为什么我会得到“org.w3c.dom.DOMException：HIERARCHY_REQUEST_ERR”这里？ [英] Why I get "org.w3c.dom.DOMException: HIERARCHY_REQUEST_ERR" Here?

问题描述

完全异常堆栈：

 线程main中的异常org.w3c.dom.DOMException：HIERARCHY_REQUEST_ERR：在不允许的情况下插入节点。 
 at org.apache.xerces.dom.CoreDocumentImpl.insertBefore（Unknown Source）
 at org.apache.xerces.dom.NodeImpl.appendChild（Unknown Source）
 at com.enniu.crawler .core.saxon.main（saxon.java:39）
 at sun.reflect.NativeMethodAccessorImpl.invoke0（Native Method）
 at sun.reflect.NativeMethodAccessorImpl.invoke（NativeMethodAccessorImpl.java:62）
 at sun.reflect.DelegatingMethodAccessorImpl.invoke（DelegatingMethodAccessorImpl.java:43）$ b $ at java.lang.reflect.Method.invoke（Method.java:497）
 at com.intellij.rt.execution .application.AppMain.main（AppMain.java:140）
  

我的代码：

  public class saxon {
 
 public static void main（String args []）throws IOException，SAXException，ParserConfigurationException，XPathFactoryConfigurationException， XPathExpressionException {
 
 DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance（）; 
 domFactory.setNamespaceAware（true）; 
 DocumentBuilder builder = null; 
 builder = domFactory.newDocumentBuilder（）; 
 Document doc = builder.parse（test.html）; 
 Document newDoc = builder.newDocument（）; 
 XPathFactory xpf = XPathFactoryImpl.newInstance（XPathConstants.DOM_OBJECT_MODEL）; 
 XPath xPath = xpf.newXPath（）; 
 XPathExpression compile = xPath.compile（// div [not（contains（class，'sss'））]）; 
 Object result = compile.evaluate（doc，XPathConstants.NODESET）; 
 NodeList节点=（NodeList）结果; 
 for（int i = 0; i< nodes.getLength（）; i ++）{
 Node copyNode = newDoc.importNode（nodes.item（i），true）; 
 newDoc.appendChild（copyNode）; //第39行
} 
 printXmlDocument（newDoc）; 
 
 
 public static void printXmlDocument（Document document）{
 DOMImplementationLS domImplementationLS = 
（DOMImplementationLS）document.getImplementation（）; 
 LSSerializer lsSerializer = 
 domImplementationLS.createLSSerializer（）; 
 String string = lsSerializer.writeToString（document）; 
 System.out.println（string）; 
 
 
 $ / code $ / pre> 
 
 
 test.html  
 
 
 < table> 
< div> aa< / div> 
< div class =sss> ss< / div> 
< div> dd< / div> 
< / table> 
  
 
 
解决方案
因为一个有效的http文件不能有两个根。我的代码尝试生成如下文档： 
 
 
 < div> aa< / div> 
< div> dd< / div> 
  
文档中有两个根，因此得到异常。  
Full exception stack: 
Exception in thread "main" org.w3c.dom.DOMException: HIERARCHY_REQUEST_ERR: An attempt was made to insert a node where it is not permitted. 
    at org.apache.xerces.dom.CoreDocumentImpl.insertBefore(Unknown Source)
    at org.apache.xerces.dom.NodeImpl.appendChild(Unknown Source)
    at com.enniu.crawler.core.saxon.main(saxon.java:39)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)
My Code: 
public class saxon {

    public static void main(String args[]) throws IOException, SAXException, ParserConfigurationException, XPathFactoryConfigurationException, XPathExpressionException {

        DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
        domFactory.setNamespaceAware(true);
        DocumentBuilder builder = null;
        builder = domFactory.newDocumentBuilder();
        Document doc = builder.parse("test.html");
        Document newDoc = builder.newDocument();
        XPathFactory xpf = XPathFactoryImpl.newInstance(XPathConstants.DOM_OBJECT_MODEL);
        XPath xPath = xpf.newXPath();
        XPathExpression compile = xPath.compile("//div[not (contains(class, 'sss'))]");
        Object result = compile.evaluate(doc, XPathConstants.NODESET);
        NodeList nodes = (NodeList) result;
        for(int i = 0; i < nodes.getLength(); i++) {
            Node copyNode = newDoc.importNode(nodes.item(i), true);
            newDoc.appendChild(copyNode);// line 39
        }
        printXmlDocument(newDoc);
    }

    public static void printXmlDocument(Document document) {
        DOMImplementationLS domImplementationLS =
                (DOMImplementationLS) document.getImplementation();
        LSSerializer lsSerializer =
                domImplementationLS.createLSSerializer();
        String string = lsSerializer.writeToString(document);
        System.out.println(string);
    }
}
test.html
<table>
    <div>aa</div>
    <div class="sss">ss</div>
    <div>dd</div>
</table>

解决方案
Because a valid http document can't have two roots. My code attempt to generate document like this:
<div>aa</div>
<div>dd</div>
There are two roots in the document so get the exception. 

                        
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