Blick in das JNDI …

Manchmal muss man einfach in einen vorhanden JNDI reinschauen, um herauszufinden, was dort eigentlich auf Entdeckung schlummert. Die folgende Klasse liefert einen formatierten Baum aus den JNDI-Eintragungen.

package de.kaiserpfalzedv.office.common.jndi;

import javax.naming.InitialContext;
import javax.naming.NameClassPair;
import javax.naming.NamingEnumeration;
import javax.naming.NamingException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A small utlitiy class to print the JNDI tree.
 *
 * @author klenkes {@literal <rlichti@kaiserpfalz-edv.de>}
 * @version 1.0.0
 * @since 2016-09-29
 */
public class JndiWalker {
  private static final Logger LOG = LoggerFactory.getLogger(JndiWalker.class);

  /**
    * Walks the {@link InitialContext} with the entry point given and returns a string containing all sub entries.
    *
    * @param context The initial context to be printed.
    * @param entryPoint The node to start with.
    * @return A string containing the tree of the initial context (nodes including the leaves).
    * @throws NamingException If the lookup failes for some unknown reason.
    */
  public String walk(final InitialContext context, final String entryPoint) throws NamingException {
    StringBuffer sb = new StringBuffer(" JNDI tree for '").append(entryPoint).append("': ");

    LOG.trace("JNDI-Walker activated for entry point '{}' on: {}", entryPoint, context);
    walk(sb, context, entryPoint, 0);

    return sb.toString();
  }

  private void walk(
          StringBuffer sb,
          final InitialContext context,
          final String name,
          final int level
  ) throws NamingException {
    NamingEnumeration ne;
    try {
      ne = context.list(name);
    } catch (NamingException e) {
      LOG.trace("Reached leaf of JNDI: {}", name);
      return;
    }

    while (ne.hasMoreElements()) {
      NameClassPair ncp = (NameClassPair) ne.nextElement();

      printLevel(sb, level);

      sb
          .append(ncp.getName())
          .append(" (").append(ncp.getClassName())
          .append(", ").append(getNameInNamespace(ncp))
          .append(", ").append(getRelativeFlag(ncp))
          .append(")");

      walk(sb, context, name + "/" + ncp.getName(), level + 4);
    }
  }

  private void printLevel(StringBuffer sb, int level) {
    sb.append("\n");
    for (int i=0; i < level; i++) {
      sb.append(" ");
    }
  }

  private String getNameInNamespace(NameClassPair ncp) {
    String nameInNamespace;
    try {
      nameInNamespace = ncp.getNameInNamespace();
    } catch (UnsupportedOperationException e) {
      nameInNamespace = "not-supported";
    }
    return nameInNamespace;
  }

  private String getRelativeFlag(NameClassPair ncp) {
    String isRelative;
    try {
      isRelative = ncp.isRelative() ? "relative" : "fixed";
    } catch (UnsupportedOperationException e) {
      isRelative = "not-supported";
    }
    return isRelative;
  }
}

Die Basis für diese kleine Hilfsklasse war ein Blogeintrag von Anders Rudklaer Norgaard. Ich habe sie nur Servlet-unabhängig gemacht.