CODEWITHSUNDEEP
javaconfig
Bukas
Bukas

Reputation: 35

How to attach file to jar that can be edited inside this jar?

I am making a program that works with MySQL database,for now i store URL, login, password e.t.c as public static String. Now i need to make it possible to work on another computer, so database adress will vary, so i need a way to edit it inside programm and save. I would like to use just external txt file, but i don't know how to point it's location.

I decided to make it using Property file, i put it in src/res folder. It work correct while i'm trying it inside Intellij Idea, but when i build jar (artifact) i get java.io.FileNotFoundException

I tried two ways: This one was just copied private String getFile(String fileName) {

    StringBuilder result = new StringBuilder("");

    //Get file from resources folder
    ClassLoader classLoader = getClass().getClassLoader();
    File file = new File(classLoader.getResource(fileName).getFile());
    System.out.println(file.length());

    try (Scanner scanner = new Scanner(file)) {

        while (scanner.hasNextLine()) {
            String line = scanner.nextLine();
            result.append(line).append("\n");
        }

        scanner.close();

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

    return result.toString();

}
System.out.println(obj.getFile("res/cfg.txt"));</code>

And second one using Properties class:

try(FileReader reader =  new FileReader("src/res/cfg.txt")) {
Properties properties = new Properties();
properties.load(reader);
System.out.println(properties.get("password"));
}catch (Exception e) {
e.printStackTrace();
System.out.println(e);
}

In both ways i get java.io.FileNotFoundException. What is right way to attach config file like that?

Upvotes: 2

Views: 77

Answers (2)

rustyx
rustyx

Reputation: 85361

Since the file is inside a .JAR, it can't be accessed via new File(), but you can still read it via the ClassLoader:

Properties properties = new Properties();
try (InputStream stream = getClass().getResourceAsStream("/res/cfg.txt")) {
    properties.load(stream);
}

Note that a JAR is read-only. So this approach won't work.

If you want to have editable configuration, you should place your cfg.txt outside the JAR and read it from the filesystem. For example like this:

Properties properties = new Properties();
File appPath = new File(MyClass.class.getProtectionDomain().getCodeSource().getLocation().toURI()).getParentFile();
try (InputStream stream = new FileInputStream(new File(appPath, "cfg.txt"))) {
    properties.load(stream);
}

Upvotes: 3

Elliott Frisch
Elliott Frisch

Reputation: 201447

There are multiple places your can place your configuration options, and a robust deployment strategy will utilize some (or all) of the following techniques:

  • Storing configuration files in a well known location relative to the user's home folder as I mentioned in the comments. This works on Windows (C:\Users\efrisch), Linux (/home/efrisch) and Mac (/Users/efrisch)

    File f = new File(System.getProperty("user.home"), "my-settings.txt");

  • Reading environment variables to control it

    File f = new File(System.getenv("DEPLOY_DIR"), "my-settings.txt");

  • Using a decentralized service such as Apache ZooKeeper to store your database settings

  • Use Standalone JNDI (or the JNDI built-in to your deployment target)

  • Use a Connection Pool

Upvotes: 1

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