覆盖在上下文中的父上下文中定义的bean [英] Overriding the bean defined in parent context in a child context

问题描述

我们的应用程序需要支持多租户。每个登机客户可能潜在地覆盖在核心平台级别定义的一个或多个bean或一些bean的属性（通用代码/定义）。我想知道什么是最好的方法来解决这个问题。

Our app has a requirement to support multi-tenancy. Each of the boarded customer might potentially override 1 or more beans or some properties of a bean defined at the core platform level (common code/definitions). I am wondering what is the best way to handle this.

推荐答案

Spring允许你多次重新定义相同的bean名称，将给定名称处理的最后一个bean定义为获胜的bean定义。因此，例如，您可以有一个XML文件来定义您的核心bean，并将其导入到客户端特定的XML文件中，这也重新定义了一些这些bean。但是有一点是脆弱的，因为没有任何机制来专门说这个bean定义是一个覆盖。

Spring allows you to redefine the same bean name multiple times, and takes the last bean definition processed for a given name to be the one that wins. So for example, your could have an XML file defining your core beans, and import that in a client-specific XML file, which also redefines some of those beans. It's a bit fragile, though, since there's no mechanism to specifically say "this bean definition is an override".

我发现最简单的方法是使用新的<$在Spring 3中引入的c $ c> @Bean -syntax 。您可以使用Java定义它们，而不是将bean定义为XML。因此，您的核心bean将在一个 @Bean -annotated类中定义，您的客户端配置将对其进行子类化，并覆盖相应的bean。这允许您使用标准java @Override 注释，明确指出给定的bean定义被覆盖。

I've found that the cleanest way to handle this is using the new @Bean-syntax introduced in Spring 3. Rather than defining beans as XML, you define them in Java. So your core beans would be defined in one @Bean-annotated class, and your client configs would subclass that, and override the appropriate beans. This allows you to use standard java @Override annotations, explicitly indicating that a given bean definition is being overridden.

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