Spring 框架如何自动装配一个集合 [英] How does Spring framework autowire a collection
问题描述
我从未见过自动装配的集合:
I've never seen an autowired collection:
@Service
public class SomeFactory {
@Autowired
private List<Foo> foos;
@PostConstruct
public void init() {
for(Foo foo: foos) {
//do something
}
}
}
在 init() 方法中,我可以看到 foos 已经有几个条目.我猜 Spring 知道谁应该是 foos 的入口.但是,怎么样?如果我想在 foos 中添加一个 Foo 对象应该怎么做?需要在属性文件中进行配置,还是有其他想法?
In init() method, I can see foos has several entries already. I guess Spring knows who's supposed to be the entry of foos. But, how? What should I do if I want to add a Foo object into foos? Need to configure in a property file, or any other idea?
推荐答案
Spring 的 BeanFactory 基本上是一个 bean 的注册表.这些 bean 可以使用 XML 声明,或者使用配置类中的 @Bean
注释方法,或者使用包扫描自动发现.
Spring's BeanFactory is basically a registry of beans. These beans can be declared using XML, or using @Bean
-annotated methods in a Configuration class, or be automatically discovered using package scanning.
当您请求 List
时,Spring 会找到所有 Foo 类型的 bean,创建一个包含这些 bean 的 List,然后注入该列表.
When you ask for a List<Foo>
, Spring finds all the beans that are of type Foo, creates a List containing those beans, and injects that list.
关于 Autowired 的文档 解释一下,顺便说一句:
The documentation about Autowired explains it, BTW:
还可以通过将注解添加到需要该类型数组的字段或方法来从 ApplicationContext 提供特定类型的所有 bean
It is also possible to provide all beans of a particular type from the ApplicationContext by adding the annotation to a field or method that expects an array of that type
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