Concrete subclass of {@link LogFactory} specific to log4j.
+ *
+ * @author Costin Manolache
+ */
+public final class Log4jFactory extends LogFactory {
+
+ public Log4jFactory() {
+ super();
+ }
+
+ /**
+ * The configuration attributes for this {@link LogFactory}.
+ */
+ private Hashtable attributes = new Hashtable();
+
+ // previously returned instances, to avoid creation of proxies
+ private Hashtable instances = new Hashtable();
+
+ // --------------------------------------------------------- Public Methods
+
+ /**
+ * Return the configuration attribute with the specified name (if any),
+ * or null if there is no such attribute.
+ *
+ * @param name Name of the attribute to return
+ */
+ public Object getAttribute(String name) {
+ return (attributes.get(name));
+ }
+
+
+ /**
+ * Return an array containing the names of all currently defined
+ * configuration attributes. If there are no such attributes, a zero
+ * length array is returned.
+ */
+ public String[] getAttributeNames() {
+ Vector names = new Vector();
+ Enumeration keys = attributes.keys();
+ while (keys.hasMoreElements()) {
+ names.addElement((String) keys.nextElement());
+ }
+ String results[] = new String[names.size()];
+ for (int i = 0; i < results.length; i++) {
+ results[i] = (String) names.elementAt(i);
+ }
+ return (results);
+ }
+
+
+ /**
+ * Convenience method to derive a name from the specified class and
+ * call getInstance(String) with it.
+ *
+ * @param clazz Class for which a suitable Log name will be derived
+ *
+ * @exception LogConfigurationException if a suitable Log
+ * instance cannot be returned
+ */
+ public Log getInstance(Class clazz)
+ throws LogConfigurationException
+ {
+ Log instance = (Log) instances.get(clazz);
+ if( instance != null )
+ return instance;
+
+ instance=new Log4JCategoryLog( Category.getInstance( clazz ));
+ instances.put( clazz, instance );
+ return instance;
+ }
+
+
+ public Log getInstance(String name)
+ throws LogConfigurationException
+ {
+ Log instance = (Log) instances.get(name);
+ if( instance != null )
+ return instance;
+
+ instance=new Log4JCategoryLog( Category.getInstance( name ));
+ instances.put( name, instance );
+ return instance;
+ }
+
+
+ /**
+ * Release any internal references to previously created {@link Log}
+ * instances returned by this factory. This is useful environments
+ * like servlet containers, which implement application reloading by
+ * throwing away a ClassLoader. Dangling references to objects in that
+ * class loader would prevent garbage collection.
+ */
+ public void release() {
+
+ instances.clear();
+
+ // what's the log4j mechanism to cleanup ???
+ }
+
+
+ /**
+ * Remove any configuration attribute associated with the specified name.
+ * If there is no such attribute, no action is taken.
+ *
+ * @param name Name of the attribute to remove
+ */
+ public void removeAttribute(String name) {
+ attributes.remove(name);
+ }
+
+
+ /**
+ * Set the configuration attribute with the specified name. Calling
+ * this with a null value is equivalent to calling
+ * removeAttribute(name).
+ *
+ * @param name Name of the attribute to set
+ * @param value Value of the attribute to set, or null
+ * to remove any setting for this attribute
+ */
+ public void setAttribute(String name, Object value) {
+ if (value == null) {
+ attributes.remove(name);
+ } else {
+ attributes.put(name, value);
+ }
+ }
+
+}