Reading property files from java.

In real time application deployment, few values for application will be changing from environment to environment. Example, Database details. In development, Testing and in production environments we use different JDBC connection details. So hard coding this details in the code is not a good approach. Because every time we change these details we need to recreate the EAR and deploy. Instead we can refer these values from external file and use in the code, we no need to recreate EAR every time when we change environments. Or any other application properties which will change time to time from environment to environment.

To handle the above scenario we have option called properties files. Property file is simple flat text file which stores key-value information like java.util.Map. In runtime, we read this property file and get the value for which key we need the code. Below is the sample property file.

------------------------------------------------------------------------------------

MAILING_LIST = userAdminGroup@test.com

URL=https://devurl.test.com/url/faces/apps/pop/app/ui/page/Summary.jspx

IDM_SERVICE_URL=https://idm.test.com/OIMPortalServices/PortalSOAP?WSDL

OIM_USER_ID = dileepkumarrongaliblog@cswg.com

OIM_PASSWORD = test1234

-------------------------------------------------------------------------------------

In the below example I would like to explain how to read the property file key-pair values in java code. In the below example I am reading the OIM_USER_ID information.

import java.io.FileInputStream;

import java.io.IOException;

import java.util.Enumeration;

import java.util.Properties;

import oracle.adf.share.logging.ADFLogger;

public class ReadPropertyFile {

    //logger class

    private static ADFLogger _logger =  ADFLogger.createADFLogger(ReadPropertyFile .class);

    //Property file name

    public static final String PROPERTY_FILE_NAME = "MYEXAMPLE.properties"; 

    // file seperator to work accordinlgy in windows and unix systems.

    public static final String FILE_SEPERATOR = System.getProperty("file.separator");

    //if you deploye your appllication in Weblogic server change below value accordingly to your server path of file.

    //public static final String SERVER_PROPERTY_FILE_LOCATION =System.getProperty("wls.home") + FILE_SEPERATOR + "propertyFile";

    //Just for demo purpose I have put the file in below location

    public static final String SERVER_PROPERTY_FILE_LOCATION = "D:\\Examples\\build\\propertyFile";

     //Complete file path

     public static final String SERVER_PROPERTY_FILE = SERVER_PROPERTY_FILE_LOCATION + FILE_SEPERATOR + PROPERTY_FILE_NAME;

    public ReadPropertyFile() {

        super();

    }

   

    public String getPropConstant(String key) {

       Properties propertiesBundle = new Properties();

            try {

                String propertyFilePath = SERVER_PROPERTY_FILE;

               

                //path of properties file

                _logger.info("PROERTIES FILE PATH IS:::::::::: "+propertyFilePath);

               

                if (propertyFilePath != null) {

                    //get file input stream

                    FileInputStream in = new FileInputStream(propertyFilePath);                  

                    //load the property bundle

                    propertiesBundle.load(in);

                    //get all the keys in the property file.

                    Enumeration em = propertiesBundle.keys();

                    //iterate over the keys

                    while (em.hasMoreElements()) {

                        String keyStr = em.nextElement().toString();

                        String value = (String)propertiesBundle.get(keyStr);

                        if(value != null && !"".equals(value) && keyStr.equals(key)){

                            return value;

                        }

                    }

                }

            } catch (IOException e) {

                _logger.log(ADFLogger.ERROR, "Error getting Property file :"+ e.getStackTrace().toString());

            }

            return null;

    }

   

    public static void main(String[] args) {

        ReadPropertyFile readPropertyFile = new ReadPropertyFile();

        //reading property value for given key.

        String value = readPropertyFile.getPropConstant("OIM_USER_ID");

        System.out.println("---OIM_USER_ID-----"+value);

    }

}