message.java

JXTA源文件

                throw failure;
            }
            
            current = (element) list.previous();
            return current.element;
        }
        
        /**
         *  {@inheritDoc}
         **/
        public int previousIndex() {
            return list.previousIndex();
        }
        
        /**
         *  {@inheritDoc}
         *
         *  <p/>Not provided because the namespace cannot be specified.
         **/
        public void add( Object obj ) {
            throw new UnsupportedOperationException( "add() not supported" );
        }
        
        /**
         *  {@inheritDoc}
         **/
        public void remove() {
            if( origModCount != Message.this.getMessageModCount() ) {
                RuntimeException failure = new ConcurrentModificationException( Message.this + " concurrently modified. Iterator was made at mod " + origModCount );
                
                if (LOG.isEnabledFor(Level.ERROR)) {
                    LOG.error( Message.this + " concurrently modified. iterator mod=" + origModCount + " current mod=" + Message.this.getMessageModCount() + "\n" + getMessageModHistory(), failure );
                }
                
                throw failure;
            }
            
            if( null == current ) {
                throw new IllegalStateException( "no current element, call next() or previous()" );
            }
            
            ListIterator elsPosition = Message.this.elements.listIterator();
            ListIterator nsPosition = ((List)( namespaces.get(current.namespace))).listIterator();
            
            int currentPrevious = list.previousIndex();
            
            // restart this iterator
            while( list.previousIndex() >= 0 ) {
                list.previous();
            }
            
            // readvance to the current position, but track in ns list and master list
            while( list.previousIndex() < currentPrevious ) {
                element anElement = (element) list.next();
                
                try {
                    // advance to the same element in the master list.
                    element anElsElement;
                    
                    do {
                        anElsElement = (element) elsPosition.next();
                    } while( anElement != anElsElement );
                    
                    // advance to the same element in the ns list.
                    MessageElement anNsElement;
                    
                    if( current.namespace.equals( anElement.namespace ) ) {
                        do {
                            anNsElement = (MessageElement) nsPosition.next();
                        } while( anElement.element != anNsElement );
                    }
                } catch ( NoSuchElementException ranOut ) {
                    RuntimeException failure = new ConcurrentModificationException( Message.this + " concurrently modified. Iterator was made at mod " + origModCount );
                    
                    if (LOG.isEnabledFor(Level.ERROR)) {
                        LOG.error( Message.this + " concurrently modified. iterator mod=" + origModCount + " current mod=" + Message.this.getMessageModCount() + "\n" + getMessageModHistory(), failure );
                    }
                    
                    throw failure;
                }
            }
            
            elsPosition.remove( );
            nsPosition.remove( );
            list.remove();
            origModCount = Message.this.incMessageModCount();
            if (LOG.isEnabledFor(Level.DEBUG)) {
                LOG.debug("Removed " + current.namespace + "::" + current.element.getElementName() + "/" + current.element.getClass().getName() + "@" + current.element.hashCode() + " from " +  Message.this );
            }
            current = null;
        }
        
        /**
         *  {@inheritDoc}
         *
         *  <p/>Replacement MessageElement will be in the same name space as the replaced element.
         **/
        public void set( Object obj ) {
            if( origModCount != Message.this.getMessageModCount() ) {
                RuntimeException failure = new ConcurrentModificationException( Message.this + " concurrently modified. Iterator was made at mod " + origModCount );
                
                if (LOG.isEnabledFor(Level.ERROR)) {
                    LOG.error( Message.this + " concurrently modified. iterator mod=" + origModCount + " current mod=" + Message.this.getMessageModCount() + "\n" + getMessageModHistory(), failure );
                }
                
                throw failure;
            }
            
            if( !(obj instanceof MessageElement) ) {
                throw new IllegalStateException( "replacement must be a MessageElement" );
            }
            
            if( null == current ) {
                throw new IllegalStateException( "no current element, call next() or previous()" );
            }
            
            ListIterator elsPosition = Message.this.elements.listIterator();
            ListIterator nsPosition = ((List)( namespaces.get(current.namespace))).listIterator();
            
            int currentPrevious = list.previousIndex();
            
            // restart this iterator
            while( list.previousIndex() >= 0 ) {
                list.previous();
            }
            
            // readvance to the current position, but track in ns list and master list
            while( list.previousIndex() < currentPrevious ) {
                element anElement = (element) list.next();
                
                try {
                    // advance to the same element in the master list.
                    element anElsElement;
                    
                    do {
                        anElsElement = (element) elsPosition.next();
                    } while( anElement != anElsElement );
                    
                    // advance to the same element in the ns list.
                    MessageElement anNsElement;
                    
                    if( current.namespace.equals( anElement.namespace ) ) {
                        do {
                            anNsElement = (MessageElement) nsPosition.next();
                        } while( anElement.element != anNsElement );
                    }
                } catch ( NoSuchElementException ranOut ) {
                    RuntimeException failure = new ConcurrentModificationException( Message.this + " concurrently modified. Iterator was made at mod " + origModCount );
                    
                    if (LOG.isEnabledFor(Level.ERROR)) {
                       LOG.error( Message.this + " concurrently modified. iterator mod=" + origModCount + " current mod=" + Message.this.getMessageModCount() + "\n" + getMessageModHistory(), failure );
                    }
                    
                    throw failure;
                }
            }
            
            Message.element newCurrent = new Message.element( current.namespace, (MessageElement) obj );
            elsPosition.set( newCurrent );
            nsPosition.set( obj );
            list.set( newCurrent );
            origModCount = Message.this.incMessageModCount();
            if (LOG.isEnabledFor(Level.DEBUG)) {
                LOG.debug("Replaced " + current.namespace + "::" + current.element.getElementName() + "/" + current.element.getClass().getName() + "@" + current.element.hashCode() +
                " with " + newCurrent.namespace + "::" + newCurrent.element.getElementName() + "/" + newCurrent.element.getClass().getName() + "@" + newCurrent.element.hashCode() + " in " +  Message.this );
            }
            current = newCurrent;
        }
        
        /**
         *  return the namespace of the current element.
         *
         *  @return String containing the name space of the current element.
         **/
        public String getNamespace() {
            if( null == current ) {
                throw new IllegalStateException( "no current element, call next() or previous()" );
            }
            
            return current.namespace;
        }
    }
    
    /**
     *  holds an element and its namespace
     **/
    protected static class element {
        String namespace;
        
        MessageElement element;
        
        element( String namespace, MessageElement element ) {
            this.namespace = namespace;
            this.element = element;
        }
    }
    
    /**
     *  Returns the next message number in sequence.
     *
     *  @return the next message number in sequence.
     **/
    protected static int getNextMessageNumber() {
        synchronized( Message.class ) {
            return messagenumber++;
        }
    }
    
    /**
     *  Standard Constructor for messages. The default namespace will be the
     *  empty string ("")
     **/
    public Message() {
        this( "" );
        
        if( GLOBAL_TRACKING_ELEMENT ) {
            UUID tracking = UUIDFactory.newSeqUUID();
            
            MessageElement trackingElement = new StringMessageElement( "Tracking UUID", tracking.toString(), null );            

            addMessageElement( "jxta", trackingElement );
        }
    }
    
    /**
     *  Standard Constructor for messages.
     *
     *  @param defaultNamespace the namespace which is assumed when calls are
     *  made that don't include a namespace specification.
     **/
    protected Message(String defaultNamespace) {
        this.defaultNamespace = defaultNamespace;
        
        lineage.add( new Integer( getNextMessageNumber() ) );
        
        if ( LOG_MODIFICATIONS ) {
            modHistory = new ArrayList();
            incMessageModCount();
        }
    }
    
    /**
     *  {@inheritDoc}
     *
     * <p/> Duplicates the Message. The returned duplicate is a real copy. It may
     * be freely modified without causing change to the originally cloned
     * message.
     *
     * @return Message a Message that is a copy of the original message
     **/
    public Object clone() {
        Message clone = new Message( getDefaultNamespace() );
        
        clone.lineage.addAll( lineage );
        clone.elements.addAll( elements );
        
        Iterator eachNamespace = namespaces.keySet().iterator();
        
        while( eachNamespace.hasNext() ) {
            String aNamespace = (String) eachNamespace.next();
            
            List namespaceElements = (List) namespaces.get( aNamespace );
            
            List newNamespaceElements = new ArrayList( namespaceElements.size() );
            newNamespaceElements.addAll( namespaceElements );
            clone.namespaces.put( aNamespace, newNamespaceElements );
        }
        
        if (LOG.isEnabledFor(Level.DEBUG)) {
            LOG.debug("Created clone " + clone + " of " + this );
        }
        
        return clone;
    }
    
    /**
     *  {@inheritDoc}
     *
     *  <p/> Compare this Message against another. Returns true if all of the
     *  elements are identical and in the same order. Message properties
     *  (setProperty/getProperty) are not considered in the calculation.
     *
     *  @param target The  to compare against.
     *  @return boolean true if the elements are identical.
     **/
    public boolean equals( Object target ) {
        if( this == target ) {
            return true;
        }
        
        if( target instanceof Message ) {
            Message likeMe = (Message) target;
            
            ElementIterator myElements = getMessageElements();
            ElementIterator itsElements = likeMe.getMessageElements();
            
            while( myElements.hasNext() ) {
                if( !itsElements.hasNext() ) {
                    return false; // it has fewer than i do.
                }
                
                MessageElement mine = (MessageElement) myElements.next();
                MessageElement its = (MessageElement) itsElements.next();
                
                if( !myElements.getNamespace().equals( itsElements.getNamespace()) ) {
                    return false; // elements not in the same namespace
                }
                
                if( !mine.equals( its ) ) {
                    return false;       // content didnt match
                }
            }
            
            return ( !itsElements.hasNext() ); // ran out at the same time?
        }
        
        return false; // not a message
    }
    
    /**
     *  {@inheritDoc}
     **/
    public int hashCode() {
        int result = 0;
        Iterator eachElement = getMessageElements();
        
        while( eachElement.hasNext() ) {
            MessageElement anElement = (MessageElement) eachElement.next();
            
            result += anElement.hashCode();
            result *= 6037; // a prime
        }
        
        if( 0 == result  ) {
            result = 1;
        }
        
        return result;
    }
    
    /**
     *  {@inheritDoc}
     *
     *  <p/> Displays the lineage of the message including its own message number.
     *  This is useful primarily for debugging purposes.
     **/
    public String toString() {
        StringBuffer toString = new StringBuffer( 128 );
        
        toString.append( getClass().getName() );
        toString.append( '@' );
        toString.append( super.hashCode() );
        toString.append( '(' );
        toString.append( modCount );
        toString.append( "){" );