Create instance of XML document using XSD in Java

Question

I am looking for a Java library that can take an XSD schema and create a sample XML document that can then be manipulated. In my simple example i am given an XML that i load, manipulate and print. How can i achieve the same result if i am only given an XSD?

String xml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>" + 
                "<ns0:store_msg xmlns:ns0=\"http://data\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:schemaLocation=\"http://data sample.xsd \">" + 
                "<item>" +
                "<name>A</name>" +
                "<price>1.1</price>" +
                "</item>" +
                "<item>" +
                "<name>B</name>" +
                "<price>2.2</price>" +
                "</item>" +
                "</ns0:store_msg>";

    // load XML
    DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = builderFactory.newDocumentBuilder();
    Document doc = builder.parse(new ByteArrayInputStream(xml.getBytes()));


    // manipulate XML
    Node root = doc.getFirstChild();
    Element el = doc.createElement("item");
    Element name = doc.createElement("name");
    Element price = doc.createElement("price");
    name.setTextContent("C");
    price.setTextContent("2.2");
    el.appendChild(name);
    el.appendChild(price);
    root.appendChild(el);

    // print XML
    TransformerFactory tf = TransformerFactory.newInstance();
    Transformer transformer = tf.newTransformer();
    transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "no");
    transformer.setOutputProperty(OutputKeys.METHOD, "xml");
    transformer.setOutputProperty(OutputKeys.INDENT, "yes");
    transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
    transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");

    transformer.transform(new DOMSource(doc), 
         new StreamResult(new OutputStreamWriter(System.out, "UTF-8")));

Agreed - use JAXB. dzone.com/articles/introduction-to-jaxb-20 — Michael Peacock
– Michael Peacock, Commented Jul 12, 2017 at 16:13
Thank you for your response. I am a little confused about the use of JAXB. Pardon the novice question but would JAXB produce source code of a POJO outside of runtime and then this unmarshaled code can be compiled and used, or can JAXB actually create an object at runtime based on the gives schema and the this object could be manipulated and marshalled to raw XML in, lets say, a file ? — VilleLipponen
– VilleLipponen, Commented Jul 12, 2017 at 16:35
What you’re asking isn’t really feasible. XSDs are pretty versatile. What would a sample XML document contain for an element declared in the XSD with minOccurs="0"? What would a sample XML document contain for an element whose type is defined with <choice>? — VGR
– VGR, Commented Jul 12, 2017 at 17:28
@VGR - you are partially correct, but... it is possible by deciding what to do with such things. Actualy many tools do it, at least XMLSpy, SOAPUI - and they ask user to define what to do. — Vadim
– Vadim, Commented Jul 12, 2017 at 17:51

Vadim · Accepted Answer · 2017-07-12 18:25:00Z

A. use JAXB (preferable):

pre-step: generate JAXB Java classes out of your XSD, as example by maven-jaxb2-plugin or with other tools or manually calling XJC compiler
when you have needed classes create your root element:

StoreMsg myStoreMsgRoot = new StoreMsg(); // Class must be what JAXB generated for store_msg element

populate needed elements in it as you wish. as example:

 Item firstItem = new Item();
 firstItem.setName("A");
 firstItem.setPrice(1.1);
 myStoreMsgRoot.getItem().add(firstItem);

and so on

Then marshal your root element with JAXBContext as example to String

JAXBContext jaxbCtx = JAXBContext.newInstance(StoreMsg.class); ByteArrayOutputStream bos = new ByteArrayOutputStream(); jaxbCtx.createMarshaller().marshal(myStoreMsgRoot, bos); String generatedXml = new String(bos.toByteArray()); bos.close();

B. there is a framework to do it - jlibs.

Simple example is here: jlibs - XSInstance.wiki

Aside of that you may need to set bunch of properties to deal with cases @VCR commented about.

From first glance it works somehow.

Just latest versions need dependencies (through Maven as below or jar files in the classpath):

    <!-- https://mvnrepository.com/artifact/in.jlibs/jlibs-xsd -->
    <dependency>
        <groupId>in.jlibs</groupId>
        <artifactId>jlibs-xsd</artifactId>
        <version>2.2.1</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/in.jlibs/jlibs-xml -->
    <dependency>
        <groupId>in.jlibs</groupId>
        <artifactId>jlibs-xml</artifactId>
        <version>2.1</version>
    </dependency>

    <dependency>
        <groupId>xerces</groupId>
        <artifactId>xerces</artifactId>
        <version>2.4.0</version>
    </dependency>

    <dependency>
        <groupId>xerces</groupId>
        <artifactId>xercesImpl</artifactId>
        <version>2.11.0-22</version>
    </dependency>

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