javaURLContextFactory.java

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 * Copyright 2004 The Apache Software Foundation
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package org.apache.naming.java;

import java.util.Hashtable;
import javax.naming.Name;
import javax.naming.Context;
import javax.naming.NamingException;
import javax.naming.spi.ObjectFactory;
import javax.naming.spi.InitialContextFactory;
import org.apache.naming.SelectorContext;
import org.apache.naming.NamingContext;
import org.apache.naming.ContextBindings;

/**
 * Context factory for the "java:" namespace.
 * <p>
 * <b>Important note</b> : This factory MUST be associated with the "java" URL
 * prefix, which can be done by either :
 * <ul>
 * <li>Adding a 
 * java.naming.factory.url.pkgs=org.apache.catalina.util.naming property
 * to the JNDI properties file</li>
 * <li>Setting an environment variable named Context.URL_PKG_PREFIXES with 
 * its value including the org.apache.catalina.util.naming package name. 
 * More detail about this can be found in the JNDI documentation : 
 * {@link javax.naming.spi.NamingManager#getURLContext(java.lang.String, java.util.Hashtable)}.</li>
 * </ul>
 * 
 * @author Remy Maucherat
 * @version $Revision: 1.2 $ $Date: 2005/12/08 01:29:08 $
 */

public class javaURLContextFactory
    implements ObjectFactory, InitialContextFactory {


    // ----------------------------------------------------------- Constructors


    // -------------------------------------------------------------- Constants


    public static final String MAIN = "initialContext";


    // ----------------------------------------------------- Instance Variables


    /**
     * Initial context.
     */
    protected static volatile Context initialContext = null;


    // --------------------------------------------------------- Public Methods


    // -------------------------------------------------- ObjectFactory Methods


    /**
     * Crete a new Context's instance.
     */
    public Object getObjectInstance(Object obj, Name name, Context nameCtx,
                                    Hashtable<?,?> environment)
        throws NamingException {
        if ((ContextBindings.isThreadBound()) || 
            (ContextBindings.isClassLoaderBound())) {
            return new SelectorContext(castEnvironment(environment));
        } else {
            return null;
        }
    }


    /**
     * Get a new (writable) initial context.
     */
    public Context getInitialContext(Hashtable<?,?> environment)
        throws NamingException {
        if (ContextBindings.isThreadBound() || 
            (ContextBindings.isClassLoaderBound())) {
            // Redirect the request to the bound initial context
            return new SelectorContext(castEnvironment(environment), true);
        }

        // If the thread is not bound, return a shared writable context
        if (initialContext == null) {
            synchronized(javaURLContextFactory.class) {
                if (initialContext == null) {
                    initialContext = new NamingContext(
                            castEnvironment(environment), MAIN);
                }
            }
        }
        return initialContext;
    }

    @SuppressWarnings("unchecked")
    private Hashtable<String, Object> castEnvironment(Hashtable<?,?> env) {
        return (Hashtable<String, Object>)env;
    }
}