How to avoid platform based NoSuchFileException when using java.nio.file.Paths?

Question

Whenever I run this code locally, the relative path for the file is working just fine but the Kubernetes pod deployment in pre-prod throws NoSuchFileException.

MOCK_DATA_BASE_PATH = "/data/mocks"
private static String getMockDataString(String fileName) {
        try {
            String filePath = MOCK_DATA_BASE_PATH + fileName;
            return Files.lines(Paths.get(filePath))
                    .collect(Collectors.joining(System.lineSeparator()));
        } catch (IOException e) {
            logger.error("Unable to read file {} with reason {}", fileName, e.getMessage());
        }
        return null;
}

When I checked what my local returns for Path projectRoot = Paths.get("").toAbsolutePath(); it returned a local machine specific absolute path like so:/Users/username/path/to/project/mavenModule while the Kubernetes deployment is plainly showing /. Given such difference in both, I'm wondering how I can read the file in both platforms without exception.

The project directory is as such: Project has 3 mvn module1/module2/module2 directories. The files are in path/to/Project/data/mocks/

Real code examples of alternatives would be highly appreciated

You cannot use a Paths and Files to load from t he classpath (that is in the end what you are doing). Use an InputStream for reading like getClass().getResourceAsStream(<your-location>). — M. Deinum
– M. Deinum, Commented Nov 13, 2024 at 8:18
Is this data bundled as part of your application, or is it something else? In the Kubernetes environment, how does it get into the Pod? I'd probably use @M.Deinum's suggestion, moving the data files into moduleN/src/main/resources, and then it the data will be bundled into the jar file and independent of the filesystem path. — David Maze
– David Maze, Commented Nov 13, 2024 at 10:35
There is no point in splitting a file into lines, just to join the lines again afterwards. Simply use Files.readString(…). Unless you really want to replace the platform independent line separators with System.lineSeparator() which is highly doubtful. — Holger
– Holger, Commented Nov 13, 2024 at 12:48
@M.Deinum actually, you can use Path and Files to load from classpath. You just have to use the right filesystem rather than the default filesystem. But, of course, for a single resource, just using getResourceAsStream is simpler. — Holger
– Holger, Commented Nov 13, 2024 at 12:51
Looks like you're concatenating without a file separator character. You should do Path p = Path.of(MOCK_DATA_BASE_PATH, fileName);return Files.readString(p); — g00se
– g00se, Commented Nov 13, 2024 at 12:58

btrballin · Accepted Answer · 2024-11-18 03:53:16Z

0

Based on the comments I managed to make this approach work:

private static String getMockDataString(String fileName) throws MyServiceException {
        String filePath = MOCK_DATA_BASE_PATH + fileName;
    try (InputStream inputStream = MockResponseUtils.class
            .getClassLoader().getResourceAsStream(filePath)) {
        if (inputStream != null) {
            return new String(inputStream.readAllBytes(), StandardCharsets.UTF_8));
        }
    } catch (IOException e) {
        throw new MyServiceException("Unable to load mock data for file " + MOCK_FILENAME);
    }
    return null;
}

edited Nov 18, 2024 at 3:53

answered Nov 13, 2024 at 21:03

btrballin

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1 Comment

g00se Over a year ago

You don't need 3rd party classes. Just return new String(inputStream.readAllBytes(), StandardCharsets.UTF_8));

Shakirov Ramil · Accepted Answer · 2024-11-13 08:20:24Z

-2

You can put MOCK_DATA_BASE_PATH as a variable in your environment

or put to resource directory and filename will be searched in resource

or link like classpath:somedir/file.txt

answered Nov 13, 2024 at 8:20

Shakirov Ramil

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