// ========================================================================
// $Id: ContextFactory.java 1327 2006-11-27 18:40:14Z janb $
// Copyright 1999-2006 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ========================================================================
package org.mortbay.naming;
import java.util.Hashtable;
import java.util.WeakHashMap;
import javax.naming.Context;
import javax.naming.Name;
import javax.naming.NameParser;
import javax.naming.Reference;
import javax.naming.StringRefAddr;
import javax.naming.spi.ObjectFactory;
import org.mortbay.jetty.handler.ContextHandler;
import org.mortbay.log.Log;
/**
* ContextFactory.java
*
* This is an object factory that produces a jndi naming
* context based on a classloader.
*
* It is used for the java:comp context.
*
* This object factory is bound at java:comp. When a
* lookup arrives for java:comp, this object factory
* is invoked and will return a context specific to
* the caller's environment (so producing the java:comp/env
* specific to a webapp).
*
* The context selected is based on classloaders. First
* we try looking in at the classloader that is associated
* with the current webapp context (if there is one). If
* not, we use the thread context classloader.
*
* Created: Fri Jun 27 09:26:40 2003
*
* @author <a href="mailto:janb@mortbay.com">Jan Bartel</a>
*
*/
public class ContextFactory implements ObjectFactory
{
/**
* Map of classloaders to contexts.
*/
private static WeakHashMap _contextMap;
/**
* Threadlocal for injecting a context to use
* instead of looking up the map.
*/
private static ThreadLocal _threadContext;
static
{
_contextMap = new WeakHashMap();
_threadContext = new ThreadLocal();
}
/**
* Find or create a context which pertains to a classloader.
*
* We use either the classloader for the current ContextHandler if
* we are handling a request, OR we use the thread context classloader
* if we are not processing a request.
* @see javax.naming.spi.ObjectFactory#getObjectInstance(java.lang.Object, javax.naming.Name, javax.naming.Context, java.util.Hashtable)
*/
public Object getObjectInstance (Object obj,
Name name,
Context nameCtx,
Hashtable env)
throws Exception
{
//First, see if we have had a context injected into us to use.
Context ctx = (Context)_threadContext.get();
if (ctx != null)
{
if(Log.isDebugEnabled()) Log.debug("Using the Context that is bound on the thread");
return ctx;
}
// Next, see if we are in a webapp context, if we are, use
// the classloader of the webapp to find the right jndi comp context
ClassLoader loader = null;
if (ContextHandler.getCurrentContext() != null)
{
loader = ContextHandler.getCurrentContext().getContextHandler().getClassLoader();
}
if (loader != null)
{
if (Log.isDebugEnabled()) Log.debug("Using classloader of current org.mortbay.jetty.handler.ContextHandler");
}
else
{
//Not already in a webapp context, in that case, we try the
//curren't thread's classloader instead
loader = Thread.currentThread().getContextClassLoader();
if (Log.isDebugEnabled()) Log.debug("Using thread context classloader");
}
//Get the context matching the classloader
ctx = (Context)_contextMap.get(loader);
//The map does not contain an entry for this classloader
if (ctx == null)
{
//Check if a parent classloader has created the context
ctx = getParentClassLoaderContext(loader);
//Didn't find a context to match any of the ancestors
//of the classloader, so make a context
if (ctx == null)
{
Reference ref = (Reference)obj;
StringRefAddr parserAddr = (StringRefAddr)ref.get("parser");
String parserClassName = (parserAddr==null?null:(String)parserAddr.getContent());
NameParser parser = (NameParser)(parserClassName==null?null:loader.loadClass(parserClassName).newInstance());
ctx = new NamingContext (env,
name.get(0),
nameCtx,
parser);
if(Log.isDebugEnabled())Log.debug("No entry for classloader: "+loader);
_contextMap.put (loader, ctx);
}
}
return ctx;
}
/**
* Keep trying ancestors of the given classloader to find one to which
* the context is bound.
* @param loader
* @return
*/
public Context getParentClassLoaderContext (ClassLoader loader)
{
Context ctx = null;
ClassLoader cl = loader;
for (cl = cl.getParent(); (cl != null) && (ctx == null); cl = cl.getParent())
{
ctx = (Context)_contextMap.get(cl);
}
return ctx;
}
/**
* Associate the given Context with the current thread.
* resetComponentContext method should be called to reset the context.
* @param ctx the context to associate to the current thread.
* @return the previous context associated on the thread (can be null)
*/
public static Context setComponentContext(final Context ctx)
{
Context previous = (Context)_threadContext.get();
_threadContext.set(ctx);
return previous;
}
/**
* Set back the context with the given value.
* Don't return the previous context, use setComponentContext() method for this.
* @param ctx the context to associate to the current thread.
*/
public static void resetComponentContext(final Context ctx)
{
_threadContext.set(ctx);
}
}