CODEWITHSUNDEEP
javapropertiespathjar
Lehane
Lehane

Reputation: 48668

Reading properties file from JAR directory

I’m creating an executable JAR that will read in a set of properties at runtime from a file. The directory structure will be something like:

/some/dirs/executable.jar
/some/dirs/executable.properties

Is there a way of setting the property loader class in the executable.jar file to load the properties from the directory that the jar is in, rather than hard-coding the directory.

I don't want to put the properties in the jar itself as the properties file needs to be configurable.

Upvotes: 5

Views: 11386

Answers (2)

amsathishkumar
amsathishkumar

Reputation: 11

public static void loadJarCongFile(Class Utilclass )
    {
       try{         
             String path= Utilclass.getResource("").getPath();
             path=path.substring(6,path.length()-1);
             path=path.split("!")[0];
             System.out.println(path);
             JarFile jarFile = new JarFile(path);

               final Enumeration<JarEntry> entries = jarFile.entries();
               while (entries.hasMoreElements()) {
                   final JarEntry entry = entries.nextElement();
                   if (entry.getName().contains(".properties")) {
                       System.out.println("Jar File Property File: " + entry.getName());
                       JarEntry fileEntry = jarFile.getJarEntry(entry.getName());
                       InputStream input = jarFile.getInputStream(fileEntry);
                       setSystemvariable(input);      
                       InputStreamReader isr = new InputStreamReader(input); 
                       BufferedReader reader = new BufferedReader(isr);
                       String line;
                    
                       while ((line = reader.readLine()) != null) {
                           System.out.println("Jar file"+line);
                       }
                       reader.close();
                   }
               }
       }
       catch (Exception e)
       {
          System.out.println("Jar file reading Error");
       }
    }
    public static void setSystemvariable(InputStream input)
    {
    Properties tmp1 = new Properties();
       try {
             tmp1.load(input);

       for (Object element : tmp1.keySet()) {
             System.setProperty(element.toString().trim(),
                           tmp1.getProperty(element.toString().trim()).trim());
             }      
       } catch (IOException e) {
             System.out.println("setSystemvariable method failure");
       }
    }

Upvotes: 0

Adamski
Adamski

Reputation: 54705

Why not just pass the properties file as an argument to your main method? That way you can load the properties as follows:

public static void main(String[] args) throws IOException {
  Properties props = new Properties();
  props.load(new BufferedReader(new FileReader(args[0])));
  System.setProperties(props);
}

The alternative: If you want to get the current directory of your jar file you need to do something nasty like:

CodeSource codeSource = MyClass.class.getProtectionDomain().getCodeSource();
File jarFile = new File(codeSource.getLocation().toURI().getPath());
File jarDir = jarFile.getParentFile();

if (jarDir != null && jarDir.isDirectory()) {
  File propFile = new File(jarDir, "myFile.properties");
}

... where MyClass is a class from within your jar file. It's not something I'd recommend though - What if your app has multiple MyClass instances on the classpath in different jar files (each jar in a different directory)? i.e. You can never really guarantee that MyClass was loaded from the jar you think it was.

Upvotes: 13

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