如何在 Java 中刪除 XML Dom 中的額外縮進

Question

我正在 java 中編寫一個方法，它將數據附加到以下 XML 文件中：

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<Esko>

    <Employees>
                      
    </Employees>

</Esko>

在這里，我想將員工數據附加到這個員工標簽上，就像這樣。

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<MyOrg>
 

<Employees>
                              

    <Employee>
        <Name>gaurav kumar </Name>
        <Designation>SSSSS</Designation>
    </Employee>
    <Employee>
        <Name>gaurav kumar </Name>
        <Designation>SSSSS</Designation>
    </Employee>
    <Employee>
        <Name>gaurav</Name>
        <Designation>singh</Designation>
    </Employee>
</Employees>

</MyOrg>

為此，我正在使用此代碼：

public void saveToXML(String xml) {
    Document dom;
    NodeList employees = null;
    Node eRoot = null;
    // instance of a DocumentBuilderFactory
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    try {
        // use factory to get an instance of document builder
        DocumentBuilder db = dbf.newDocumentBuilder();
        // create instance of DOM
        dom = db.parse(xml);
     
        // create the root element
      //  Element rootEle = dom.getElementByName("Esko");
      
        // create data elements and place them under root
        employees = dom.getElementsByTagName("Employees");
        System.out.println(employees.item(0));
        eRoot = employees.item(0);

        
        eRoot.appendChild(createEmployee(dom, nameField.getText(), designationField.getText()));
        
        

        try {

            Transformer tr = TransformerFactory.newInstance().newTransformer();
            tr.setOutputProperty(OutputKeys.INDENT, "yes");
            tr.setOutputProperty(OutputKeys.METHOD, "xml");
            tr.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
            tr.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");

            
            // send DOM to file
            tr.transform(new DOMSource(dom), 
                                 new StreamResult(new FileWriter(xml)));

        } catch (TransformerException te) {
            System.out.println(te.getMessage());
        } catch (IOException ioe) {
            System.out.println(ioe.getMessage());
        }
    } catch (ParserConfigurationException pce) {
        System.out.println("UsersXML: Error trying to instantiate DocumentBuilder " + pce);
    } catch (SAXException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    } catch (IOException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }
}

private Element createEmployee(Document dom, String name, String des)
{
    Element e = dom.createElement("Employee");
    Element eName = dom.createElement("Name");
    Element eDes = dom.createElement("Designation");
    
    //create name and designation as child tag of Employee tag
    e.appendChild(eName);
    e.appendChild(eDes);
    
    // name tag contain what is supplied by the user at name field
    eName.appendChild(dom.createTextNode(name));
    // designation tag contains the designation by the user
    eDes.appendChild(dom.createTextNode(des));
    return e;
}

但現在發生的情況是，每次我保存一名新員工時，都會像這樣向 XML 增加額外的縮進。

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<MyOrg>
        

<Employees>
                
    
    <Employee>
                    
        <Name>gaurav</Name>
                    
        <Designation>SDET</Designation>
                
    </Employee>
        
    <Employee>
        <Name>gaurav kumar</Name>
        <Designation>SDET2</Designation>
    </Employee>
</Employees>
    

</MyOrg>

我不確定它的原因，但它正在發生，因為我每次保存到 xml 時都設置縮進。 任何人都可以幫助我為什么會發生這種情況，以及如何在沒有這些額外縮進的情況下保存它。

Answer 1

可以使用以下輔助函數從 XML 文檔中刪除空格：

 public static void removeWhitespaces(Element element) {
    NodeList children = element.getChildNodes();
    for (int i = children.getLength() - 1; i >= 0; i--) {
        Node child = children.item(i);
        if (child instanceof Text
            && ((Text) child).getData().trim().isEmpty()) {
            element.removeChild(child);
        } else if (child instanceof Element) {
            removeWhitespaces((Element) child);
        }
    }
}

它可以被稱為removeWhitespaces(dom.getDocumentElement()); 在調用tr.transform()之前。