Spring:具有基于注释的配置的原始值(属性)的构造函数注入

2022-01-13 00:00:00 dependency-injection annotations spring java

我正在尝试在 Spring 3 中使用基于注释的配置来配置一个类，它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) {
    // ...
  }
}

还有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>

我正在尝试找到某种方法来指定构造函数参数应取自属性文件.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))，但只是属性?

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

以下代码在 <context:property-placeholder .../> 下运行良好:

The following code works fine with <context:property-placeholder .../>:

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

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

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

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