Spring Framework 5.2.2 文檔中文翻譯版之IOC容器與Bean簡介

特別說明

這是一個由simviso團隊所組織進行的基於Spring Framework 5.2.2版本基礎文檔翻譯。若是想要深刻討論，可掃描下方二維碼，加入官方羣和知秋的知識星球，免費給你們分享相關知識。

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核心技術（Core Technologies）

This part of the reference documentation covers all the technologies that are absolutely integral to the Spring Framework.

參考文檔的這一部分涵蓋了Spring框架中全部必不可少的技術。

Foremost amongst these is the Spring Framework’s Inversion of Control (IoC) container. A thorough treatment of the Spring Framework’s IoC container is closely followed by comprehensive coverage of Spring’s Aspect-Oriented Programming (AOP) technologies. The Spring Framework has its own AOP framework, which is conceptually easy to understand and which successfully addresses the 80% sweet spot of AOP requirements in Java enterprise programming.

其中最重要的就是Spring框架中的IoC容器。當對Spring IoC容器充分理解後，緊隨其來的就是對Spring AOP（面向切面編程）相關的全面介紹。Spring框架擁有它本身的AOP框架，該框架從概念上易於理解，它成功解決了Java企業編程中80%AOP需求相關痛點。

Coverage of Spring’s integration with AspectJ (currently the richest — in terms of features — and certainly most mature AOP implementation in the Java enterprise space) is also provided.

其中也涵蓋了Spring與AspectJ的集成（就功能而言，目前它是最豐富也是Java企業領域中最成熟的AOP實現）。

IoC容器

This chapter covers Spring’s Inversion of Control (IoC) container.

本章節涵蓋了Spring IoC容器相關內容。

Spring IoC容器與Bean簡介（Introduction to the Spring IoC Container and Beans）

This chapter covers the Spring Framework implementation of the Inversion of Control (IoC) principle. IoC is also known as dependency injection (DI). It is a process whereby objects define their dependencies (that is, the other objects they work with) only through constructor arguments, arguments to a factory method, or properties that are set on the object instance after it is constructed or returned from a factory method. The container then injects those dependencies when it creates the bean. This process is fundamentally the inverse (hence the name, Inversion of Control) of the bean itself controlling the instantiation or location of its dependencies by using direct construction of classes or a mechanism such as the Service Locator pattern.

本章節涵蓋了Spring框架對於控制反轉(IoC)原理的實現。IoC也被稱爲依賴注入(DI) 。在此過程當中，對象只能經過構造函數參數，工廠方法的參數來定義其依賴項（即與之一塊兒使用的其餘對象），或者在經過構造器構造或從工廠方法返回獲得對象實例以後，在對象實例上對其屬性進行設置。而後，容器在建立bean時注入那些依賴項。此過程從本質上來說是經過使用類的直接構造或者例如服務定位模式之類的機制，從根本上反轉了bean自身對它依賴項的定位（知秋注：和其餘bean創建依賴聯繫）或實例化（所以稱爲控制反轉）。

The org.springframework.beans and org.springframework.context packages are the basis for Spring Framework’s IoC container. The BeanFactory

interface provides an advanced configuration mechanism capable of managing any type of object. ApplicationContext is a sub-interface of BeanFactory. It adds:

• Easier integration with Spring’s AOP features
• Message resource handling (for use in internationalization)
• Event publication
• Application-layer specific contexts such as the WebApplicationContext for use in web applications.

org.springframework.beans 和 org.springframework.context 兩個包是Spring框架中IoC容器的基礎。BeanFactory 接口提供了一種可以管理任何類型對象的高級配置機制。ApplicationContext 是 BeanFactory 的子接口，它添加了如下特性：

• 更易於與Spring AOP特性相整合
• 消息資源處理（用於國際化處理）
• 事件發佈
• 應用層特定上下文，例如：在Web應用中所使用的 WebApplicationContext

In short, the BeanFactory provides the configuration framework and basic functionality, and the ApplicationContext adds more enterprise-specific functionality. The ApplicationContext is a complete superset of the BeanFactory and is used exclusively in this chapter in descriptions of Spring’s IoC container. For more information on using the BeanFactory instead of the ApplicationContext, see [beans-beanfactory].

簡單來講，BeanFactory 提供了配置框架以及基礎功能，而 ApplicationContext 添加了更多企業特定的功能。ApplicationContext 是 BeanFactory 的一個完整超集，它在本章中只用來描述Spring IoC容器。若是想了解更多 BeanFactory 使用上的信息而不是 ApplicationContext 的話，請查看 [beans-beanfactory] 這一章節。

In Spring, the objects that form the backbone of your application and that are managed by the Spring IoC container are called beans. A bean is an object that is instantiated, assembled, and otherwise managed by a Spring IoC container. Otherwise, a bean is simply one of many objects in your application. Beans, and the dependencies among them, are reflected in the configuration metadata used by a container.

在Spring中，構成你應用程序主幹並經過Spring IoC容器進行管理的對象被稱爲bean。bean是一個由Spring IoC容器實例化，組裝並管理的一個對象。不然的話，bean只是你應用中衆多對象中的一個而已。Bean及其之間的依賴關係都反映在容器使用的配置元數據中。