Unable to load the configuration application.properties

user_15406157 0
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I'm implementing the piece of code, that make changes in some configuration file. In the very beginning I'm trying to find my application.properties file:

File file = new File(Objects.requireNonNull(this.getClass().getClassLoader().getResource("application.properties")).getFile());

File is located in /opt/pcc/lib/smp-asnef.jar in src/main/resources/application.properties

But I get an error:

Error: Unable to load the configuration from the URL file:/root/file:/opt/pcc/lib/smp-asnef.jar!/BOOT-INF/classes!/application.properties

Can you explain this error (I want to understand where exactly he is looking for a file and what exactly it means)? And what could be a solution?

I'm ready to give additional information if needed.

spring-boot properties java
2 Answers

Resources in the build path are automatically in the classpath of the running Java program. Considering this, you should always load such resources with a class loader. Have a look at this:

String propName = "application.properties"; 
ClassLoader loader = Thread.currentThread().getContextClassLoader();
Properties props = new Properties();
try(InputStream resourceStream = loader.getResourceAsStream(propName)) {
    props.load(resourceStream);
}
// use props here ...

Alternatively you could use this getResourceAsStream() method:

import org.apache.commons.io.IOUtils;

String fileName = "application.properties";
ClassLoader classLoader = getClass().getClassLoader();

try (InputStream inputStream = classLoader.getResourceAsStream(fileName)) {
    String result = IOUtils.toString(inputStream, StandardCharsets.UTF_8);
    System.out.println(result);

} catch (IOException e) {
    e.printStackTrace();
}

Let me know if that helped :)

user_92840960

To read a file from a Java jar file uses the getClass and getResourceAsStream methods. Sample :

    InputStream is = getClass().getClassLoader().getResourceAsStream("some_file");
    InputStreamReader isr = new InputStreamReader(is);
    BufferedReader br = new BufferedReader(isr);
    // some logic
    br.close();
    isr.close();
    is.close();

that make changes in some configuration file.

You can't change any content of a jar which is currently used. Files are considered as "locked". So if you want to modify config I suggest

  • to write this file outside the jar.
  • notify spring by using the spring.config.location cli param
  • choose a way to reload the file on any cnanges - reloading strategy
user_49117750
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