@Controller 类中的 Spring @Value 注释不评估属性文件中的值 [英] Spring @Value annotation in @Controller class not evaluating to value inside properties file

问题描述

我是 Spring 的新手，并尝试使用 @Value("${loginpage.message}") 注释注入一个带有值的字符串，该注释位于用 @ 注释的控制器内Controller 注释和我的字符串的值被评估为字符串 "${loginpage.message}" 而不是我的属性文件中的内容.

I am new to Spring and trying to inject a string with a value using the @Value("${loginpage.message}") annotation inside of a controller annotated with the @Controller annotation and the value of my string is being evaluated as the string "${loginpage.message}" and not what is inside my properties file.

下面是我的控制器，其中包含我想注入的字符串message".

Below is my controller with the string 'message' that I want to inject.

@Controller
public class LoginController extends BaseController {
    @Value("${loginpage.message}")
    private String message;

    @RequestMapping("/")
    public String goToLoginPage(Model model) {
        model.addAttribute("message", message);

        return "/login";
    }
}

我的应用程序上下文如下所示:

My application context looks like this:

<context:property-placeholder location="classpath:properties/application.properties" />

<context:annotation-config />

<context:component-scan base-package="com.me.application" />

我的属性文件有一行:

loginpage.message=this is a test message

Spring 必须在某个时候获取该值，因为每当我将 @Value("${loginpage.message}") 更改为不在属性文件中的值，例如 @Value("${notInPropertiesFile}")，我得到一个例外.

Spring must be picking up the value at some point because whenever I change @Value("${loginpage.message}") to a value not in the properties file like @Value("${notInPropertiesFile}"), I get an exception.

推荐答案

问题好像已经有人问过了Spring 3.0.5 不从属性评估@Value 注释

It seems that the question has been already asked Spring 3.0.5 doesn't evaluate @Value annotation from properties

Web 应用程序根和 servlet 应用程序上下文之间的差异是 Spring 中最容易混淆的来源之一，请参阅 Spring框架中applicationContext.xml和spring-servlet.xml的区别

The difference between web app root and servlet application contexts is one of the top sources of confusion in Spring, see Difference between applicationContext.xml and spring-servlet.xml in Spring Framework

来自 @Value javadoc:

From @Value javadoc :

注意@Value注解的实际处理是由一个BeanPostProcessor

Note that actual processing of the @Value annotation is performed by a BeanPostProcessor

来自 Spring 文档:

BeanPostProcessor 接口的范围是每个容器的.这仅在您使用容器层次结构时才相关.如果你在一个容器中定义了一个 BeanPostProcessor，它只会在那个容器中的 bean 上工作.在一个容器中定义的 Bean 不会由另一个容器中的 BeanPostProcessor 进行后处理，即使两个容器属于同一层次结构的一部分.

BeanPostProcessor interfaces are scoped per-container. This is only relevant if you are using container hierarchies. If you define a BeanPostProcessor in one container, it will only do its work on the beans in that container. Beans that are defined in one container are not post-processed by a BeanPostProcessor in another container, even if both containers are part of the same hierarchy.

这篇关于@Controller 类中的 Spring @Value 注释不评估属性文件中的值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！