How to convert xml to java string list

Question

I have a xml string in java that I need to break up into smaller strings. For example, given the following:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?> 
    <employee id="111">    
        <firstName>Lokesh</firstName>    
        <lastName>Gupta</lastName>     
        <location>India</location>   
    </employee> 
    <employee id="222">    
        <firstName>Alex</firstName>    
        <lastName>Gussin</lastName>    
        <location>Russia</location>    
    </employee> 
    <employee id="333">    
        <firstName>David</firstName>    
        <lastName>Feezor</lastName>    
        <location>USA</location>    
    </employee>

How can I parse without any noticeable delimiters to obtain:

string1 = "<employee id="111">    <firstName>Lokesh</firstName>    <lastName>Gupta</lastName>    <location>India</location>   </employee>"
string2 = "<employee id="222">    <firstName>Alex</firstName>    <lastName>Gussin</lastName>    <location>Russia</location>    </employee>"
string3 = "<employee id="333">    <firstName>David</firstName>    <lastName>Feezor</lastName>    <location>USA</location>    </employee>"

Any ideas are appreciated. Thanks!

Use JAXB to parse XML into Java object model. Then create anything you want out of it. — Tarlog
– Tarlog, Commented Feb 24, 2020 at 23:53
Underscore-java can read xml to a map. U.fromXmlMap(xml) will help. — Valentyn Kolesnikov
– Valentyn Kolesnikov, Commented Feb 25, 2020 at 0:40
Are you sure you want strings? You have to parse the XML document once to get separate employee elements; why not just keep the parser, rather than go to the trouble of creating strings and parsing each string a second time? — VGR
– VGR, Commented Feb 25, 2020 at 3:27

Andreas · Accepted Answer · 2020-02-25 00:43:01Z

You can parse the XML into DOM, iterate the child nodes of the root element (once you add one to the XML), and render each element as XML.

String xml = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?> \r\n" + 
             "<employee id=\"111\">    \r\n" + 
             "    <firstName>Lokesh</firstName>    \r\n" + 
             "    <lastName>Gupta</lastName>     \r\n" + 
             "    <location>India</location>   \r\n" + 
             "</employee> \r\n" + 
             "<employee id=\"222\">    \r\n" + 
             "    <firstName>Alex</firstName>    \r\n" + 
             "    <lastName>Gussin</lastName>    \r\n" + 
             "    <location>Russia</location>    \r\n" + 
             "</employee> \r\n" + 
             "<employee id=\"333\">    \r\n" + 
             "    <firstName>David</firstName>    \r\n" + 
             "    <lastName>Feezor</lastName>    \r\n" + 
             "    <location>USA</location>    \r\n" + 
             "</employee>";

// Add missing root element
xml = xml.replaceAll("^(<\\?xml.*?\\?>)?", "$1<X>") + "</X>";

// Prepare parser
DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder domBuilder = domFactory.newDocumentBuilder();
Document document = domBuilder.parse(new InputSource(new StringReader(xml)));

// Prepare renderer
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

// Iterate top-level elements and render them to individual strings
List<String> list = new ArrayList<>();
for (Node node = document.getDocumentElement().getFirstChild(); node != null; node = node.getNextSibling()) {
    if (node.getNodeType() == Node.ELEMENT_NODE) {
        StringWriter buf = new StringWriter();
        transformer.transform(new DOMSource(node), new StreamResult(buf));
        String elementXml = buf.toString();
        elementXml = elementXml.replaceAll("\\R", " ").trim(); // Eliminate line separators
        list.add(elementXml);
    }
}

// Print the result
for (String s : list)
    System.out.printf("'%s'%n", s);

Output

'<employee id="111">         <firstName>Lokesh</firstName>         <lastName>Gupta</lastName>          <location>India</location>    </employee>'
'<employee id="222">         <firstName>Alex</firstName>         <lastName>Gussin</lastName>         <location>Russia</location>     </employee>'
'<employee id="333">         <firstName>David</firstName>         <lastName>Feezor</lastName>         <location>USA</location>     </employee>'

Hmmh, whilst this does answer the particular use case, it seems to be just manipulating the DOM (in one particular case). I would rather reference to something like:en.wikipedia.org/wiki/XPath this allows a more generic solution.

ykaganovich · Accepted Answer · 2020-02-25 03:28:53Z

You can do it using StAX:

private ArrayList <String> getEmployees(String input) throws XMLStreamException {
    ArrayList <String> employees = new ArrayList <>();

    XMLEventReader xmlEventReader = XMLInputFactory.newInstance().createXMLEventReader(new StringReader(input));
    XMLOutputFactory xmlOutputFactory = XMLOutputFactory.newInstance();

    XMLEventWriter xmlEventWriter = null;
    StringWriter sw = null;
    while (xmlEventReader.hasNext()) {
        XMLEvent xmlEvent = xmlEventReader.nextEvent();
        if(xmlEvent.isStartElement() && xmlEvent.asStartElement().getName().getLocalPart().equals("employee"))  {
            sw = new StringWriter();
            xmlEventWriter = xmlOutputFactory.createXMLEventWriter(sw);
        }

        if(xmlEventWriter != null) {
            if(xmlEvent.isCharacters() && xmlEvent.asCharacters().isWhiteSpace()) {
                continue;
            }

            xmlEventWriter.add(xmlEvent);
        }

        if(xmlEvent.isEndElement() && xmlEvent.asEndElement().getName().getLocalPart().equals("employee")) {
            xmlEventWriter.close();
            employees.add(sw.toString());
            xmlEventWriter = null;
            sw = null;
        }
    }

    return employees;
}

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