java操作xml - dom4j

本文通过实现将一个XML中的所有id值由正数更新为负值为例，展示dom4j读取、遍历以及更新xml的操作。

一、样例说明:

以下xml中的id="-182655332",<tag k="id" v="-182655332"/>,<member type="Highway" role="road" ref="-159475967"/>,<nd ref="-1262293804"/>都是我们要操作的数据(由正数改为负数)。

<?xml version="1.0" encoding="utf-8"?>
<osmChange>
  <topoGroup>
    <create>
      <way id="-182655332" version="1" transactionLoc="POINT (112.85030896500966 28.385729770656106)" changeset="20013309">
        <tag k="changeset_id" v="20013309"/>
        <tag k="visible" v="t"/>
        <tag k="area_flag" v="0"/>
        <tag k="adcode"/
        <tag k="source"/>
        <tag k="version" v="1"/>
        <tag k="src_flag" v="0"/>
        <tag k="datatype" v="DetailSlope"/>
        <tag k="id" v="-182655332"/>
        <tag k="mesh" v="H49F044039"/>
        <tag k="timestamp" v="1535361977065"/>
        <tag k="reference" v="{&quot;all&quot;:&quot;4081898_3_6f286966b604472994c0a91a160a4e51&quot;}"/>
      </way>
      <relation id="-19585073" lat="28.38493004" lon="112.84922079500001" version="1" transactionLoc="POINT (112.84922079500001 28.38493004)" changeset="20013309">
        <member type="Highway" role="road" ref="-159475967"/>
        <member type="DetailSlope" role="ds" ref="-182655332"/>
        <tag k="changeset_id" v="20013309"/>
        <tag k="visible" v="t"/>
        <tag k="datatype" v="RelDetailSlope"/>
        <tag k="adcode"/>
        <tag k="id" v="-19585073"/>
        <tag k="version" v="1"/>
        <tag k="mesh" v="H49F044039"/>
        <tag k="timestamp" v="1535361977065"/>
        <tag k="reference" v="{&quot;all&quot;:&quot;4081898_3_6f286966b604472994c0a91a160a4e51&quot;}"/>
      </relation>
    </create>
    <modify/>
    <delete/>
  </topoGroup>
  <create>
    <way id="-159475967" version="2" transactionLoc="POINT (112.84922079500001 28.38493004)" changeset="20013309" operType="3">
        <nd ref="-1262293804"/>
        <nd ref="-1262293805"/>
        <tag k="slope_src" v="2"/>
        <tag k="updatetime" v="20180827172617"/>
        <tag k="verifytime" v="20180707162959"/>
        <tag k="updateuser" v="2"/>
        <tag k="id" v="-159475967"/>
        <tag k="datatype" v="Highway"/>
        <tag k="the_geom" v="LINESTRING (112.84837322 28.38593057, 112.85006837 28.38392951)"/>
        <tag k="reference" v="{&quot;all&quot;:&quot;4081898_3_6f286966b604472994c0a91a160a4e51&quot;}"/>
    </way>
  </create>
  <modify/>
  <delete/>
</osmChange>

二、代码实现

//处理XML, 将xml中所有id值由正数更新为负值
public String processDeltaXML(String mark_delta_xml) {
    //遍历delta xml
    Document document = getDocument(mark_delta_xml);
    Element rootElement = document.getRootElement();
    handleDeltaXML(rootElement);
    return document.asXML();
}

//读取xml串转换成xml对象
private Document getDocument(String xmlContent) {
Document docDeltaXml = null;
try {
    SAXReader reader = new SAXReader();
    reader.setEncoding("GBK");
    docDeltaXml = reader.read(new ByteArrayInputStream(xmlContent
            .getBytes("GBK")));
} catch (Exception e) {
    System.out.println("解析xml失败");
    e.printStackTrace();
}
    return docDeltaXml;
}

//循环遍历xml进行处理
private void handleDeltaXML(Element rootElement) {
   Map<String, List<Element>> operateElementList = new HashMap<>();
   getOperateElementMap(rootElement, operateElementList);

   Set<Map.Entry<String, List<Element>>> entrySet = operateElementList.entrySet();
   Iterator<Map.Entry<String, List<Element>>> iter = entrySet.iterator();
   while (iter.hasNext()){
       Map.Entry<String, List<Element>> entry = iter.next();
       if ("create".equals(entry.getKey())) {
           handleOperateElements_create(entry.getValue());
       }
   }
}

// 解析xml对象获取到element name为"create", "modify","delete"的子结点
private void getOperateElementMap(Element rootElement, Map<String, List<Element>> operateElementMap) {
    List<String> operNames = new ArrayList<String>(){
        {
            add("create");
            add("modify");
            add("delete");
        }
    };

    List<Element> rootElementsList = rootElement.elements();
    for (Element element : rootElementsList) {
        if (operNames.contains(element.getName())) {
            if (operateElementMap.containsKey(element.getName())) {
                operateElementMap.get(element.getName()).addAll(element.elements());
            }
            else
            {
                operateElementMap.put(element.getName(), new ArrayList<>(element.elements()));
            }
        }
        else
        {
            getOperateElementMap(element, operateElementMap);
        }
    }
}

//处理新增结点
private void handleOperateElements_create(List<Element> createElementList) {
    for (Element element : createElementList) {
        //修改element上的id属性
        Attribute attr_id = element.attribute("id");
        attr_id.setValue("-" + attr_id.getValue());

        for (Object element_tag : element.elements()) {
            //修改非tag结点的ref属性
            if (!"tag".equals(((Element) element_tag).getName())) {
                Attribute attr_member_ref = ((Element) element_tag).attribute("ref");
                attr_member_ref.setValue("-" + attr_member_ref.getValue());
            }
            //修改tag为id结点的v属性
            else
            {
                if ("id".equals(((Element) element_tag).attributeValue("k"))) {
                    Attribute attr_tag_id = ((Element) element_tag).attribute("v");
                    attr_tag_id.setValue("-" + attr_tag_id.getValue());
                }
            }
        }

        //修改tag为id结点的v属性
        //Attribute attr_tag_id = ((Element) element.selectObject("tag[@k='id']")).attribute("v");
        //attr_tag_id.setValue("-" + attr_tag_id.getValue());

    }
}