[英]Spring — inject 2 beans of same type
I like constructor-based injection as it allows me to make injected fields final
. 我喜欢基于构造函数的注入,因为它允许我
final
注入字段。 I also like annotation driven injection as it simplifies my context.xml
. 我也喜欢注释驱动注入,因为它简化了我的
context.xml
。 I can mark my constructor with @Autowired
and everything works fine, as long as I don't have two parameters of the same type. 我可以用
@Autowired
标记我的构造函数,一切正常,只要我没有两个相同类型的参数。 For example, I have a class: 例如,我有一个班级:
@Component
public class SomeClass {
@Autowired(required=true)
public SomeClass(OtherClass bean1, OtherClass bean2) {
…
}
}
and an application context with: 和应用程序上下文:
<bean id="bean1" class="OtherClass" />
<bean id="bean2" class="OtherClass" />
There should be a way to specify the bean ID on the constructor of the class SomeClass
, but I can't find it in the documentation. 应该有一种方法在类
SomeClass
的构造函数上指定bean ID,但我在文档中找不到它。 Is it possible, or am I dreaming of a solution that does not exist yet? 是可能,还是我梦想着一个不存在的解决方案呢?
@Autowired
is by-type (in this case); @Autowired
是按类型(在这种情况下); use @Qualifier
to autowire by-name, following the example from spring docs : 使用
@Qualifier
按名称自动装配,遵循spring docs中的示例:
public SomeClass(
@Qualifier("bean1") OtherClass bean1,
@Qualifier("bean2") OtherClass bean2) {
...
}
Note: In contrast to @Autowired which is applicable to fields, constructors and multi-argument methods (allowing for narrowing through qualifier annotations at the parameter level), @Resource is only supported for fields and bean property setter methods with a single argument.
注意:与@Autowired相比,它适用于字段,构造函数和多参数方法(允许在参数级别通过限定符注释缩小),@ Resource仅支持具有单个参数的字段和bean属性setter方法。 As a consequence, stick with qualifiers if your injection target is a constructor or a multi-argument method.
因此,如果您的注射目标是构造函数或多参数方法,请坚持使用限定符。
(below that text is the full example) (在该文本下面是完整示例)
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