In Java, JarURLConnection is a class that provides a way to read the contents of a JAR file as if it were a directory structure. It allows you to open a connection to a JAR file, read its contents, and retrieve resources such as classes, images, or configuration files that are contained within it.

Here is an example usage of JarURLConnection to read a file from a JAR file:

import java.io.IOException;
import java.io.InputStream;
import java.net.JarURLConnection;
import java.net.URL;
import java.util.jar.JarEntry;

public class JarURLConnectionExample {
    public static void main(String[] args) {
        try {
            // Create a URL object for the JAR file
            URL jarUrl = new URL("jar:file:/path/to/myJarFile.jar!/");

            // Open a connection to the JAR file
            JarURLConnection jarConnection = (JarURLConnection) jarUrl.openConnection();

            // Get the JarEntry object for the file to be read
            JarEntry jarEntry = jarConnection.getJarEntry("myFile.txt");

            // Read the contents of the file
            InputStream inputStream = jarConnection.getInputStream(jarEntry);
            byte[] data = new byte[inputStream.available()];
            inputStream.read(data);
            String fileContents = new String(data);

            // Print the contents of the file
            System.out.println(fileContents);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

In this code, we first create a URL object for the JAR file we want to read. Note that the URL must include the "jar:" protocol and the "!" separator between the JAR file path and the resource path.

Next, we open a JarURLConnection to the JAR file, and retrieve the JarEntry object for the file we want to read. We then use the getInputStream method of the JarURLConnection to obtain an input stream to the file, which we can read to obtain its contents.

Finally, we print the contents of the file to the console. Note that this code can be used to read any file from the JAR file, not just text files.