如何在不設置新實例類的情況下將XML文件顯示爲XML數據？

Question

我有一個XML文件，並希望將其顯示爲XML不是字符串，但我無法使用JAXB unmarshaller，因爲我沒有從一個類結構創建它，我爲該類創建了一個類，併爲類持有對象，以獲得該XML形式：

<?xml version="1.0" encoding="UTF-8" standalone="no"?> 
<XmlSource> 
<XmlConf> 
    <hostName>weather.yahooapis.com</hostName> 
    <parameters> 
     <entry> 
      <key>w</key> 
      <value>2502265</value> 
     </entry> 
    </parameters> 
    <URLPath>/forecastrss</URLPath> 
    <urlProtocol>http</urlProtocol> 
</XmlConf> 
<XmlConf> 
    <hostName>weather.yahooapis.com</hostName> 
    <parameters> 
     <entry> 
      <key>w</key> 
      <value>2502265</value> 
     </entry> 
    </parameters> 
    <URLPath>/forecastrss</URLPath> 
    <urlProtocol>http</urlProtocol> 
</XmlConf> 
<XmlConf> 
    <hostName>weather.yahooapis.com</hostName> 
    <parameters> 
     <entry> 
      <key>w</key> 
      <value>2502265</value> 
     </entry> 
    </parameters> 
    <URLPath>/forecastrss</URLPath> 
    <urlProtocol>http</urlProtocol> 
</XmlConf> 
</XmlSource> 

所以，我用下面的方法編組：

public void add(String fileName) throws IOException, JAXBException, 
      ParserConfigurationException, SAXException, TransformerException { 

       XmlConf object; 
     this.fileName = fileName; 
     File temp = new File(tempName); 
     JAXBContext jaxbContext = JAXBContext.newInstance(XmlConfList.class); 
     Marshaller jaxbMarshaller = jaxbContext.createMarshaller(); 

     jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); 

     File source = new File(fileName); 
     if (source.exists()) { 

      jaxbMarshaller.marshal(object, temp); 
      MergeXml merge = new MergeXml(); 
      merge.mergeXML(true, fileName, tempName, mainTag); 
     } else { 
      XmlStructure struct = new XmlStructure(); 
      jaxbMarshaller.marshal(struct, source); 
      jaxbMarshaller.marshal(object, temp); 
      MergeXml merge = new MergeXml(); 
      merge.mergeXML(true, fileName, tempName, mainTag); 
     } 
     temp.delete(); 
    } 

，並使用這個類來合併兩個XML結構：

public class MergeXml { 

    private static final String YES = "yes"; 
    private static final String generalTag = "*"; 

    /** 
    * This method used to merge XML old and new files together 
    * 
    * @param condition 
    * @throws ParserConfigurationException 
    * @throws SAXException 
    * @throws IOException 
    * @throws TransformerException 
    */ 
    public void mergeXML(boolean condition, String fileName, String tempName, String mainTag) 
      throws ParserConfigurationException, SAXException, IOException, 
      TransformerException { 

     DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); 
     DocumentBuilder db = null; 
     Document doc = null; 
     Document doc2 = null; 

     db = dbf.newDocumentBuilder(); 
     doc = db.parse(new File(fileName)); 
     doc2 = db.parse(new File(tempName)); 

     NodeList elements = doc.getElementsByTagName(mainTag); 

     if (condition == true) { 
      NodeList nodeList = doc2.getElementsByTagName(generalTag); 

      for (int i = 0; i < nodeList.getLength(); i++) { 

       Node node = nodeList.item(i); 
       Node childNode = doc.adoptNode(node); 

       elements.item(0).appendChild(childNode); 
      } 

     } 

     TransformerFactory tFactory = TransformerFactory.newInstance(); 
     Transformer transformer = tFactory.newTransformer(); 
     transformer.setOutputProperty(OutputKeys.INDENT, YES); 

     DOMSource source = new DOMSource(doc); 
     StreamResult result = new StreamResult(new StringWriter()); 
     transformer.transform(source, result); 

     BufferedWriter output = new BufferedWriter(new FileWriter(fileName)); 
     String xmlOutput = result.getWriter().toString(); 
     output.write(xmlOutput); 
     output.close(); 

    } 
} 

那麼，我該怎麼去解組呢？我不能寫：

JAXBContext jaxbContext = JAXBContext.newInstance(something.class); 

因爲它沒有在我的情況下工作。

Answer 1

我建議你使用DOM Level 3 Load and Save (LS) API：org.w3c.dom.ls.LSSerializer。

該代碼從here中取出，未經測試。這個想法應該清楚。

DOMImplementation domImplementation = document.getImplementation(); 
    if (domImplementation.hasFeature("LS", "3.0") 
      && domImplementation.hasFeature("Core", "2.0")) { 
     DOMImplementationLS domImplementationLS = (DOMImplementationLS) domImplementation 
       .getFeature("LS", "3.0"); 
     LSSerializer lsSerializer = domImplementationLS 
       .createLSSerializer(); 
     DOMConfiguration domConfiguration = lsSerializer.getDomConfig(); 
     if (domConfiguration.canSetParameter("format-pretty-print", 
       Boolean.TRUE)) { 
      lsSerializer.getDomConfig().setParameter("format-pretty-print", 
        Boolean.TRUE); 
      LSOutput lsOutput = domImplementationLS.createLSOutput(); 
      lsOutput.setEncoding("UTF-8"); 
      StringWriter stringWriter = new StringWriter(); 
      lsOutput.setCharacterStream(stringWriter); 
      lsSerializer.write(document, lsOutput); 
      return stringWriter.toString(); 
     } else { 
      throw new RuntimeException(
        "DOMConfiguration 'format-pretty-print' parameter isn't settable."); 
     } 
    } else { 
     throw new RuntimeException(
       "DOM 3.0 LS and/or DOM 2.0 Core not supported."); 
    }