Java XML How to - 使用 xpath 在 XML 文件中的節點列表中查找和添加/替換更多子項

Question

我有一個 xml 文件 (ToThis.xml)，我正在用數組變量更新它。 我正在使用 Xpath 更新到這個 xml 文件，但我只能更新第一個數組元素。 見下文 。

xml 文件 (ToThis.xml) 我得到了什么

<?xml version="1.0" encoding="UTF-8"?><map xmlns="http://www.w3.org/2005/xpath-functions">
    <string key="ankomstDato">2020-08-20</string>
    <array key="planlagtAntallPerUndergruppe">
       <map>
          <number key="antall">67</number>
          <string key="kode">SLAKTEGRIS</string>
       </map> 
    </array>   
 </map>

我想獲得的 xml 文件應該如下所示

<?xml version="1.0" encoding="UTF-8"?><map xmlns="http://www.w3.org/2005/xpath-functions">
    <string key="ankomstDato">2020-08-20</string>
    <array key="planlagtAntallPerUndergruppe">
       <map>
          <number key="antall">67</number>
          <string key="kode">SLAKTEGRIS</string>
       </map> 
       <map>
          <number key="antall">4</number>
          <string key="kode">UNGSAU</string>
     </map>
    </array>   
 </map>

下面是代碼的一部分，它讓我得到第一個結果。 注意（實際場景中的兩個數組變量不是硬編碼的，它們是動態分配的）

public void Write2XMLfile(){
    
            XPathFactory xpathFact = XPathFactory.newInstance();
        XPath xpath = xpathFact.newXPath();
    
        try {
    
            //
            String filepath = "E:/utils/Tothis.xml";
            //
    
            
            DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
            Document doc = docBuilder.parse(filepath);

            planlagtAntallPerUndergruppe_antall_value[0] = "67";                
            planlagtAntallPerUndergruppe_kode_value[0] = "SLAKTEGRIS";

            planlagtAntallPerUndergruppe_antall_value[1] = "4";                
            planlagtAntallPerUndergruppe_kode_value[1] = "UNGSAU";        
    
            //2.  planlagtAntallPerUndergruppe **************************
            System.out.println("\n This is second" );
            Node planlagtAntallPerUndergruppe = (Node) xpath.evaluate("/map/array[@key='planlagtAntallPerUndergruppe']/*", doc, XPathConstants.NODE);
            if(null != planlagtAntallPerUndergruppe) {
                NodeList nodeList = planlagtAntallPerUndergruppe.getChildNodes();
                for (int i = 0;null!=nodeList && i < nodeList.getLength(); i++) {
                    Node nod = nodeList.item(i);
                    if(nod.getNodeType() == Node.ELEMENT_NODE){
                        NodeList arrayElements_18 = (NodeList) xpath.evaluate("/map/array[@key='planlagtAntallPerUndergruppe']/*", doc, XPathConstants.NODESET);
                        //System.out.println("\n number of elements" + arrayElements_18.getLength());
                        for (int j = 0; j < arrayElements_18.getLength(); j++) {
                            //.  antall
                            Node antall = (Node) xpath.evaluate("(/map/array/map/number[@key='antall'])[1]", doc, XPathConstants.NODE);
                            antall.setTextContent(planlagtAntallPerUndergruppe_antall_value[j]);
                            // end antall
    
                            //.  kode
                            Node kode = (Node) xpath.evaluate("(/map/array/map/string[@key='kode'])[1]", doc, XPathConstants.NODE);
                            kode.setTextContent(planlagtAntallPerUndergruppe_kode_value[j]);
                            //System.out.println("\n\n antall: " + planlagtAntallPerUndergruppe_antall_value[j]);
    
                            // end kode                       
                        }                    
                    }
                         
                }
            }
    
            // end array planlagtAntallPerUndergruppe
            
    
            // write the content into xml file
            TransformerFactory transformerFactory = TransformerFactory.newInstance();
            Transformer transformer = transformerFactory.newTransformer();
            DOMSource source = new DOMSource(doc);
            StreamResult result = new StreamResult(new File(filepath));
            transformer.transform(source, result);
    
            System.out.println("Done Updating The Api_XML_Format.xml");
    
        } catch (ParserConfigurationException pce) {
            pce.printStackTrace();
        } catch (TransformerException tfe) {
            tfe.printStackTrace();
        } catch (IOException ioe) {
            ioe.printStackTrace();
        } catch (SAXException sae) {
       

     sae.printStackTrace();
    } catch (XPathExpressionException xee) {
        xee.printStackTrace();
    }

    
  }

Answer 1

Xpath 專門用於跟蹤/讀取 xml，但不能用於修改 xml。

因此，我將代碼從使用 XPath 更改為使用 DOM Parser。

try
            {
        DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
        DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
        Document doc = docBuilder.newDocument();
        // Map root element
        Element rootElement = doc.createElement("map");
        doc.appendChild(rootElement);
        //ROOT map
        
        //1. ankomstDato
        Element ankomstDato = doc.createElement("string");
        Attr attrType_ankomstDato = doc.createAttribute("key");
        attrType_ankomstDato.setValue("ankomstDato");
        ankomstDato.setAttributeNode(attrType_ankomstDato);
        ankomstDato.appendChild(doc.createTextNode(ankomstDato_value));
        rootElement.appendChild(ankomstDato);

        //. planlagtAntallPerUndergruppe
        // planlagtAntallPerUndergruppe element
        

        if (planlagtAntallPerUndergruppe_Count !=0){
            Element planlagtAntallPerUndergruppe = doc.createElement("array");
            rootElement.appendChild(planlagtAntallPerUndergruppe);

            Attr attr = doc.createAttribute("key");
            attr.setValue("planlagtAntallPerUndergruppe");
            planlagtAntallPerUndergruppe.setAttributeNode(attr);

            for (int i = 0; i < planlagtAntallPerUndergruppe_Count; i ++){
                //to add "map" element
                Element map1 = doc.createElement("map");
                planlagtAntallPerUndergruppe.appendChild(map1);


                    // antall element
                    Element antall = doc.createElement("number");
                    Attr attrType = doc.createAttribute("key");
                    attrType.setValue("antall");
                    antall.setAttributeNode(attrType);
                    antall.appendChild(doc.createTextNode(planlagtAntallPerUndergruppe_antall_value[i]));
                    map1.appendChild(antall);
                    
                    //kode element
                    Element kode = doc.createElement("string");
                    Attr attrType1 = doc.createAttribute("key");
                    attrType1.setValue("kode");
                    kode.setAttributeNode(attrType1);
                    kode.appendChild(doc.createTextNode(planlagtAntallPerUndergruppe_kode_value[i]));
                    map1.appendChild(kode);
            }
        }
        //end planlagtAntallPerUndergruppe

        
        // Write the content into XML file
        DOMSource source = new DOMSource(doc);
        StreamResult result = new StreamResult(new File("E:/utils/students-new.xml"));
        
        TransformerFactory transformerFactory = TransformerFactory.newInstance();
        Transformer transformer = transformerFactory.newTransformer();
        // Beautify the format of the resulted XML
        transformer.setOutputProperty(OutputKeys.INDENT, "yes");
        transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");
        transformer.transform(source, result);
         }
        catch(Exception ex)
          {
            ex.printStackTrace();
        }
    
      }

Answer 2

將收集的數組作為參數傳遞給Write2XMLfile方法

public void Write2XMLfile(String[] planlagtAntallPerUndergruppe_antall_value, String[] planlagtAntallPerUndergruppe_kode_value) {
   
   try {
       
         DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
         DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
         Document doc = dBuilder.newDocument();
         
         Element rootElement = doc.createElement("map");
         doc.appendChild(rootElement);

         Element mainString = doc.createElement("string");
         mainString.setAttribute("key", "ankomstDato");
         rootElement.appendChild(mainString).setTextContent("2020-08-20");
         
         
         Element array = doc.createElement("array");
         array.setAttribute("key", "planlagtAntallPerUndergruppe");
         rootElement.appendChild(array);
         

         if(planlagtAntallPerUndergruppe_antall_value.length>0){
             for (int i = 0; i < planlagtAntallPerUndergruppe_antall_value.length; i++) {
                Element map = doc.createElement("map");
                array.appendChild(map);
                
                Element number =  doc.createElement("number");
                number.setAttribute("key", "antall");
                map.appendChild(number).setTextContent(planlagtAntallPerUndergruppe_antall_value[i]);
                
                Element string =  doc.createElement("string");
                string.setAttribute("key", "kode");
                map.appendChild(string).setTextContent(planlagtAntallPerUndergruppe_kode_value[i]);
            }
         }

         TransformerFactory transformerFactory = TransformerFactory.newInstance();
         Transformer transformer = transformerFactory.newTransformer();
         transformer.setOutputProperty(OutputKeys.INDENT, "yes");
         transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
         DOMSource source = new DOMSource(doc);
         StreamResult output = new StreamResult(new File("output.xml"));
         transformer.transform(source, output);
         
      } catch (Exception e) {
         e.printStackTrace();
      }
}

輸出文件

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<map>
  <string key="ankomstDato">2020-08-20</string>
  <array key="planlagtAntallPerUndergruppe">
    <map>
      <number key="antall">67</number>
      <string key="kode">SLAKTEGRIS</string>
    </map>
    <map>
      <number key="antall">4</number>
      <string key="kode">UNGSAU</string>
    </map>
  </array>
</map>