abstractcontext.java

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/*
 * Copyright (C) The Apache Software Foundation. All rights reserved.
 *
 * This software is published under the terms of the Apache Software License
 * version 1.1, a copy of which has been included with this distribution in
 * the LICENSE file.
 */
package org.apache.avalon.excalibur.naming;

import java.util.Hashtable;
import javax.naming.*;
import javax.naming.Context;

/**
 * Abstract JNDI Context that can be inherited from to
 * provide a particular type of Context.
 *
 * @author <a href="mailto:[e-mail]">Peter Donald</a>
 * @version $Revision: 1.2 $
 */
public abstract class AbstractContext
    implements Context
{
    protected Hashtable  m_environment;

    public AbstractContext()
    {
        this( new Hashtable() );
    }

    public AbstractContext( final Hashtable environment )
    {
        m_environment = environment;
    }

    protected abstract NameParser getNameParser()
        throws NamingException;

    /**
     * Add a key-value pair to environment
     *
     * @param key the key
     * @param value the value
     * @return the value
     */
    public Object addToEnvironment( final String key, final Object value )
        throws NamingException
    {
        if( null == m_environment ) m_environment = new Hashtable( 5, 0.75f );
        return m_environment.put( key, value );
    }

    /**
     * Release resources associated with context.
     *
     */
    public void close()
    {
        m_environment = null;
    }

    protected boolean isSelf( final Name name )
    {
        return ( name.isEmpty() || name.get( 0 ).equals( "" ) );
    }

    /**
     * Bind an object to a name.
     *
     * @param name the name to bind to
     * @param object the object
     * @exception NamingException if an error occurs such as bad name or invalid binding
     */
    public void bind( final String name, final Object object )
        throws NamingException
    {
        bind( getNameParser().parse( name ), object );
    }

    /**
     * Bind an object to a name.
     *
     * @param name the name to bind to
     * @param object the object
     * @exception NamingException if an error occurs such as bad name or invalid binding
     */
    public void bind( final Name name, final Object object )
        throws NamingException
    {
        bind( name, object, false );
    }

    /**
     * Helper method to bind
     */
    protected abstract void bind( Name name, Object object, boolean rebind )
        throws NamingException;

    /**
     * Compose a name form a name and a prefix.
     *
     * @param name the name
     * @param prefix the prefix
     * @return the composed name
     * @exception NamingException if a badly formatted name for context
     */
    public String composeName( final String name, final String prefix )
        throws NamingException
    {
        final NameParser nameParser = getNameParser();
        final Name result =
            composeName( nameParser.parse( name ), nameParser.parse( prefix ) );
        return result.toString();
    }

    /**
     * Compose a name form a name and a prefix.
     *
     * @param name the name
     * @param prefix the prefix
     * @return the composed name
     * @exception NamingException if a badly formatted name for context
     */
    public Name composeName( final Name name, final Name prefix )
        throws NamingException
    {
        final Name result = (Name)(prefix.clone());
        result.addAll( name );
        return result;
    }

    /**
     * Create a Subcontext.
     *
     * @param name the name of subcontext
     * @return the created context
     * @exception NamingException if an error occurs (ie context exists, badly formated name etc)
     */
    public Context createSubcontext( final String name )
        throws NamingException
    {
        return createSubcontext( getNameParser().parse( name ) );
    }

    /**
     * Destroy a Subcontext.
     *
     * @param name the name of subcontext to destroy
     * @exception NamingException if an error occurs such as malformed name or
     *            context not exiting or not empty
     */
    public void destroySubcontext( final String name )
        throws NamingException
    {
        destroySubcontext( getNameParser().parse( name ) );
    }

    /**
     * Return a copy of environment.
     *
     * @return the environment
     */
    public Hashtable getEnvironment()
        throws NamingException
    {
        if( null == m_environment ) return new Hashtable( 3, 0.75f );
        else return (Hashtable)m_environment.clone();
    }

    /**
     * Get the NameParser for the named context.
     *
     * @param name
     * @return the NameParser
     * @exception NamingException if an error occurs
     */
    public NameParser getNameParser( final String name )
        throws NamingException
    {
        return getNameParser( getNameParser().parse( name ) );
    }

    /**
     * Get the NameParser for the named context.
     *
     * @param name
     * @return the NameParser
     * @exception NamingException if an error occurs
     */
    public NameParser getNameParser( final Name name )
        throws NamingException
    {
        if( name.isEmpty() )
        {
            return getNameParser();
        }

        Object object = lookup( name );
        if( !(object instanceof Context) )
        {
            object = lookup( getPathName( name ) );
        }

        final Context context = (Context)object;
        final NameParser parser = context.getNameParser( "" );
        context.close();
        return parser;
    }

    /**
     * Enumerates the names bound in the named context, along with the objects bound to them.
     *
     * @param name the name of the context
     * @return the enumeration
     * @exception NamingException if an error occurs
     */
    public NamingEnumeration list( final String name )
        throws NamingException
    {
        return list( getNameParser().parse( name ) );
    }

    /**
     * Enumerates the names bound in the named context, along with the objects bound to them.
     *
     * @param name the name of the context
     * @return the enumeration
     * @exception NamingException if an error occurs
     */
    public NamingEnumeration listBindings( final String name )
        throws NamingException
    {
        return listBindings( getNameParser().parse( name ) );
    }

    /**
     * Get the object named.
     *
     * @param name the name
     * @return the object
     * @exception NamingException if an error occurs (ie object name is inavlid or unbound)
     */
    public Object lookup( final String name )
        throws NamingException
    {
        return lookup( getNameParser().parse( name ) );
    }

    /**
     * Get the object named following all links.
     *
     * @param name the name
     * @return the object
     * @exception NamingException if an error occurs (ie object name is inavlid or unbound)
     */
    public Object lookupLink( final String name )
        throws NamingException
    {
        return lookupLink( getNameParser().parse( name ) );
    }

    /**
     * Get the object named following all links.
     *
     * @param name the name
     * @return the object
     * @exception NamingException if an error occurs (ie object name is inavlid or unbound)
     */
    public Object lookupLink( final Name name )
        throws NamingException
    {
        return lookup( name );
    }

    /**
     * Binds a name to an object, overwriting any existing binding.
     *
     * @param name the name
     * @param object the object
     * @exception NamingException if an error occurs
     */
    public void rebind( final String name, final Object object )
        throws NamingException
    {
        rebind( getNameParser().parse( name ), object );
    }

    /**
     * Binds a name to an object, overwriting any existing binding.
     *
     * @param name the name
     * @param object the object
     * @exception NamingException if an error occurs
     */
    public void rebind( final Name name, final Object object )
        throws NamingException
    {
        bind( name, object, true );
    }

    /**
     * Remove a key-value pair form environment and return it.
     *
     * @param key the key
     * @return the value
     */
    public Object removeFromEnvironment( final String key )
        throws NamingException
    {
        if( null == m_environment ) return null;
        return m_environment.remove( key );
    }

    /**
     * Rename a already bound object
     *
     * @param oldName the old name
     * @param newName the new name
     * @exception NamingException if an error occurs
     */
    public void rename( final String oldName, final String newName )
        throws NamingException
    {
        rename( getNameParser().parse( oldName ), getNameParser().parse( newName ) );
    }

    public void rename( final Name oldName, final Name newName )
        throws NamingException
    {
        if( isSelf( oldName ) || isSelf( newName ) )
        {
            throw new InvalidNameException( "Failed to rebind self" );
        }
        else if( oldName.equals( newName ) )
        {
            throw new InvalidNameException( "Failed to rebind identical names" );
        }

        bind( newName, lookup( oldName ) );
        unbind( oldName );
    }

    /**
     * Unbind a object from a name.
     *
     * @param name the name
     * @exception NamingException if an error occurs
     */
    public void unbind( final String name )
        throws NamingException
    {
        unbind( getNameParser().parse( name ) );
    }

    /**
     * Get name components minus leaf name component.
     *
     * @param name the name elements leading up to last element
     * @return the name
     * @exception NamingException if an error occurs
     */
    protected Name getPathName( final Name name )
        throws NamingException
    {
        return name.getPrefix( name.size() - 1 );
    }

    /**
     * Get leaf name component from specified Name object.
     *
     * @param name a value of type 'Name'
     * @return a value of type 'Name'
     * @exception NamingException if an error occurs
     */
    protected Name getLeafName( final Name name )
        throws NamingException
    {
        return name.getSuffix( name.size() - 1 );
    }
}