- 1.10.1. @Component and further stereotype annotations
- 1.11. Using JSR 330 Standard Annotations TODO
- 1.12. Java-based container configuration
- 1.12.1. Basic concepts: @Bean and @Configuration
- 1.12.2. Instantiating the Spring container using AnnotationConfigApplicationContext
- 2. Resources
- 2.1. Introduction
- 2.2. The Resource interface
- 2.3. Built-in Resource implementations
- 2.3.1. UrlResource
- 2.3.2. ClassPathResource
- 2.3.3. FileSystemResource
- 2.3.4. ServletContextResource
- 2.3.5. InputStreamResource
- 2.3.6. ByteArrayResource
- 2.4. The ResourceLoader
- 2.5. The ResourceLoaderAware interface
- 2.6. Resources as dependencies
- 2.7. Application contexts and Resource paths
- 2.7.1. Constructing application contexts
- 2.7.2. Wildcards in application context constructor resource paths
- 2.7.3. FileSystemResource caveats
- 3. Validation, Data Binding, and Type Conversion
- 4. Spring Expression Language (SpEL)
- 5. Aspect Oriented Programming with Spring
- 5.1. Introduction
- 5.1.1. AOP concepts
- 5.1.2. Spring AOP capabilities and goals
- 5.1.3. AOP Proxies
- 5.2. @AspectJ support
- 5.2.1. Enabling @AspectJ Support
- 5.2.2. Declaring an aspect
- 5.2.3. Declaring a pointcut
- 5.2.4. Declaring advice
- 5.2.5. Introductions TODO
- 5.2.6. Aspect instantiation models TODO
- 5.2.7. Example
- 5.3. Schema-based AOP support TODO
- 5.4. Choosing which AOP declaration style to use TODO
- 5.5. Mixing aspect types TODO
- 5.6. Proxying mechanisms
- 5.6.1. Understanding AOP proxies
- 5.7. Programmatic creation of @AspectJ Proxies
- 5.8. Using AspectJ with Spring applications
- 5.8.1. Using AspectJ to dependency inject domain objects with Spring
- 5.8.2. Other Spring aspects for AspectJ
- 第二部分 Testing
- 第三部分 Data Access
- 1. Transaction Management
- 1.1. Introduction to Spring Framework transaction management
- 1.2 Advantages of the Spring Framework’s transaction support model
- 1.2.1. Global transactions
- 1.2.2. Local transactions
- 1.2.3. Spring Framework’s consistent programming model
- 1.3. Understanding the Spring Framework transaction abstraction
- 1.4. Synchronizing resources with transactions
- 1.4.1. High-level synchronization approach
- 1.4.2. Low-level synchronization approach
- 1.4.3. TransactionAwareDataSourceProxy
- 1.5. Declarative transaction management
- 1.5.1. Understanding the Spring Framework’s declarative transaction implementation
- 1.5.2. Example of declarative transaction implementation
- 1.5.3. Rolling back a declarative transaction
- 1.5.4. Configuring different transactional semantics for different beans
- 1.5.5. tx:advice元素的 settings
- 1.5.6. Using @Transactional
- 1.5.7. Transaction propagation
- 1.5.8. Advising transactional operations
- 1.5.9. Using @Transactional with AspectJ TODO
- 第四部分 web servlet
- 第五部分 Web Reactive
- 第六部分 Integration
- 第七部分 Languages