java - XML 将节点值解析为字符串

Question

我的 xml 文件是这样的。我想像这样获取 value 节点文本内容。

<property regex=".*" xpath=".*">
     <value>
          127.0.0.1
     </value>
<property regex=".*" xpath=".*">
<value>

</value>
</property>

我想按照他们在文件中指定的顺序获取文本。这是我的 Java 代码。

Document doc = parseDocument("properties.xml");
NodeList properties = doc.getElementsByTagName("property");
for( int i = 0 , len = properties.getLength() ; i < len ; i++) {
     Element property = (Element)properties.item(i);
     //How can i proceed further .
}

预期输出:

 Node 1 : 127.0.0.1

请提出您的看法。

Answer 1

以下方法查找所有property文档中的元素并收集所有 value那些名为 value 的元素的子元素不使用 XPath。

  private static List<Element> getValueElements(Document document) {
    List<Element> result = new ArrayList<Element>();
    NodeList propertyElements = document.getElementsByTagName("property");
    for (int i = 0, ilen = propertyElements.getLength(); i < ilen; i++) {
      Node propertyNode = propertyElements.item(i);
      if (!(propertyNode instanceof Element))
        continue;

      NodeList children = ((Element) propertyNode).getChildNodes();
      for (int j = 0, jlen = children.getLength(); j < jlen; j++) {
        Node child = children.item(j);
        if (!(child instanceof Element) || !"value".equals(child.getNodeName()))
          continue;

        result.add((Element) child);
      }
    }
    return result;
  }

但是您可以使用 XPath 表达式 //property/value 以更优雅的方式完成相同的操作:

private static List<Element> getValueElementsUsingXpath(Document document) throws XPathExpressionException {
  XPath xpath = XPathFactory.newInstance().newXPath();
  // XPath Query for showing all nodes value
  XPathExpression expr = xpath.compile("//property/value");
  Object xpathResult = expr.evaluate(document, XPathConstants.NODESET);

  List<Element> result = new ArrayList<Element>();
  NodeList nodes = (NodeList) xpathResult;
  for (int i = 0; i < nodes.getLength(); i++) {
    Node valueNode = nodes.item(i);
    if (!(valueNode instanceof Element)) continue;
    result.add((Element) valueNode);
  }

  return result;
}

你可以像这样使用上面的方法:

  public static void main(String[] args) throws Exception {
    Document doc = parseDocument("properties.xml");
    List<Element> valueElements = getValueElements(doc);  // or getValueElementsUsingXpath(doc)

    int nodeNumber = 0;
    for (Element element : valueElements) {
      nodeNumber++;
      System.out.println("Node " + nodeNumber + ": " + formatValueElement(element));
    }
  }

  private static String formatValueElement(Element element) {
    StringBuffer result = new StringBuffer();

    boolean first = true;
    NodeList children = ((Element) element).getChildNodes();
    for (int i = 0, len = children.getLength(); i < len; i++) {
      Node child = children.item(i);

      String childText = null;
      switch (child.getNodeType()) {
      case Node.CDATA_SECTION_NODE:
      case Node.TEXT_NODE:
        childText = child.getTextContent().trim();
      }

      if (childText == null || childText.isEmpty()) {
        continue;
      }

      if (first)
        first = false;
      else
        result.append(" ");

      result.append(childText);
    }

    return result.toString();
  }

我使用以下两个 XML 输入对其进行了测试，因为您的 XML 缺少结束符 </property>标签。

这是第一个(我添加了额外的元素，以表明找不到它们):

  <rootNode>
  <property regex=".*" xpath=".*">
       <value>
            127.0.0.1
       </value>
       <anythingElse>Text here</anythingElse>
  </property>
  <anythingElse>Text here</anythingElse>
  <property regex=".*" xpath=".*">
  <value>
       val <![CDATA[
       <Valve className="org.tomcat.AccessLogValve" exclude="PASSWORD,pwd,pWord,ticket" enabled="true" serviceName="zohocrm" logDir="../logs" fileName="access" format="URI,&quot;PARAM&quot;,&quot;REFERRER&quot;,TIME_TAKEN,BYTES_OUT,STATUS,TIMESTAMP,METHOD,SESSION_ID,REMOTE_IP,&quot;INTERNAL_IP&quot;,&quot;USER_AGENT&quot;,PROTOCOL,SERVER_NAME,SERVER_PORT,BYTES_IN,ZUID,TICKET_DIGEST,THREAD_ID,REQ_ID"/>
       ]]> test
  </value>
  </property>
  </rootNode>

第二个有嵌套的属性元素(我在末尾添加了缺少的元素):

  <property regex=".*" xpath=".*">
      <value>
          127.0.0.1
      </value>
      <property regex=".*" xpath=".*">
      <value>
          val <![CDATA[
          <Valve className="org.tomcat.AccessLogValve" exclude="PASSWORD,pwd,pWord,ticket" enabled="true" serviceName="zohocrm" logDir="../logs" fileName="access" format="URI,&quot;PARAM&quot;,&quot;REFERRER&quot;,TIME_TAKEN,BYTES_OUT,STATUS,TIMESTAMP,METHOD,SESSION_ID,REMOTE_IP,&quot;INTERNAL_IP&quot;,&quot;USER_AGENT&quot;,PROTOCOL,SERVER_NAME,SERVER_PORT,BYTES_IN,ZUID,TICKET_DIGEST,THREAD_ID,REQ_ID"/>
          ]]> test
      </value>
      </property>
  </property>