Settings bean - parameterized method call from EL

/**
 * Settings bean
 */
package nl.thimojansenit.bean;
 
import java.io.Serializable;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
 
import nl.thimojansenit.DummyMap;
 
/**
 * @author Thimo Jansen <thimo@jansenit.nl>
 */
public class Settings implements Serializable {
 
 private static final long serialVersionUID = 1L;
 private Map<String, Cache> _cache = new HashMap<String, Cache>();
 
 /**
  * Retrieve cached value of setting. If not yet cached or value is too old (> 60 minutes), get fresh value
  *
  * @param name
  *            of setting to retrieve
  * @return value of setting
  */
 public String getValue(String name) {
  Date now = new Date();
  if (!_cache.containsKey(name) || (now.getTime() - _cache.get(name).getDatetime().getTime()) > 1000 * 60 * 60) {
   _cache.put(name, new Cache(getFromMap(name)));
  }
 
  return _cache.get(name).getValue();
 }
 
 /**
  * Get SettingsMap object through which EL can fetch the value for a setting
  *
  * @return SettingsMap
  */
 public SettingsMap getValue() {
  return new SettingsMap(this);
 }
 
 /**
  * Static method to retrieve settings, replace this code with your own logic
  */
 static private String getFromMap(String name) {
  Map<String, String> settings = new HashMap<String, String>();
  settings.put("hostname", "www.thimojansenit.nl");
  settings.put("db_names", "names.nsf");
 
  return settings.get(name);
 }
 
 /**
  * InnerClass used to provide settings to EL. This class uses the parent bean to fetch values for settings
  */
 @SuppressWarnings("unchecked")
 private class SettingsMap extends DummyMap implements Map {
  // Reference to parent Settings bean
  private Settings _settings;
 
  public SettingsMap(Settings settings) {
   _settings = settings;
  }
 
  public Object get(Object obj) {
   return _settings.getValue((String) obj);
  }
 }
 
 /**
  * InnerClass used to store cached values, includes date/time stamp
  */
 private class Cache {
  private Date _datetime;
  private String _value;
 
  public Cache(String value) {
   _datetime = new Date();
   _value = value;
  }
 
  public Date getDatetime() {
   return _datetime;
  }
 
  public String getValue() {
   return _value;
  }
 }
}

/*
 * Support class DummyMap
 */

package nl.thimojansenit;
 
import java.util.Collection;
import java.util.Map;
import java.util.Set;
 
// abstract class used by java server faces to pass parameter to a method as map key
@SuppressWarnings("unchecked")
public abstract class DummyMap implements Map {
 public Collection values() {
  return null;
 }
 
 public Object put(Object key, Object value) {
  return null;
 }
 
 public Set keySet() {
  return null;
 }
 
 public boolean isEmpty() {
  return false;
 }
 
 public int size() {
  return 0;
 }
 
 public void putAll(Map t) {
 }
 
 public void clear() {
 }
 
 public boolean containsValue(Object value) {
  return false;
 }
 
 public Object remove(Object key) {
  return null;
 }
 
 public boolean containsKey(Object key) {
  return false;
 }
 
 public Set entrySet() {
  return null;
 }
 
 // subclasses should override this method call their method with obj as the parameter
 public abstract Object get(Object obj);
}