Using Java Properties File

Many programmers use properties files for keeping configuration parameters (DB Server IP etc.)

Here is a sample class code for accessing configuration parameters from a properties file. You can pass JVM parameter like this :

java -DMyPropertiesFile=/usr/local/java/proj/myconfig.properties MyClass

package javacream;

import java.io.InputStream;
import java.util.Properties;

public class AppProperties {
 private static Properties prop;

 static {
  initiate();
 }

 protected static void initiate() {
  try {
   //Pass Java VM following arguement
   // -DMyPropertiesFile="[PATH]/[PROPERTIESFILENAME]"

   prop = new Properties();

   String propertiesFile = System.getProperty("MyPropertiesFile");

   if (propertiesFile == null) {
    System.out
      .println("Could not find content.properties property in System Properties.");
    System.out
      .println("This property file is needed for the application to operate.");
    System.out
      .println("Send this parameter as -DMyPropertiesFile=%FILENAME% to java vm.");

    propertiesFile = "myconfiguration.properties";

    System.out
      .println("Setting properties file name to default value "
        + propertiesFile);

   }

   try {
    InputStream is = new java.io.FileInputStream(propertiesFile);

    prop.load(is);
   } catch (Exception e) {
    e.printStackTrace();

    System.out.println("Could not read or find MyPropertiesFile");
    System.out
      .println("This property file is needed for the application to operate.");
    System.out
      .println("Send this parameter as -MyPropertiesFile=%FILENAME% to java vm.");
    return;
   }
  } catch (Throwable t) {
   t.printStackTrace();

   return;
  }

 }

 public static String get(String key) {
  String value = prop.getProperty(key);
  if ((value == null) && !prop.containsKey(key)) {
   System.out.println("Could not find the key " + key
     + " in Properties file.");

  }
  return (value);
 }

 public static String get(String key, String defaultValue) {
  String value = prop.getProperty(key);

  if ((value == null) && !prop.containsKey(key)) {
   System.out.println("Could not find the key " + key
     + " in Properties file, using default value");
  }

  return (prop.getProperty(key, defaultValue));

 }

 public static void main(String[] args) {
  System.out.println(AppProperties.get("UserName"));
 }

}