Spring Boot: what would be the reasons for a resource file not to be reachable if running from a jar?

Question

I am working on a springboot application. I need to load a file that is in resources. The file can be loaded without issues if I run unit tests (maven, just in case)... or even an integration test. But when I run the application say, for real, from the packaged jar, then it can't be found. I have tried with a couple of different ways to reach it but they fail:

java.lang.IllegalArgumentException: resource path-to-file not found.
        at com.google.common.base.Preconditions.checkArgument(Preconditions.java:217) ~[grpc-1.23.jar!/:?]
        at com.google.common.io.Resources.getResource(Resources.java:195) ~[grpc-1.23.jar!/:?]

Another way:

java.io.FileNotFoundException: class path resource [path-to-file] cannot be resolved to absolute file path because it does not exist
        at org.springframework.util.ResourceUtils.getFile(ResourceUtils.java:177) ~[spring-core-5.1.7.RELEASE.jar!/:5.1.7.RELEASE]

The file is in WEB-INFO/classes/path-to-file which is coming from src/main/resources/path-to-file in my project.

Thanks for any outside-of-the-box ideas.

Update 1 This made it work from jar, and the code is simple enough:

    ClassPathResource cl = new ClassPathResource(resourcePath);
    URL url = cl.getURL();
    String content;
    try (InputStream in = url.openStream()) {
      content = new String(in.readAllBytes(), StandardCharsets.UTF_8);
    }
    LOG.info("Content from {} is {} bytes long", resourcePath, content.length());
    return content;

The tip came from the answer that is marked as accepted. Thanks!

score 1 · Accepted Answer · answered Aug 07 '20 at 14:41

1

May be this would answer your question: Cannot read file within jar file

From my experience, to deal with resource inside jar, i would using InputStream instead

answered Aug 07 '20 at 14:41

Hưng Chu

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Didn't wotk using the URL. Details in the question in update 1 – eftshift0 Aug 07 '20 at 15:08
Actually wait..... didn't repackage. Hold your breath. – eftshift0 Aug 07 '20 at 15:13
You are good! It worked How come I didn't find that answer yesterday? Thanks! – eftshift0 Aug 07 '20 at 15:15
1

you're welcome. I remember faced this once when we were deploying to production LOL – Hưng Chu Aug 07 '20 at 15:31
1

The best of all places to find there is a problem, right? :-D – eftshift0 Aug 07 '20 at 15:32
Not that good, especially the error happens and team lead, PO, Manager is behind your back to watch you fix it – Hưng Chu Aug 07 '20 at 15:34

Spring Boot: what would be the reasons for a resource file not to be reachable if running from a jar?

1 Answers1