我还没有找到我能够理解的Spring bean的高级定义。我经常在Grails文档和书籍中看到它们,但我认为了解它们是什么将是有益的。那么春豆是什么呢?如何使用它们?它们与依赖注入有关吗?
当前回答
Spring bean只是由Spring容器管理的实例对象,也就是说,它们是由框架创建和连接的,并放入一个“对象袋”(容器)中,您以后可以从那里获取它们。
“连接”部分是依赖注入的全部内容,它的意思是你可以说“我将需要这个东西”,框架将遵循一些规则来为你获得适当的实例。
对于那些不习惯Spring的人来说,我认为Wikipedia Spring的文章有一个很好的描述:
Central to the Spring Framework is its inversion of control container, which provides a consistent means of configuring and managing Java objects using reflection. The container is responsible for managing object lifecycles of specific objects: creating these objects, calling their initialization methods, and configuring these objects by wiring them together. Objects created by the container are also called managed objects or beans. The container can be configured by loading XML files or detecting specific Java annotations on configuration classes. These data sources contain the bean definitions which provide the information required to create the beans. Objects can be obtained by means of either dependency lookup or dependency injection. Dependency lookup is a pattern where a caller asks the container object for an object with a specific name or of a specific type. Dependency injection is a pattern where the container passes objects by name to other objects, via either constructors, properties, or factory methods.
其他回答
Spring bean只是由Spring容器管理的实例对象,也就是说,它们是由框架创建和连接的,并放入一个“对象袋”(容器)中,您以后可以从那里获取它们。
“连接”部分是依赖注入的全部内容,它的意思是你可以说“我将需要这个东西”,框架将遵循一些规则来为你获得适当的实例。
对于那些不习惯Spring的人来说,我认为Wikipedia Spring的文章有一个很好的描述:
Central to the Spring Framework is its inversion of control container, which provides a consistent means of configuring and managing Java objects using reflection. The container is responsible for managing object lifecycles of specific objects: creating these objects, calling their initialization methods, and configuring these objects by wiring them together. Objects created by the container are also called managed objects or beans. The container can be configured by loading XML files or detecting specific Java annotations on configuration classes. These data sources contain the bean definitions which provide the information required to create the beans. Objects can be obtained by means of either dependency lookup or dependency injection. Dependency lookup is a pattern where a caller asks the container object for an object with a specific name or of a specific type. Dependency injection is a pattern where the container passes objects by name to other objects, via either constructors, properties, or factory methods.
在Spring中,那些构成应用程序主干并由Spring IoC管理的对象 容器被称为bean。bean只是一个实例化、组装等的对象 由Spring IoC容器管理;
就Spring引导应用程序而言,bean只是一个Java对象,它是在应用程序启动时由Spring框架创建的。
对象的用途可以是任何东西——配置、服务、数据库连接工厂等等——Spring并不关心这些。
大多数bean依赖于其他bean才能工作,例如实体管理器可能需要一个数据库连接。Spring框架能够找出如何将bean自动连接在一起。从应用程序开发人员的角度来看,您只需声明所需的bean,它们就会“神奇地”出现在您的应用程序中,随时可以使用。
春天有IoC容器,里面装着一袋豆子;创建、维护和删除是Spring Container的职责。 我们可以通过布线和自动布线将bean放到Spring中。 “连线”意味着我们手动将其配置到XML文件中,“自动连线”意味着我们将注释放入Java文件中,然后Spring自动扫描Java配置文件所在的根上下文,将其制作并放入Spring的包中。
这里是详细的URI,您可以从中获得有关bean的更多信息
For a Java class to be usable as a Java bean, its setter- and getter-method names need to be as per the JavaBean guidelines (also called design patterns) for properties. If such a Java class is instantiable & manageable by the Spring IoC container, it is a Spring bean. To achieve this, the programmer wires the class as a bean definition of a suitable scope by using XML config files or annotations or a mix of both. The programmer can create new Spring beans out of existing Spring beans by wiring further by passing the latter to constructor-arguments of the former either as string-names as <idref> elements or by dependency injection (it can be recursive).
这个答案可以与我的这个SO答案一起阅读,以获得更多的背景信息。
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