Question

我正在使用一个函数，它接收两个DOM元素 - 来自不同文档的父元素和子元素。我导入子元素，转换它，然后将它附加到父元素。但是，以下代码中的最后一行是抛出一个dom异常：org.w3c.dom.DOMException：WRONG_DOCUMENT_ERR：节点用于与创建它的文档不同的文档中。

请参阅下面的代码：

    public void attachNodeToParent (Element parent, Element child) throws Exception {
        Document parent_doc = parent.getOwnerDocument();
        child = (Element)parent_doc.importNode(child, true);
// Imported child Element is shown below:
//      <node id="101">
//        <node id="102">
//          <node id="103" />
//        </node>
//        <node id="104">
//          <node id="103" />
//        </node>
//      </node>

        // convert child Element into String
        Source source = new DOMSource(child);
        StringWriter stringWriter = new StringWriter();
        Result result = new StreamResult(stringWriter);
        TransformerFactory factory = TransformerFactory.newInstance();
        Transformer transformer = factory.newTransformer();
        transformer.transform(source, result);
        String childXml = stringWriter.getBuffer().toString();


        // Recursively modify the id attributes of every node
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document doc = db.parse(new InputSource(new StringReader(childXml)));
        XPathFactory xpathFactory = XPathFactory.newInstance();
        XPath xpath = xpathFactory.newXPath();
        NodeList nodes = (NodeList) xpath.compile("//node[@id]").evaluate(doc, XPathConstants.NODESET);
        for (int nodeNumber = 0; nodeNumber < nodes.getLength(); ++nodeNumber) {
            final Element node = (Element) nodes.item(nodeNumber);
            final String nodeId = node.getAttribute("id");
            final String newNodeId = "prefix/" + nodeId;
            node.getAttributeNode("id").setValue(newNodeId);
        }


        final StringWriter writer = new StringWriter();
        transformer.transform(source, new StreamResult(writer));
        writer.flush();
        writer.close();
        String transformedChildXml = writer.toString();

        // Prase transformedChildXml String into XML
        dbf.setNamespaceAware(true);
        DocumentBuilder builder = dbf.newDocumentBuilder();
        Document document = builder.parse(new InputSource(new StringReader(transformedChildXml)));
        document.setXmlStandalone(false);
        child = document.getDocumentElement();

        // child Element is now transformed to:
//        <node id="prefix/101">
//          <node id="prefix/102">
//            <node id="prefix/103" />
//          </node>
//          <node id="prefix/104">
//            <node id="prefix/103" />
//          </node>
//        </node>

        // append transformed child Element to parent Element
        // Throws o rg.w3c.dom.DOMException: WRONG_DOCUMENT_ERR: 
        // A node is used in a different document than the one that created it.
        parent.appendChild(child); 
    }

Answer 1

简短的回答是倒数第二行的子元素属于由行

创建的文档

Document document = builder.parse(new InputSource(new StringReader(transformedChildXml)));

而不是父母的所有者文件。因此，您必须再次使用importNode将其传输到目标文档。

但不要这样做。您的代码有两个序列化为String并解析回Document循环，这是非常低效的，也不是必需的。一旦你在开始时调用了importNode，只需将id固定到位，然后将子节点附加到父节点。

转换和附加Dom节点

1 个答案: