How to Access Resources from JAR Files in Java?

Loading Resources from JAR Files

In your application, you're loading resources using WinProcessor.class.getResource("repository").toString(), which provides a file path when running from an IDE but returns a JAR URL when executing as a JAR file. This discrepancy arises because JAR files contain resources in a compressed and packaged format.

Understanding Resource Loading in JARs

When you package your application into a JAR file, its contents, including resources, are stored within the archive. When you attempt to access a resource from within a JAR file, the JVM treats it differently than a file in the file system. The getResource method returns a URL that points to the resource's location within the JAR.

Solution: Using getResourceAsStream

To resolve this issue, it's recommended to use getResourceAsStream instead of getResource. getResourceAsStream returns an InputStream that allows you to read the resource's contents directly from the JAR file. You can then use the InputStream to create the necessary objects, such as a ConfigurationContext or set system properties.

Here's an updated example using getResourceAsStream:

InputStream repositoryInputStream = WinProcessor.class.getResourceAsStream("repository");
ConfigurationContext ctx = (ConfigurationContext) ConfigurationContextFactory.createConfigurationContextFromFileSystem(repositoryInputStream, null);

InputStream fileNameInputStream = WinProcessor.class.getResourceAsStream("file_name");
System.setProperty("javax.net.ssl.trustStore", fileNameString);

By using getResourceAsStream, you can avoid the issue of path differences between running from an IDE and executing as a JAR file. The InputStream correctly points to the resource's location within the JAR, allowing you to access its contents.

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