xpathresultimpl.java

java1.6众多例子参考

		NodeIterator result = null;
		try {
			result = m_resultObj.nodeset();
		} catch (TransformerException te) {
			throw new XPathException(XPathException.TYPE_ERR,te.getMessage());
		}
        
        if (null == result) return null;
        
        Node node = result.nextNode();
         
        // Wrap "namespace node" in an XPathNamespace 
        if (isNamespaceNode(node)) {
            return new XPathNamespaceImpl(node);
        } else {
            return node;
        }        
	}

	/**
	 * @see org.w3c.dom.xpath.XPathResult#getInvalidIteratorState()
	 */
	public boolean getInvalidIteratorState() {
		return m_isInvalidIteratorState;
	}

	/**
	 * The number of nodes in the result snapshot. Valid values for 
     * snapshotItem indices are <code>0</code> to 
     * <code>snapshotLength-1</code> inclusive.
     * @exception XPathException
     *   TYPE_ERR: raised if <code>resultType</code> is not 
     *   <code>UNORDERED_NODE_SNAPSHOT_TYPE</code> or 
     *   <code>ORDERED_NODE_SNAPSHOT_TYPE</code>.
     * 
	 * @see org.w3c.dom.xpath.XPathResult#getSnapshotLength()
	 */
	public int getSnapshotLength() throws XPathException {
	
		if ((m_resultType != UNORDERED_NODE_SNAPSHOT_TYPE) &&
		    (m_resultType != ORDERED_NODE_SNAPSHOT_TYPE)) {
				String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_CANT_GET_SNAPSHOT_LENGTH, new Object[] {m_xpath.getPatternString(), getTypeString(m_resultType)});                        
				throw new XPathException(XPathException.TYPE_ERR,fmsg); 
//				"The method getSnapshotLength cannot be called on the XPathResult of XPath expression {0} because its XPathResultType is {1}.
	    }
			
		return m_list.getLength();
	}

	/**
	 * Iterates and returns the next node from the node set or 
     * <code>null</code>if there are no more nodes.
     * @return Returns the next node.
     * @exception XPathException
     *   TYPE_ERR: raised if <code>resultType</code> is not 
     *   <code>UNORDERED_NODE_ITERATOR_TYPE</code> or 
     *   <code>ORDERED_NODE_ITERATOR_TYPE</code>.
     * @exception DOMException
     *   INVALID_STATE_ERR: The document has been mutated since the result was 
     *   returned.
	 * @see org.w3c.dom.xpath.XPathResult#iterateNext()
	 */
	public Node iterateNext() throws XPathException, DOMException {
		if ((m_resultType != UNORDERED_NODE_ITERATOR_TYPE) &&
		    (m_resultType != ORDERED_NODE_ITERATOR_TYPE)) {
          String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_NON_ITERATOR_TYPE, new Object[] {m_xpath.getPatternString(), getTypeString(m_resultType)});                        
		  throw new XPathException(XPathException.TYPE_ERR, fmsg);  
//		  "The method iterateNext cannot be called on the XPathResult of XPath expression {0} because its XPathResultType is {1}. 
//		  This method applies only to types UNORDERED_NODE_ITERATOR_TYPE and ORDERED_NODE_ITERATOR_TYPE."},
	    }

		if (getInvalidIteratorState()) {
          String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_DOC_MUTATED, null);                        
		  throw new DOMException(DOMException.INVALID_STATE_ERR,fmsg);  // Document mutated since result was returned. Iterator is invalid.
		}			 

        Node node = m_iterator.nextNode();
        if(null == node)
        	removeEventListener(); // JIRA 1673
        // Wrap "namespace node" in an XPathNamespace 
        if (isNamespaceNode(node)) {
            return new XPathNamespaceImpl(node);
        } else {
            return node;
        }
	}

    /**
     * Returns the <code>index</code>th item in the snapshot collection. If 
     * <code>index</code> is greater than or equal to the number of nodes in 
     * the list, this method returns <code>null</code>. Unlike the iterator 
     * result, the snapshot does not become invalid, but may not correspond 
     * to the current document if it is mutated.
     * @param index Index into the snapshot collection.
     * @return The node at the <code>index</code>th position in the 
     *   <code>NodeList</code>, or <code>null</code> if that is not a valid 
     *   index.
     * @exception XPathException
     *   TYPE_ERR: raised if <code>resultType</code> is not 
     *   <code>UNORDERED_NODE_SNAPSHOT_TYPE</code> or 
     *   <code>ORDERED_NODE_SNAPSHOT_TYPE</code>.
     *
	 * @see org.w3c.dom.xpath.XPathResult#snapshotItem(int)
	 */
	public Node snapshotItem(int index) throws XPathException {
		
		if ((m_resultType != UNORDERED_NODE_SNAPSHOT_TYPE) &&
		    (m_resultType != ORDERED_NODE_SNAPSHOT_TYPE)) {
           String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_NON_SNAPSHOT_TYPE, new Object[] {m_xpath.getPatternString(), getTypeString(m_resultType)});                        
           throw new XPathException(XPathException.TYPE_ERR, fmsg); 
//		"The method snapshotItem cannot be called on the XPathResult of XPath expression {0} because its XPathResultType is {1}. 
//		This method applies only to types UNORDERED_NODE_SNAPSHOT_TYPE and ORDERED_NODE_SNAPSHOT_TYPE."},
	    }		
        
        Node node = m_list.item(index);
        
        // Wrap "namespace node" in an XPathNamespace 
        if (isNamespaceNode(node)) {
            return new XPathNamespaceImpl(node);
        } else {
            return node;
        }
	}

	
	/**
	 * Check if the specified type is one of the supported types.
	 * @param type The specified type
	 * 
	 * @return true If the specified type is supported; otherwise, returns false.
	 */
	static boolean isValidType( short type ) {
		switch (type) {
			case ANY_TYPE:
			case NUMBER_TYPE:
			case STRING_TYPE:
			case BOOLEAN_TYPE:
			case UNORDERED_NODE_ITERATOR_TYPE:
			case ORDERED_NODE_ITERATOR_TYPE:
			case UNORDERED_NODE_SNAPSHOT_TYPE:
			case ORDERED_NODE_SNAPSHOT_TYPE:
			case ANY_UNORDERED_NODE_TYPE:
			case FIRST_ORDERED_NODE_TYPE: return true;
			default: return false;
		}
	}

	/**
	 * @see org.w3c.dom.events.EventListener#handleEvent(Event)
	 */
	public void handleEvent(Event event) {
		
		if (event.getType().equals("DOMSubtreeModified")) {
			// invalidate the iterator
			m_isInvalidIteratorState = true;
			
			// deregister as a listener to reduce computational load
			removeEventListener();
		}
	}
    
  /**
   * Given a request type, return the equivalent string.
   * For diagnostic purposes.
   *
   * @return type string 
   */
  private String getTypeString(int type)
  {
     switch (type) {
      case ANY_TYPE: return "ANY_TYPE";
      case ANY_UNORDERED_NODE_TYPE: return "ANY_UNORDERED_NODE_TYPE";
      case BOOLEAN_TYPE: return "BOOLEAN";
      case FIRST_ORDERED_NODE_TYPE: return "FIRST_ORDERED_NODE_TYPE";
      case NUMBER_TYPE: return "NUMBER_TYPE";
      case ORDERED_NODE_ITERATOR_TYPE: return "ORDERED_NODE_ITERATOR_TYPE";
      case ORDERED_NODE_SNAPSHOT_TYPE: return "ORDERED_NODE_SNAPSHOT_TYPE";
      case STRING_TYPE: return "STRING_TYPE";
      case UNORDERED_NODE_ITERATOR_TYPE: return "UNORDERED_NODE_ITERATOR_TYPE";
      case UNORDERED_NODE_SNAPSHOT_TYPE: return "UNORDERED_NODE_SNAPSHOT_TYPE";
      default: return "#UNKNOWN";
    }
  }  
  
  /**
   * Given an XObject, determine the corresponding DOM XPath type
   * 
   * @return type string
   */
  private short getTypeFromXObject(XObject object) {
      switch (object.getType()) {
        case XObject.CLASS_BOOLEAN: return BOOLEAN_TYPE;
        case XObject.CLASS_NODESET: return UNORDERED_NODE_ITERATOR_TYPE; 
        case XObject.CLASS_NUMBER: return NUMBER_TYPE;
        case XObject.CLASS_STRING: return STRING_TYPE;
        // XPath 2.0 types                         
//          case XObject.CLASS_DATE: 
//          case XObject.CLASS_DATETIME:
//          case XObject.CLASS_DTDURATION:
//          case XObject.CLASS_GDAY:
//          case XObject.CLASS_GMONTH:
//          case XObject.CLASS_GMONTHDAY:
//          case XObject.CLASS_GYEAR:
//          case XObject.CLASS_GYEARMONTH: 
//          case XObject.CLASS_TIME:
//          case XObject.CLASS_YMDURATION: return STRING_TYPE; // treat all date types as strings?
      
        case XObject.CLASS_RTREEFRAG: return UNORDERED_NODE_ITERATOR_TYPE; 
        case XObject.CLASS_NULL: return ANY_TYPE; // throw exception ?
        default: return ANY_TYPE; // throw exception ?
    }     
    
  }  

/**
 * Given a node, determine if it is a namespace node.
 * 
 * @param node 
 * 
 * @return boolean Returns true if this is a namespace node; otherwise, returns false.
 */
  private boolean isNamespaceNode(Node node) {
    
     if ((null != node) && 
         (node.getNodeType() == Node.ATTRIBUTE_NODE) &&
         (node.getNodeName().startsWith("xmlns:") || node.getNodeName().equals("xmlns"))) {
        return true;   
     } else {
        return false;
     }
  }
  
/**
 * Add m_contextNode to Event Listner to listen for Mutations Events
 *
 */
  private void addEventListener(){
  	if(m_contextNode instanceof EventTarget)
		((EventTarget)m_contextNode).addEventListener("DOMSubtreeModified",this,true);
  	
  }
  

/**
 * Remove m_contextNode to Event Listner to listen for Mutations Events
 *
 */
private void removeEventListener(){
	if(m_contextNode instanceof EventTarget)
		((EventTarget)m_contextNode).removeEventListener("DOMSubtreeModified",this,true);
}
  
}