How to Configure Class Paths from VM Arguments in Eclipse

When running from Eclipse (STS), "Java Build Path > Library > Class Path External Folder" allows you to read external messages.properties, but is this the question intended to specify when running with the java-jar<spring-boot app > command?

The location of the message source (resource bundle) is specified by spring.massages.basename, where you can also specify a file (base name) on the file system ( file: ).align i18n properties files in spring-boot applications-Stack Overflow).

Property settings can also be specified with command-line arguments (4.2.2.Accessing Command Line Properties).

Therefore, if ./external-resources/messages.properties is the file you want to read,

java-jar<spring-boot app>.jar --spring.messages.basename=file:external-resources/messages

available on the .

Execution sample code , war version

When deploying to Tomcat, Tomcat needs to be directed.Learn more about how to configure:

• Can I create a custom classpath on a per application basis in Tomcat-Stack Overflow
• Apache Tomcat9 Configuration Reference (9.0.34) - The Resources Component

Tomcat9 deploys the aforementioned war and reads the message resources under the /tmp/external-resources directory.

• Move the messages.properties file under the /tmp/external-resources/ directory
• Create a conf/Catalina/localhost/demo-0.0.1-SNAPSHOT.xml file under Tomcat's main body.Includes:

<Context>
  <Resources>
    <PostResources
      className="org.apache.catalina.webresources.DirResourceSet"
      base="/tmp/external-resources"
      webAppMount="/WEB-INF/classes"/>
  </Resources>
</Context>

With this configuration, the /tmp/external-resources directory is inserted into the war file /WEB-INF/classes so that applications can find message resources in the class path.