Java - Generating XML data dynamically via Input records - java

I have to generate the following format of XML using java:
<document>
<creditDetails>
<accountNo>123456</accountNo>
</creditDetails>
<creditDetails>
<accountNo>123123</accountNo>
</creditDetails>
.
.
.
...
</document>
Now, I have created the above provided XML using the Document.appendChild and relevant XML code.
When I have to create a new block of Credit Details, I have to create a new XML component which is a very bad practice.
I have lets say 15 records and I have iterated those records one by one to create a single xml format for all of them as provided in my question.
Can someone guide me? How I can achieve this?

The correct way would be to use JAXB (Java Architecture for XML Binding).
Then you should have the following data classes:
#XmlRootElement(name = "document")
public class Document {
private List<CreditDetail> creditDetails = new ArrayList<>();
public List<CreditDetail> getCreditDetails() {
return creditDetails;
}
}
public class CreditDetail {
private int accountNo;
public int getAccountNo() {
return accountNo;
}
public void setAccountNo(int accountNo) {
this.accountNo = accountNo;
}
}
Now you can just create your account data in Java and the Marshaller will do the work for you:
Document doc = new Document();
CreditDetail creditDetail1 = new CreditDetail();
creditDetail1.setAccountNo(123456);
doc.getCreditDetails().add(creditDetail1);
CreditDetail creditDetail2 = new CreditDetail();
creditDetail2.setAccountNo(123123);
doc.getCreditDetails().add(creditDetail2);
// could make your classes a bit more pretty, e.g. Factory methods or constructor
JAXBContext context = JAXBContext.newInstance(Document.class);
Marshaller marshaller = context.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
StringWriter writer = new StringWriter();
marshaller.marhaller(document, writer);
writer.toString() // gives your XML
Unfortunately JAXB is not included in the JDK since Java 11 so you have to add it in your dependency management.

Related

convert xml to objects java

I would appreciate your help, how can I match such xmls data in java with different tags, for example can come: <t: UserAttrs>, <ns3: UserAttrs>, <ns37: UserAttrs>
values can be different between "<" and "UserAttrs>"
I need to extract everything that is in the tag
<Rtp xmlns="http://schemas.tranzaxis.com/tran.xsd">
<Tran>
<t:Request InitiatorRid="ECACS2oob" Kind="TProcessA" LifePhase="Single" NetworkRid="V"
OrigTime="2022-07-06T08:04:00" ProcessorRid="Name" ProcessorInstId="1" OriginatorInterfaceId="1308"
xmlns=""
xmlns:ct=""
xmlns:t=""
xmlns:tc="">
<t:Parties>
<t:Term AcquirerRid="4005"><t:Caps Interactive="true"/><t:Owner Country="0" Rid="test" Title="test" Url="https://xxx" Mcc="3000"/>
</t:Term>
</t:Parties>
<t:UserAttrs>
<ct:ParamValue Rid="Reason"> <ct:Val>Authe</ct:Val>
</ct:ParamValue>
<ct:ParamValue Rid="EndTime"> <ct:Val>2022-07-06T15:04:00.462</ct:Val>
</ct:ParamValue>
</t:UserAttrs>
</t:Request>
</Tran>
You can use javax.xml.bind to unmarshall it and ignore tag namespace. Assume UserAttrs is your object class:
class UserAttrs {
#XmlElement(name = "ParamValue")
private List<ParamValue> paramValue;
}
class ParamValue {
#XmlAttribute(name = "Rid")
private String rId;
}
...
Use unmashaller:
var ctxUserAttrs = JAXBContext.newInstance(UserAttrs.class);
var inputFactory = XMLInputFactory.newInstance();
var reader = inputFactory.createXMLStreamReader(
new ByteArrayInputStream(yourXml.getBytes(StandardCharsets.UTF_8)));
// use reader.hasNext(), reader.next(), reader.nextTag() to navigate to your UserAttrs tag
var unmarshaller = ctxUserAttrs.createUnmarshaller();
var userAttrs = unmarshaller.unmarshal(reader, UserAttrs.class).getValue();
Code is untested, edit to fit your situation. I'm using akarta.xml.bind-api 2.3.3.

Should I always create an EntityResolver when parsing a xml file while validating it against a dtd?

I have a xml file and I want to convert it into a java object using JAXB. I am getting an exception related to validation. It seems JAXB is validating it against the DTD which is declared in the xml file. Unfortunately the DTD is not at the location which is mentioned in the xml file. So I kept a local copy and used an EntityResolver to make JAXB use the local DTD. And the code worked like a charm.
Below is the code
JAXBContext context = JAXBContext.newInstance(Student.class);
Unmarshaller unmarshaller = context.createUnmarshaller();
final SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
final XMLReader reader = saxParserFactory.newSAXParser().getXMLReader();
reader.setEntityResolver(new EntityResolver() {
#Override
public InputSource resolveEntity(final String publicId, final String systemId) throws SAXException, IOException {
return new InputSource(getClass().getResourceAsStream("/student.dtd"));
}
});
final SAXSource saxSource = new SAXSource(reader, new InputSource(inputStream));
student = (Student) unmarshaller.unmarshal(saxSource);
This code is inside my method parse(xmlFilePath). Every time I call parse method a new EntityResolver is created. Is this not redundant? Can I create one EntityResolver in the class's constructor and pass it to the setEntityResolver method?
public StudentParser() {
this.entityResolver = new EntityResolver() {
#Override
public InputSource resolveEntity(final String publicId, final String systemId) throws SAXException, IOException {
return new InputSource(getClass().getResourceAsStream("/student.dtd"));
}
}
}
Inside parse method
public Student parse(filePath) {
...
...
reader.setEntityResolver(this.entityResolver);
...
}
First of all, check these answers:
How to disable DTD fetching using JAXB2.0
Make DocumentBuilder.parse ignore DTD references
How to read well formed XML in Java, but skip the schema?
How do I turn off validation when parsing well-formed XML using DocumentBuilder.parse?
How to ignore inline DTD when parsing XML file in Java
In short, you can disable the DTD processing completely.
Next, as long as your entity resolver is thread-safe and reusable you definitely don't need to create new instances every time.

How to generate multiple, slightly different XSD schemas from one Java model with JAXB?

I have a set of related Java classes, which are able to hold data I need. Below is a simplified class diagram of what I have:
Now I need to import data from XML and for that I want to generate XSD schema. The problem is that I want several XSD schemas like this:
One that allows the whole data graph to be imported.
One that allows only RootNote.fieldA and ChildNodeA.
One that allows only RootNote.fieldB and ChildNodeB.
I can easily generate XSD that meets the requirements of nr.1 using JAXB (programmatically). But is there a way to do that for cases nr.2 and nr.3 for the same classes? In other words, it seems I need something like "profiles" in JAXB.
Update:
Here is how I generate XSD schema:
JAXBContext jc = JAXBContext.newInstance(RootNode.class);
final File baseDir = new File(".");
class MySchemaOutputResolver extends SchemaOutputResolver {
public Result createOutput( String namespaceUri, String suggestedFileName ) throws IOException {
return new StreamResult(new File(baseDir,suggestedFileName));
}
}
jc.generateSchema(new MySchemaOutputResolver());
This is not a full answer, just an idea.
You probably use the javax.xml.bind.JAXBContext.generateSchema(SchemaOutputResolver) method to generate your schema, so you basically use a specific JAXBContext instance. This instance is built based on the annotations in classes. When building the context, these annotations are read an organized into a model which is then used for all the operations.
So to generate different schemas you probably need to create different contexts. You can't change the annotations per case, but you can read annotations in different ways.
Take a look at the AnnotationReader. This is what JAXB RI uses behind the scenes to load annotations from Java classes. You can create your own implementation and use it when creating the JAXBContext. Here's an example of something similar:
final AnnotationReader<Type, Class, Field, Method> annotationReader = new AnnoxAnnotationReader();
final Map<String, Object> properties = new HashMap<String, Object>();
properties.put(JAXBRIContext.ANNOTATION_READER, annotationReader);
final JAXBContext context = JAXBContext.newInstance(
"org.jvnet.annox.samples.po",
Thread.currentThread().getContextClassLoader(),
properties);
So how about writing your own annotation reader, which would consider what you call "profiles"? You can invent your own annotation #XmlSchemaProfile(name="foo"). Your annotation reader would then check if this annotation is present with the desired value and then either return it or ignore it. You'll be able to build different contexts from the same Java model - and consequently produce different schemas according to profiles defined by your #XmlSchemaProfile annotations.
I found a solution that suited me. The idea is to output the result of XSD generation into an XML Document (in-memory DOM). JAXB allows that. After this, you can manipulate the document any way you wish, adding or removing parts.
I wrote some filters that whitelist or blacklist fields (in XSD they are elements) and classes (in XSD they are complex types). While I see a lot of potential problems with this approach, it did the job in my case. Below is the code for case 2 schema:
// This SchemaOutputResolver implementation saves XSD into DOM
static class DOMResultSchemaOutputResolver extends SchemaOutputResolver {
private List<DOMResult> results = new LinkedList<DOMResult>();
#Override
public Result createOutput(String ns, String file) throws IOException {
DOMResult result = new DOMResult();
result.setSystemId(file);
results.add(result);
return result;
}
public Document getDocument() {
return (Document)results.get(0).getNode();
}
public String getFilename() {
return results.get(0).getSystemId();
}
}
// This method serializes the DOM into file
protected void serializeXsdToFile(Document xsdDocument, String filename) throws IOException {
OutputFormat format = new OutputFormat(xsdDocument);
format.setIndenting(true);
FileOutputStream os = new FileOutputStream(filename);
XMLSerializer serializer = new XMLSerializer(os, format);
serializer.serialize(xsdDocument);
}
#Test
public void generateSchema2() throws JAXBException, IOException, XPathExpressionException {
JAXBContext context = JAXBContext.newInstance(RootNode.class);
DOMResultSchemaOutputResolver schemaOutputResolver = new DOMResultSchemaOutputResolver();
context.generateSchema(schemaOutputResolver);
// Do your manipulations here as you want. Below is just an example!
filterXsdDocumentComplexTypes(schemaOutputResolver.getDocument(), asList("childNodeA"), true);
filterXsdDocumentElements(schemaOutputResolver.getDocument(), asList("fieldB"));
serializeXsdToFile(schemaOutputResolver.getDocument(), "xf.xsd");
}
private boolean shouldComplexTypeBeDeleted(String complexTypeName, List<String> complexTypes, boolean whitelist) {
return (whitelist && !complexTypes.contains(complexTypeName)) || (!whitelist && complexTypes.contains(complexTypeName));
}
protected void filterXsdDocumentComplexTypes(Document xsdDocument, List<String> complexTypes, boolean whitelist) throws XPathExpressionException {
XPath xPath = XPathFactory.newInstance().newXPath();
NodeList complexTypeNodes = (NodeList)xPath.evaluate("//*[local-name() = 'complexType']", xsdDocument, XPathConstants.NODESET);
for (int i = 0; i < complexTypeNodes.getLength(); i++) {
Node node = complexTypeNodes.item(i);
Node complexTypeNameNode = node.getAttributes().getNamedItem("name");
if (complexTypeNameNode != null) {
if (shouldComplexTypeBeDeleted(complexTypeNameNode.getNodeValue(), complexTypes, whitelist)) {
node.getParentNode().removeChild(node);
}
}
}
NodeList elements = (NodeList)xPath.evaluate("//*[local-name() = 'element']", xsdDocument, XPathConstants.NODESET);
for (int i = 0; i < elements.getLength(); i++) {
Node node = elements.item(i);
Node typeNameNode = node.getAttributes().getNamedItem("type");
if (typeNameNode != null) {
if (shouldComplexTypeBeDeleted(typeNameNode.getNodeValue(), complexTypes, whitelist) && !typeNameNode.getNodeValue().startsWith("xs")) {
node.getParentNode().removeChild(node);
}
}
}
}
protected void filterXsdDocumentElements(Document xsdDocument, List<String> blacklistedElements) throws XPathExpressionException {
XPath xPath = XPathFactory.newInstance().newXPath();
NodeList elements = (NodeList)xPath.evaluate("//*[local-name() = 'element']", xsdDocument, XPathConstants.NODESET);
for (int i = 0; i < elements.getLength(); i++) {
Node node = elements.item(i);
if (blacklistedElements.contains(node.getAttributes().getNamedItem("name").getNodeValue())) {
node.getParentNode().removeChild(node);
}
}
}

Suitable XML schema for Marshaller setSchema

I'm having a hard time figuring out the correct schema (to validate the structure and data types) of simple classes. For example, I could get answer for Employee class with schemagen (supplied with JDK), but still could not get it to work for HumanResources.
I'm trying to serialize collection of Employee class instances to XML. For that, I have created class HumanResources, that contains a list of Employee class elements. Example:
ArrayList<Employee> ems = getTestData();
HumanResources hm = new HumanResources(ems);
SchemaFactory sf = SchemaFactory.newInstance(javax.xml.XMLConstants.W3C_XML_SCHEMA_NS_URI);
JAXBContext jaxbContext = JAXBContext.newInstance(HumanResources.class);
Marshaller marshaller = jaxbContext.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.setSchema(sf.newSchema(new File("src\\server\\HumanResources.xsd")));
marshaller.marshal( new JAXBElement<HumanResources>(
new QName(null, "HumanResources"), HumanResources.class, hm), os);
Below is an example of how to create an XML schema using the JAXBContext:
First you must create a class that extends javax.xml.bind.SchemaOutputResolver.
public class MySchemaOutputResolver extends SchemaOutputResolver {
public Result createOutput(String namespaceURI, String suggestedFileName) throws IOException {
File file = new File(suggestedFileName);
StreamResult result = new StreamResult(file);
result.setSystemId(file.toURI().toURL().toString());
return result;
}
}
Then use an instance of this class with JAXBContext to capture the generated XML Schema.
Class[] classes = new Class[4];
classes[0] = org.example.customer_example.AddressType.class;
classes[1] = org.example.customer_example.ContactInfo.class;
classes[2] = org.example.customer_example.CustomerType.class;
classes[3] = org.example.customer_example.PhoneNumber.class;
JAXBContext jaxbContext = JAXBContext.newInstance(classes);
SchemaOutputResolver sor = new MySchemaOutputResolver();
jaxbContext.generateSchema(sor);
For more information see:
http://wiki.eclipse.org/EclipseLink/Examples/MOXy/JAXB/GenerateSchema

How to validate an XML file against an XSD file?

I'm generating some xml files that needs to conform to an xsd file that was given to me. How should I verify they conform?
The Java runtime library supports validation. Last time I checked this was the Apache Xerces parser under the covers. You should probably use a javax.xml.validation.Validator.
import javax.xml.XMLConstants;
import javax.xml.transform.Source;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.*;
import java.net.URL;
import org.xml.sax.SAXException;
//import java.io.File; // if you use File
import java.io.IOException;
...
URL schemaFile = new URL("http://host:port/filename.xsd");
// webapp example xsd:
// URL schemaFile = new URL("http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd");
// local file example:
// File schemaFile = new File("/location/to/localfile.xsd"); // etc.
Source xmlFile = new StreamSource(new File("web.xml"));
SchemaFactory schemaFactory = SchemaFactory
.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
try {
Schema schema = schemaFactory.newSchema(schemaFile);
Validator validator = schema.newValidator();
validator.validate(xmlFile);
System.out.println(xmlFile.getSystemId() + " is valid");
} catch (SAXException e) {
System.out.println(xmlFile.getSystemId() + " is NOT valid reason:" + e);
} catch (IOException e) {}
The schema factory constant is the string http://www.w3.org/2001/XMLSchema which defines XSDs. The above code validates a WAR deployment descriptor against the URL http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd but you could just as easily validate against a local file.
You should not use the DOMParser to validate a document (unless your goal is to create a document object model anyway). This will start creating DOM objects as it parses the document - wasteful if you aren't going to use them.
Here's how to do it using Xerces2. A tutorial for this, here (req. signup).
Original attribution: blatantly copied from here:
import org.apache.xerces.parsers.DOMParser;
import java.io.File;
import org.w3c.dom.Document;
public class SchemaTest {
public static void main (String args[]) {
File docFile = new File("memory.xml");
try {
DOMParser parser = new DOMParser();
parser.setFeature("http://xml.org/sax/features/validation", true);
parser.setProperty(
"http://apache.org/xml/properties/schema/external-noNamespaceSchemaLocation",
"memory.xsd");
ErrorChecker errors = new ErrorChecker();
parser.setErrorHandler(errors);
parser.parse("memory.xml");
} catch (Exception e) {
System.out.print("Problem parsing the file.");
}
}
}
We build our project using ant, so we can use the schemavalidate task to check our config files:
<schemavalidate>
<fileset dir="${configdir}" includes="**/*.xml" />
</schemavalidate>
Now naughty config files will fail our build!
http://ant.apache.org/manual/Tasks/schemavalidate.html
Since this is a popular question, I will point out that java can also validate against "referred to" xsd's, for instance if the .xml file itself specifies XSD's in the header, using xsi:schemaLocation or xsi:noNamespaceSchemaLocation (or xsi for particular namespaces) ex:
<document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="http://www.example.com/document.xsd">
...
or schemaLocation (always a list of namespace to xsd mappings)
<document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.example.com/my_namespace http://www.example.com/document.xsd">
...
The other answers work here as well, because the .xsd files "map" to the namespaces declared in the .xml file, because they declare a namespace, and if matches up with the namespace in the .xml file, you're good. But sometimes it's convenient to be able to have a custom resolver...
From the javadocs: "If you create a schema without specifying a URL, file, or source, then the Java language creates one that looks in the document being validated to find the schema it should use. For example:"
SchemaFactory factory = SchemaFactory.newInstance("http://www.w3.org/2001/XMLSchema");
Schema schema = factory.newSchema();
and this works for multiple namespaces, etc.
The problem with this approach is that the xmlsns:xsi is probably a network location, so it'll by default go out and hit the network with each and every validation, not always optimal.
Here's an example that validates an XML file against any XSD's it references (even if it has to pull them from the network):
public static void verifyValidatesInternalXsd(String filename) throws Exception {
InputStream xmlStream = new new FileInputStream(filename);
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setValidating(true);
factory.setNamespaceAware(true);
factory.setAttribute("http://java.sun.com/xml/jaxp/properties/schemaLanguage",
"http://www.w3.org/2001/XMLSchema");
DocumentBuilder builder = factory.newDocumentBuilder();
builder.setErrorHandler(new RaiseOnErrorHandler());
builder.parse(new InputSource(xmlStream));
xmlStream.close();
}
public static class RaiseOnErrorHandler implements ErrorHandler {
public void warning(SAXParseException e) throws SAXException {
throw new RuntimeException(e);
}
public void error(SAXParseException e) throws SAXException {
throw new RuntimeException(e);
}
public void fatalError(SAXParseException e) throws SAXException {
throw new RuntimeException(e);
}
}
You can avoid pulling referenced XSD's from the network, even though the xml files reference url's, by specifying the xsd manually (see some other answers here) or by using an "XML catalog" style resolver. Spring apparently also can intercept the URL requests to serve local files for validations. Or you can set your own via setResourceResolver, ex:
Source xmlFile = new StreamSource(xmlFileLocation);
SchemaFactory schemaFactory = SchemaFactory
.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
Schema schema = schemaFactory.newSchema();
Validator validator = schema.newValidator();
validator.setResourceResolver(new LSResourceResolver() {
#Override
public LSInput resolveResource(String type, String namespaceURI,
String publicId, String systemId, String baseURI) {
InputSource is = new InputSource(
getClass().getResourceAsStream(
"some_local_file_in_the_jar.xsd"));
// or lookup by URI, etc...
return new Input(is); // for class Input see
// https://stackoverflow.com/a/2342859/32453
}
});
validator.validate(xmlFile);
See also here for another tutorial.
I believe the default is to use DOM parsing, you can do something similar with SAX parser that is validating as well saxReader.setEntityResolver(your_resolver_here);
Using Java 7 you can follow the documentation provided in package description.
// create a SchemaFactory capable of understanding WXS schemas
SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
// load a WXS schema, represented by a Schema instance
Source schemaFile = new StreamSource(new File("mySchema.xsd"));
Schema schema = factory.newSchema(schemaFile);
// create a Validator instance, which can be used to validate an instance document
Validator validator = schema.newValidator();
// validate the DOM tree
try {
validator.validate(new StreamSource(new File("instance.xml"));
} catch (SAXException e) {
// instance document is invalid!
}
If you have a Linux-Machine you could use the free command-line tool SAXCount. I found this very usefull.
SAXCount -f -s -n my.xml
It validates against dtd and xsd.
5s for a 50MB file.
In debian squeeze it is located in the package "libxerces-c-samples".
The definition of the dtd and xsd has to be in the xml! You can't config them separately.
With JAXB, you could use the code below:
#Test
public void testCheckXmlIsValidAgainstSchema() {
logger.info("Validating an XML file against the latest schema...");
MyValidationEventCollector vec = new MyValidationEventCollector();
validateXmlAgainstSchema(vec, inputXmlFileName, inputXmlSchemaName, inputXmlRootClass);
assertThat(vec.getValidationErrors().isEmpty(), is(expectedValidationResult));
}
private void validateXmlAgainstSchema(final MyValidationEventCollector vec, final String xmlFileName, final String xsdSchemaName, final Class<?> rootClass) {
try (InputStream xmlFileIs = Thread.currentThread().getContextClassLoader().getResourceAsStream(xmlFileName);) {
final JAXBContext jContext = JAXBContext.newInstance(rootClass);
// Unmarshal the data from InputStream
final Unmarshaller unmarshaller = jContext.createUnmarshaller();
final SchemaFactory sf = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
final InputStream schemaAsStream = Thread.currentThread().getContextClassLoader().getResourceAsStream(xsdSchemaName);
unmarshaller.setSchema(sf.newSchema(new StreamSource(schemaAsStream)));
unmarshaller.setEventHandler(vec);
unmarshaller.unmarshal(new StreamSource(xmlFileIs), rootClass).getValue(); // The Document class is the root object in the XML file you want to validate
for (String validationError : vec.getValidationErrors()) {
logger.trace(validationError);
}
} catch (final Exception e) {
logger.error("The validation of the XML file " + xmlFileName + " failed: ", e);
}
}
class MyValidationEventCollector implements ValidationEventHandler {
private final List<String> validationErrors;
public MyValidationEventCollector() {
validationErrors = new ArrayList<>();
}
public List<String> getValidationErrors() {
return Collections.unmodifiableList(validationErrors);
}
#Override
public boolean handleEvent(final ValidationEvent event) {
String pattern = "line {0}, column {1}, error message {2}";
String errorMessage = MessageFormat.format(pattern, event.getLocator().getLineNumber(), event.getLocator().getColumnNumber(),
event.getMessage());
if (event.getSeverity() == ValidationEvent.FATAL_ERROR) {
validationErrors.add(errorMessage);
}
return true; // you collect the validation errors in a List and handle them later
}
}
One more answer: since you said you need to validate files you are generating (writing), you might want to validate content while you are writing, instead of first writing, then reading back for validation. You can probably do that with JDK API for Xml validation, if you use SAX-based writer: if so, just link in validator by calling 'Validator.validate(source, result)', where source comes from your writer, and result is where output needs to go.
Alternatively if you use Stax for writing content (or a library that uses or can use stax), Woodstox can also directly support validation when using XMLStreamWriter. Here's a blog entry showing how that is done:
If you are generating XML files programatically, you may want to look at the XMLBeans library. Using a command line tool, XMLBeans will automatically generate and package up a set of Java objects based on an XSD. You can then use these objects to build an XML document based on this schema.
It has built-in support for schema validation, and can convert Java objects to an XML document and vice-versa.
Castor and JAXB are other Java libraries that serve a similar purpose to XMLBeans.
Using Woodstox, configure the StAX parser to validate against your schema and parse the XML.
If exceptions are caught the XML is not valid, otherwise it is valid:
// create the XSD schema from your schema file
XMLValidationSchemaFactory schemaFactory = XMLValidationSchemaFactory.newInstance(XMLValidationSchema.SCHEMA_ID_W3C_SCHEMA);
XMLValidationSchema validationSchema = schemaFactory.createSchema(schemaInputStream);
// create the XML reader for your XML file
WstxInputFactory inputFactory = new WstxInputFactory();
XMLStreamReader2 xmlReader = (XMLStreamReader2) inputFactory.createXMLStreamReader(xmlInputStream);
try {
// configure the reader to validate against the schema
xmlReader.validateAgainst(validationSchema);
// parse the XML
while (xmlReader.hasNext()) {
xmlReader.next();
}
// no exceptions, the XML is valid
} catch (XMLStreamException e) {
// exceptions, the XML is not valid
} finally {
xmlReader.close();
}
Note: If you need to validate multiple files, you should try to reuse your XMLInputFactory and XMLValidationSchema in order to maximize the performance.
Are you looking for a tool or a library?
As far as libraries goes, pretty much the de-facto standard is Xerces2 which has both C++ and Java versions.
Be fore warned though, it is a heavy weight solution. But then again, validating XML against XSD files is a rather heavy weight problem.
As for a tool to do this for you, XMLFox seems to be a decent freeware solution, but not having used it personally I can't say for sure.
Validate against online schemas
Source xmlFile = new StreamSource(Thread.currentThread().getContextClassLoader().getResourceAsStream("your.xml"));
SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
Schema schema = factory.newSchema(Thread.currentThread().getContextClassLoader().getResource("your.xsd"));
Validator validator = schema.newValidator();
validator.validate(xmlFile);
Validate against local schemas
Offline XML Validation with Java
I had to validate an XML against XSD just one time, so I tried XMLFox. I found it to be very confusing and weird. The help instructions didn't seem to match the interface.
I ended up using LiquidXML Studio 2008 (v6) which was much easier to use and more immediately familiar (the UI is very similar to Visual Basic 2008 Express, which I use frequently). The drawback: the validation capability is not in the free version, so I had to use the 30 day trial.

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