相关疑难解决方法(0)

我想循环遍历每个XML打印的所有元素.我的问题是我在staff1标签后不断获得空指针异常,即john 465456433 gmail1 area1 city1

这是我的Java代码,用于打印xml文件中的所有元素:

File fXmlFile = new File("file.xml");
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(fXmlFile);

doc.getDocumentElement().normalize();

System.out.println("Root element :" + doc.getDocumentElement().getNodeName());

NodeList nList = doc.getElementsByTagName("*");

System.out.println("----------------------------");

Node n=null;
Element eElement=null;

for (int i = 0; i < nList.getLength(); i++) {           
  System.out.println(nList.getLength());     
  n= nList.item(i);                            
  System.out.println("\nCurrent Element :" + n.getNodeName());


  if (n.getNodeType() == Node.ELEMENT_NODE) {
    eElement = (Element) n.getChildNodes();
    System.out.println("\nCurrent Element :" + n.getNodeName());
    name = eElement.getElementsByTagName("name").item(i).getTextContent(); //here throws null pointer …

我正在尝试使用特定的命名空间构建XML文档.我想要生成的最终文档看起来像这样:

<m:documentObject xmlns:m="http://www.myschema.com">
    <sender>token</sender>
    <receiver>token</receiver>
    <payload>token</payload>
</m:documentObject>

这是我到目前为止所拥有的.

Document document = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
Element requestElement = document.createElementNS("http://www.myschema.com", "documentObject");

document.appendChild(requestElement);

Element sender = document.createElement("sender");
requestElement.appendChild(sender);     
Text senderText = document.createTextNode("Xmlsender");
sender.appendChild(senderText); 

Element receiver = document.createElement("receiver");
requestElement.appendChild(receiver);       
Text receiverText = document.createTextNode("Xmlreceiver");
receiver.appendChild(receiverText); 

Element payload = document.createElement("payload");
requestElement.appendChild(payload);        
Text payloadText = document.createTextNode("Xmlpayload");
payload.appendChild(payloadText);   

StringWriter sw = new StringWriter();
StreamResult result = new StreamResult(sw);

DOMSource source = new DOMSource(requestElement);

TransformerFactory tf = TransformerFactory.newInstance();
Transformer transformer = tf.newTransformer();
transformer.setOutputProperty(OutputKeys.ENCODING, "utf-8"); 
transformer.transform(source, result);

String xmlString = sw.toString();
System.out.println(xmlString) …

我正在通过Java创建多个XML文件，到目前为止一切正常，但是现在尝试创建带有命名空间前缀节点的文件时遇到了问题，例如，<tns:node> ... </tns:node>使用已经重构的代码版本适用于没有名称空间的普通xml文件。

被抛出的错误是：

org.w3c.dom.DOMException: INVALID_CHARACTER_ERR: Ungültiges XML-Zeichen angegeben. 

抱歉，德国人说“指定了无效的XML符号”。

发生错误的代码行：

Element mainRootElement = doc.createElement("tns:cmds xmlns:tns=\"http://abc.de/x/y/z\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:schemaLocation=\"http://abc.de/x/y/z xyzschema.xsd\"");

为了消除错误导致转义较长的字符串或那些行中的某些内容的可能性，我也尝试仅使用Element mainRootElement = doc.createElement("tns:cmds");，但这会导致相同的错误。

这就是为什么我认为它与名称空间声明（即:用来完成名称空间）有关，因为这是我在该字符串中想到的唯一“无效”字符。

谁能确认这是问题的根源？如果是这样，是否有一个简单的解决方案？Java DOM可以完全使用命名空间标记吗？

编辑：整个方法供参考

private void generateScriptXML()
    {
        DocumentBuilderFactory icFactory = DocumentBuilderFactory.newInstance();
        DocumentBuilder icBuilder;
        try
        {
            icBuilder = icFactory.newDocumentBuilder();
            Document doc = icBuilder.newDocument();

            Element mainRootElement = doc.createElement("tns:cmds xmlns:tns=\"http://abc.de/x/y/z\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:schemaLocation=\"http://abc.de/x/y/z xyzschema.xsd\"");

            doc.appendChild(mainRootElement);
            mainRootElement.appendChild(getAttributes(doc,"xxx", "yyy", "zzz"));
            mainRootElement.appendChild(getAttributes(doc,"aaa", "bbb", "ccc"));
            mainRootElement.appendChild(getAttributes(doc,"ddd", "eee", "fff"));
            ...
            ...

            Transformer transformer = TransformerFactory.newInstance().newTransformer();
            transformer.setOutputProperty(OutputKeys.INDENT, "yes");
            DOMSource source …

I need to set prefix of the element in my xml. I need to print the xml in the format below:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<cars xmlns:dcterms="http://purl.org/dc/terms/" xmlns:msxsl="urn:schemas-microsoft-com:xslt">
<supercars company="Ferrari">
<dcterms:carname type="formula one">Ferrari 101</dcterms:carname>
<msxsl:carname type="sports">Ferrari 202</msxsl:carname>
</supercars>
</cars>

However, I am not able to add the prefix in my XML. What I am getting is this.

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<cars xmlns:dcterms="http://purl.org/dc/terms/" xmlns:msxsl="urn:schemas-microsoft-com:xslt">
<supercars company="Ferrari">
<carname type="formula one">Ferrari 101</carname>
<carname type="sports">Ferrari 202</carname>
</supercars>
</cars>

Following is my Java Code: …