Can anyone please explain this code to me?

Question

I am a new (junior)programmer?Can anyone please explain this code to me in lame terms? I am working at a client location and found this code in a project.
_file name is AtccJndiTemplate.java_
Why do we use the Context class?
Why do we use the properties class?
package org.atcc.common.utils;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import java.util.logging.Logger;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import org.springframework.jndi.JndiTemplate;
public class AtccJndiTemplate extends JndiTemplate
  private static Logger logger = Logger.getLogger(AtccJndiTemplate.class.getName());
  private String jndiProperties;
  protected Context createInitialContext()
    throws NamingException
    Context context = null;
    InputStream in = null;
    Properties env = new Properties();
    logger.info("Load JNDI properties from classpath file " + this.jndiProperties);
    try
      in = AtccJndiTemplate.class.getResourceAsStream(this.jndiProperties);
      env.load(in);
      in.close();
    catch (NullPointerException e) {
      logger.warning("Did not read JNDI properties file, using existing properties");
      env = System.getProperties();
    } catch (IOException e) {
      logger.warning("Caught IOException for file [" + this.jndiProperties + "]");
      throw new NamingException(e.getMessage());
    logger.config("ENV: java.naming.factory.initial = " + env.getProperty
("java.naming.factory.initial"));
    logger.config("ENV: java.naming.factory.url.pkgs = " + env.getProperty
("java.naming.factory.url.pkgs"));
    logger.info("ENV: java.naming.provider.url = " + env.getProperty
("java.naming.provider.url") + " timeout=" + env.getProperty("jnp.timeout"));
    context = new InitialContext(env);
    return context;
  public String getJndiProperties()
    return this.jndiProperties;
  public void setJndiProperties(String jndiProperties)
    this.jndiProperties = jndiProperties;
}

Answer 1

Hi,
JNDI needs some property such as the
java.naming.factory.initial
java.naming.provider.url
which are needed by the
InitialContext(env);
where env is a properties object
Now if you can not find the physical property file on the class path
by AtccJndiTemplate.class.getResourceAsStream(this.jndiProperties);
where the String "jndiProperties" get injected by certain IOC ( inverse of control container ) such as Spring framework
if not found then it will take the property from the system which will come from the evniromental variables which are set during the application start up i.e through the command line
java -Djava.naming.factory.initial=com.sun.jndi.ldap.LdapCtxFactory -Danother=value etc..
I hope this could help
Regards,
Alan Mehio
London,UK