Question
Having this problem both in Spring Boot 1.1.5 and 1.1.6 - I'm loading a classpath resource using an @Value annotation, which works just fine when I run the application from within STS (3.6.0, Windows). However, when I run a mvn package and then try to run the jar, I get FileNotFound exceptions.
The resource, message.txt, is in src/main/resources. I've inspected the jar and verified that it contains the file "message.txt" at the top level (same level as application.properties).
Here's the application:
@Configuration
@ComponentScan
@EnableAutoConfiguration
public class Application implements CommandLineRunner {
private static final Logger logger = Logger.getLogger(Application.class);
@Value("${message.file}")
private Resource messageResource;
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
@Override
public void run(String... arg0) throws Exception {
// both of these work when running as Spring boot app from STS, but
// fail after mvn package, and then running as java -jar
testResource(new ClassPathResource("message.txt"));
testResource(this.messageResource);
}
private void testResource(Resource resource) {
try {
resource.getFile();
logger.debug("Found the resource " + resource.getFilename());
} catch (IOException ex) {
logger.error(ex.toString());
}
}
}
The exception:
c:\Users\glyoder\Documents\workspace-sts-3.5.1.RELEASE\classpath-resource-proble
m\target>java -jar demo-0.0.1-SNAPSHOT.jar
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v1.1.5.RELEASE)
2014-09-16 08:46:34.635 INFO 5976 --- [ main] demo.Application
: Starting Application on 8W59XV1 with PID 5976 (C:\Users\glyo
der\Documents\workspace-sts-3.5.1.RELEASE\classpath-resource-problem\target\demo
-0.0.1-SNAPSHOT.jar started by glyoder in c:\Users\glyoder\Documents\workspace-s
ts-3.5.1.RELEASE\classpath-resource-problem\target)
2014-09-16 08:46:34.640 DEBUG 5976 --- [ main] demo.Application
: Running with Spring Boot v1.1.5.RELEASE, Spring v4.0.6.RELEA
SE
2014-09-16 08:46:34.681 INFO 5976 --- [ main] s.c.a.AnnotationConfigA
pplicationContext : Refreshing org.springframework.context.annotation.Annotation
ConfigApplicationContext@1c77b086: startup date [Tue Sep 16 08:46:34 EDT 2014];
root of context hierarchy
2014-09-16 08:46:35.196 INFO 5976 --- [ main] o.s.j.e.a.AnnotationMBe
anExporter : Registering beans for JMX exposure on startup
2014-09-16 08:46:35.210 ERROR 5976 --- [ main] demo.Application
: java.io.FileNotFoundException: class path resource [message.
txt] cannot be resolved to absolute file path because it does not reside in the
file system: jar:file:/C:/Users/glyoder/Documents/workspace-sts-3.5.1.RELEASE/cl
asspath-resource-problem/target/demo-0.0.1-SNAPSHOT.jar!/message.txt
2014-09-16 08:46:35.211 ERROR 5976 --- [ main] demo.Application
: java.io.FileNotFoundException: class path resource [message.
txt] cannot be resolved to absolute file path because it does not reside in the
file system: jar:file:/C:/Users/glyoder/Documents/workspace-sts-3.5.1.RELEASE/cl
asspath-resource-problem/target/demo-0.0.1-SNAPSHOT.jar!/message.txt
2014-09-16 08:46:35.215 INFO 5976 --- [ main] demo.Application
: Started Application in 0.965 seconds (JVM running for 1.435)
2014-09-16 08:46:35.217 INFO 5976 --- [ Thread-2] s.c.a.AnnotationConfigA
pplicationContext : Closing org.springframework.context.annotation.AnnotationCon
figApplicationContext@1c77b086: startup date [Tue Sep 16 08:46:34 EDT 2014]; roo
t of context hierarchy
2014-09-16 08:46:35.218 INFO 5976 --- [ Thread-2] o.s.j.e.a.AnnotationMBe
anExporter : Unregistering JMX-exposed beans on shutdown
Answer
[resource.getFile()
](https://docs.spring.io/spring/docs/current/javadoc-
api/org/springframework/core/io/Resource.html#getFile--) expects the resource
itself to be available on the file system, i.e. it can't be nested inside a
jar file. This is why it works when you run your application in STS (Spring
Tool Suite) but doesn't work once you've built your application and run it
from the executable jar. Rather than using getFile()
to access the
resource's contents, I'd recommend using
[getInputStream()
](https://docs.spring.io/spring/docs/current/javadoc-
api/org/springframework/core/io/InputStreamSource.html#getInputStream--)
instead. That'll allow you to read the resource's content regardless of where
it's located.