@Value 將靜態變量設置為 null

Question

我的常量文件：

 @Component
    public class Constants {
        public static String ROOT_DOMAIN;
        @Value("${setting.rootDomain}")
        private void setRootDomain(String rootDomain) {
            ROOT_DOMAIN = rootDomain;
        }
    ...
    }

我的settings.properties：

setting.rootDomain=example.com

我的推薦課程和方法：

@Component
public class MyServiceClass
{
        public void doSomething()
        {
           System.out.println("Root is:" + Constants.ROOT_DOMAIN);
        }
}

但根域即將為空

[更新] 我的 spring-master.xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:util="http://www.springframework.org/schema/util"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd">

    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <list>
                <value>classpath*:/META-INF/spring/local/settings.properties</value>
                <value>classpath*:/META-INF/spring/${DEPLOY_ENVIRONMENT}/settings.properties</value>                        
            </list>
        </property>

        <property name="ignoreUnresolvablePlaceholders" value="true"/>
        <property name="ignoreResourceNotFound" value="true" />
        <property name="searchSystemEnvironment" value="true" />
        <property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE" />
    </bean>
    <context:component-scan base-package="com.myapp.app">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller" />
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Repository"/>  
    </context:component-scan>
    <context:component-scan base-package="com.myapp.app.dao.api" />

    <!-- Application Context Provider -->
    <bean id="appContextProvider" class="com.myapp.app.ApplicationContextProvider"/>

</beans>

ApplicationContextProvider 類如下：

@Component
public class ApplicationContextProvider implements ApplicationContextAware {

     private static ApplicationContext context;

     public static ApplicationContext getApplicationContext() {
         return context;
     }

     @Override
     public void setApplicationContext(ApplicationContext ctx) {
         context = ctx;
     }
}

所以是的，文件在類路徑中

Answer 1

@Value() 在 bean 的初始化時被調用，bean 在不需要在啟動時被初始化，所以除非 bean 被初始化，否則你將沒有該值

Answer 2

我通過將@DependsOn注釋添加到我的 annatated @Bean解決了這個問題，如此@Bean描述的 SpringBoot 中的配置順序