spring-boot项目中如何访问依赖资源属性

Question

Facing issue with dependency variables.

I have some core dependency projects. they have their own properties. now when I use these dependencies in my project, I don't want to define those properties again in my application.properties file. also if I define the same variable in application.properties that will override the dependency properties

for Ex.

DependencyProjectA
    -src/main/java
        -com.myApp.accessor
            ResourceAccessor.java
             {
               @Value("${projectA.value}")
                private String projectValue;
             }
    -src/test/resources
        -projectA.properties
          projectA.value: test123

ProjectB (dependent on ProjectA)
    -src/main/java
        -xyz.java
         {
           @Value("${projectB.value}")
           private String projectValue;

         }
    -src/test/resources
         -application.properties
           projectB.value: test123

    -pom.xml
     <dependency>
      DependencyProjectA
     </dependency>

Now when I run the projectB jar with the command java -jar target/projectB.jar I'm facing the following issue:

Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'projectA.value' in value "${projectA.value}"
        at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:178) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
        at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:124) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
        at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:236) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]

How we can resolve the dependency jar variable with a dependency property file (projectA.properties) instead of defining in projectB property file (application.properties).

Answer 1

If I understood right, your properties files are located in src/main/resources but not in src/test/resources , otherwise test properties files are not packing in final jar file. For Spring Boot 2.4.0 or newer, you can use property spring.config.import

Example:

spring.config.import=classpath:projectA.properties

For older Spring Boot version, I used application argument spring.config.additional-location for running application:

spring.config.additional-location=classpath:projectA.properties

Anyway you can set up PropertySourcesPlaceholderConfigurer

    @Bean
    public static PropertySourcesPlaceholderConfigurer properties() {
        PropertySourcesPlaceholderConfigurer pspc = new PropertySourcesPlaceholderConfigurer();
        Resource[] resources = new ClassPathResource[]{new ClassPathResource("projectA.properties")};
        pspc.setLocations(resources);
        pspc.setIgnoreUnresolvablePlaceholders(true);
        return pspc;
    }

And there are some additional properties to customize the folders from which the custom properties files will be loaded. Please check: https://docs.spring.io/spring-boot/docs/2.1.9.RELEASE/reference/html/boot-features-external-config.html