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我有一个 xml 包含 1000 个事件的日志，每个事件都有一个键，我的目标是当用户搜索事件键时，我应该向他显示具有此键的事件节点的 xml 并准备前一个和下一个兄弟姐妹。

xml结构如下：

<LOG>
   <EVENT_SET>
      <DOCGET system="T610_00" fingerPrint="NO_SIGNATURE">
         <event>
            <key>382</key>
            <date>2015-01-28T09:15:15.350+0000</date>
            <service>CORE</service>
            <class>APPLICATION</class>
         </event>
         <document>
            <docuri>getdocs:///DocMapCSDOCS.dPortal/1</docuri>
            <sign_info>
               <signature>VqtR9Gpny/MPE43/5o4hJXp8bR7gbsVUJqHlTI+VfztMSQecTpZwAQpxmorrdBJKvmn+h7eZzV1geVodkVECvOjQMRmRbnpT6mrpbiXxjDOsZsQRDNemTYUKETrQFIBRtXcjoP61une1LOsS5C749ehwbZ1jEaNH6fPjH4n+OH4=</signature>
            </sign_info>
         </document>
      </DOCGET>
      <DOCGET system="T610_00" fingerPrint="NO_SIGNATURE">
         <event>
            <key>383</key>
            <date>2015-01-28T09:15:18.310+0000</date>
            <service>CORE</service>
            <class>APPLICATION</class>
         </event>
         <document>
            <docuri>getdocs:///DocMapCSDOCS.dPortal/2</docuri>
            <sign_info>
               <signature>VqtR9Gpny/MPE43/5o4hJXp8bR7gbsVUJqHlTI+VfztMSQecTpZwAQpxmorrdBJKvmn+h7eZzV1geVodkVECvOjQMRmRbnpT6mrpbiXxjDOsZsQRDNemTYUKETrQFIBRtXcjoP61une1LOsS5C749ehwbZ1jEaNH6fPjH4n+OH4=</signature>
            </sign_info>
         </document>
      </DOCGET>
      .......
  </EVENT_SET>
</LOG>

到目前为止，我获取密钥节点的代码是：

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setNamespaceAware(false);
DocumentBuilder builder = factory.newDocumentBuilder();
//parsing the xml file
journaldoc = builder.parse(journalFile);
XPathFactory xpathfactory = XPathFactory.newInstance();
XPath xpath = xpathfactory.newXPath();

//xpath to search for the event having the key requated by the user
String sXpath = "//DOCGET[event/key='"+eventkey+"']";
XPathExpression expr = xpath.compile(sXpath);
Object result = expr.evaluate(journaldoc, XPathConstants.NODE);
Node eventnode = (Node) result;

//return to the user the xml part with root DOCGET, and having the key requested
Document document = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
Node copyNode = document.importNode(eventNode, true);
document.appendChild(copyNode);
DOMImplementationLS domImplementationLS = (DOMImplementationLS) document.getImplementation();
LSSerializer lsSerializer = domImplementationLS.createLSSerializer();
String xmlNode =  lsSerializer.writeToString(document);

现在我需要获取该节点的上一个和下一个兄弟节点并获取它们的键，以便将它们保存在 HashMap 中。

问题是在执行 eventnode.getPreviousSibling 和 eventnode.getNextSibling 时，我得到了损坏的信息，我无法获得这些事件的密钥。

有没有人有更好的主意来做到这一点？

谢谢你，卡琳

4

1 回答 1

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我认为您正在寻找 XPath 轴preceding-sibling和following-sibling. 这些选择同一级别的所有节点，所以如果你只想要下一个邻居，你需要添加一个谓词来选择第一个：following-sibling::*[1]。但是您只需要事件节点，并且事件节点不是直接的兄弟姐妹，而是<DOCGET>元素。因此，您需要从一个事件节点向上，找到下一个/上一个兄弟节点并再次向下。这归结为这个表达式：../preceding-sibling::*[1]/event在事件节点上进行评估。

您可以通过使用数据投影（披露：我隶属于该项目）对事件进行面向对象的访问来简化任务，但仍将 Java 代码结构与 XML 结构分离：

public class ReadEvents {

public interface Event {
    @XBRead("./key")
    String getKey();

    @XBRead("./date using yyyy-MM-dd'T'HH:mm:ss.SSSZ")
    Date getDate();

    @XBRead("../document/docuri")
    String getDocumentURI();

    @XBRead("../preceding-sibling::*[1]/event")
    Event getPreviousEvent();

    @XBRead("../following-sibling::*[1]/event")
    Event getNextEvent();
}

public static void main(String... args) {
    List<Event> allEvents = new XBProjector().io().url("res://log.xml").evalXPath("//event").asListOf(Event.class);
    for (Event event : allEvents) {
        System.out.print(event.getDate()+ ": Event " + event.getKey());
        if (event.getPreviousEvent() != null) {
            System.out.print(" previous event has key " + event.getPreviousEvent().getKey());
        }
        if (event.getNextEvent() != null) {
            System.out.print(" next event has key " + event.getNextEvent().getKey());
        }
        System.out.println();
    }
  }
}

对于您的示例，此程序打印出：

Wed Jan 28 10:15:15 CET 2015: Event 382 next event has key 383
Wed Jan 28 10:15:18 CET 2015: Event 383 previous event has key 382
于 2015-02-02T07:26:32.450 回答