Spring:构造函数注入具有基于注释的配置的原始值(属性) [英] Spring: constructor injection of primitive values (properties) with annotation based configuration

问题描述

我正在尝试在 Spring 3 中使用基于注解的配置来配置一个类，该类将原始值作为其构造函数参数:

I'm trying to configure a class with Annotation based configuration in Spring 3, which takes primitive values as its constructor arguments:

@Component
class MyBean {
  MyBean(String arg1, String arg2) {
    // ...
  }
}

以及这样的应用程序上下文:

And an application context like this:

<beans [...]>
  <context:component-scan base-package="com.example" />
  <context:property-override location="/WEB-INF/example.properties" />
</beans>

我试图找到某种方法来指定构造函数参数应该从属性文件中获取.显然，这确实适用于采用常规 bean 的构造函数(例如 MyClass(Bean bean1, OtherBean bean2))，但仅适用于属性?

I'm trying to find some way to specify that the constructor arguments should be taken from the properties file. Apparently this does work with constructors that take regular beans (e.g. MyClass(Bean bean1, OtherBean bean2)), but just properties?

我还尝试使用 Spring 3 的 @Value 注释和值的 EL 表达式来注释构造函数参数，例如 @Value("#{prop.Prop1}") arg1，但这似乎也不起作用.

I have also tried annotating the constructor arguments with Spring 3's @Value annotation and an EL expression for the value, like @Value("#{prop.Prop1}") arg1, but that doesn't seem to work either.

推荐答案

以下代码适用于 <context:property-placeholder .../>:

@Component 
public class MyBean { 
    @Autowired
    public MyBean(@Value("${prop1}") String arg1, @Value("${prop2}") String arg2) { 
        // ... 
    } 
} 

但是<context:property-override .../>是一个很具体的东西，这里不适合.

But <context:property-override .../> is a very specific thing, it's not suitable here.

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