java - Reading a resource file from within jar

Java - Reading a resource file from within jar

To read a resource file from within a JAR file in Java, you can use the ClassLoader to obtain the input stream for the resource. Here's an example:

Suppose you have a JAR file named your-application.jar, and within this JAR, you have a resource file named example.txt located in the resources directory.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class ReadResourceFromJar {

    public static void main(String[] args) {
        // Specify the path to the resource file within the JAR
        String resourcePath = "resources/example.txt";

        try {
            // Use the class loader to obtain the input stream for the resource
            InputStream inputStream = ReadResourceFromJar.class.getClassLoader().getResourceAsStream(resourcePath);

            if (inputStream != null) {
                // Read the contents of the resource file
                BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
                String line;

                while ((line = reader.readLine()) != null) {
                    System.out.println(line);
                }

                reader.close();
            } else {
                System.out.println("Resource not found: " + resourcePath);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

In this example:

  • ReadResourceFromJar.class.getClassLoader().getResourceAsStream(resourcePath) obtains an input stream for the resource file specified by resourcePath. The getResourceAsStream method returns null if the resource is not found.
  • The input stream is then used to read the contents of the resource file, and each line is printed to the console.

Make sure to adjust the resourcePath variable according to the actual path of your resource file within the JAR. Also, ensure that the resource file is present in the specified location within the JAR file. The resources directory is used in this example, but you should adapt it to your specific file structure.

Examples

  1. "Java read text file from JAR"

    • Code Implementation:
      InputStream inputStream = getClass().getResourceAsStream("/path/to/file.txt");
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
    • Description: Reads a text file from within a JAR using getResourceAsStream() and InputStreamReader.

  2. "Java read properties file from JAR"

    • Code Implementation:
      Properties properties = new Properties();
InputStream inputStream = getClass().getResourceAsStream("/path/to/config.properties");
properties.load(inputStream);
    • Description: Loads properties from a file within a JAR using getResourceAsStream() and Properties class.

  3. "Java read XML file from JAR"

    • Code Implementation:
      InputStream inputStream = getClass().getResourceAsStream("/path/to/data.xml");
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.parse(inputStream);
    • Description: Parses an XML file from within a JAR using getResourceAsStream() and DocumentBuilder.

  4. "Java read JSON file from JAR"

    • Code Implementation:
      InputStream inputStream = getClass().getResourceAsStream("/path/to/data.json");
InputStreamReader reader = new InputStreamReader(inputStream);
JsonObject jsonObject = new JsonParser().parse(reader).getAsJsonObject();
    • Description: Reads a JSON file from within a JAR using getResourceAsStream() and Gson library.

  5. "Java read binary file from JAR"

    • Code Implementation:
      InputStream inputStream = getClass().getResourceAsStream("/path/to/binary.bin");
byte[] data = IOUtils.toByteArray(inputStream);
    • Description: Reads a binary file from within a JAR using getResourceAsStream() and Apache Commons IO library.

  6. "Java read resource file using ClassLoader"

    • Code Implementation:
      InputStream inputStream = getClass().getClassLoader().getResourceAsStream("path/to/file.txt");
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
    • Description: Uses ClassLoader to read a resource file from within a JAR.

  7. "Java read file from JAR as Stream"

    • Code Implementation:
      InputStream inputStream = getClass().getResourceAsStream("/path/to/file.txt");
Stream<String> lines = new BufferedReader(new InputStreamReader(inputStream)).lines();
    • Description: Reads a file from within a JAR as a stream of lines.

  8. "Java read resource file with absolute path"

    • Code Implementation:
      URL resourceUrl = getClass().getResource("/path/to/file.txt");
File file = new File(resourceUrl.toURI());
BufferedReader reader = new BufferedReader(new FileReader(file));
    • Description: Reads a resource file from within a JAR using an absolute path.

  9. "Java read multiple files from JAR"

    • Code Implementation:
      PathMatcher matcher = FileSystems.getDefault().getPathMatcher("glob:/path/to/*.txt");
try (FileSystem fs = FileSystems.newFileSystem(URI.create("jar:" + getClass().getProtectionDomain().getCodeSource().getLocation().toURI()), Collections.emptyMap())) {
    Files.walk(fs.getPath("/path/to"))
         .filter(matcher::matches)
         .forEach(System.out::println);
}
    • Description: Reads multiple files from within a JAR using Files.walk() and PathMatcher.

  10. "Java read resource file from another JAR"

    • Code Implementation:
      InputStream inputStream = OtherClass.class.getResourceAsStream("/path/to/file.txt");
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
    • Description: Reads a resource file from within another JAR by referencing a class from that JAR.

More Tags

dependency-management android-browser ubuntu-9.10 onscrolllistener chrome-ios arcmap bamboo library-path data-mining xssf

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