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EclipseLink/UserGuide/MOXy/Runtime/Convert Objects to XML/Events
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Validating against an XML Schema
Consider the following object model:
package blog.jaxb.validation; import java.util.ArrayList; import java.util.List; import javax.xml.bind.annotation.XmlElement; import javax.xml.bind.annotation.XmlRootElement; @XmlRootElement public class Customer { private String name; private List<PhoneNumber> phoneNumbers = new ArrayList<PhoneNumber>(); public String getName() { return name; } public void setName(String name) { this.name = name; } @XmlElement(name="phone-number") public List<PhoneNumber> getPhoneNumbers() { return phoneNumbers; } public void setPhoneNumbers(List<PhoneNumber> phoneNumbers) { this.phoneNumbers = phoneNumbers; } } package blog.jaxb.validation; public class PhoneNumber { }
Notice that the model classes do not contain any validation specific information.
The sample code uses the following XML schema:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="customer"> <xs:complexType> <xs:sequence> <xs:element name="name" type="stringMaxSize5"/> <xs:element ref="phone-number" maxOccurs="2"/> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="phone-number"> <xs:complexType> <xs:sequence/> </xs:complexType> </xs:element> <xs:simpleType name="stringMaxSize5"> <xs:restriction base="xs:string"> <xs:maxLength value="5"/> </xs:restriction> </xs:simpleType> </xs:schema>
Notice the following constraints:
- The customer's name cannot be longer than 5 characters.
- The customer cannot have more than 2 phone numbers.
ValidationEventHandler
JAXB reports validation events through the ValidationEventHandler. The event is represented as an instance of ValidationEvent, and provides many details about the issue. The data is similar to what is available from a SAXParseException.
Returning false from the handleEvent method will cause the JAXB operation to stop.
Returning true will allow the method to continue, if possible.
package blog.jaxb.validation; import javax.xml.bind.ValidationEvent; import javax.xml.bind.ValidationEventHandler; public class MyValidationEventHandler implements ValidationEventHandler { public boolean handleEvent(ValidationEvent event) { System.out.println("\nEVENT"); System.out.println("SEVERITY: " + event.getSeverity()); System.out.println("MESSAGE: " + event.getMessage()); System.out.println("LINKED EXCEPTION: " + event.getLinkedException()); System.out.println("LOCATOR"); System.out.println(" LINE NUMBER: " + event.getLocator().getLineNumber()); System.out.println(" COLUMN NUMBER: " + event.getLocator().getColumnNumber()); System.out.println(" OFFSET: " + event.getLocator().getOffset()); System.out.println(" OBJECT: " + event.getLocator().getObject()); System.out.println(" NODE: " + event.getLocator().getNode()); System.out.println(" URL: " + event.getLocator().getURL()); return true; } }
Marshalling
To enable validation, an instance of Schema must be set on the Marshaller. To handle the events an implementation of ValidationEventHandler must also be set.
package blog.jaxb.validation; import java.io.File; import javax.xml.XMLConstants; import javax.xml.bind.JAXBContext; import javax.xml.bind.Marshaller; import javax.xml.validation.Schema; import javax.xml.validation.SchemaFactory; public class MarshalDemo { public static void main(String[] args) throws Exception { Customer customer = new Customer(); customer.setName("Jane Doe"); customer.getPhoneNumbers().add(new PhoneNumber()); customer.getPhoneNumbers().add(new PhoneNumber()); customer.getPhoneNumbers().add(new PhoneNumber()); SchemaFactory sf = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI); Schema schema = sf.newSchema(new File("customer.xsd")); JAXBContext jc = JAXBContext.newInstance(Customer.class); Marshaller marshaller = jc.createMarshaller(); marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); marshaller.setSchema(schema); marshaller.setEventHandler(new MyValidationEventHandler()); marshaller.marshal(customer, System.out); } }
Output
The validation performed during the marshal raised 3 events. The first 2 events are related to the text value of the "name" element being too long. The 3rd event is related to the extra "phone-number" element.
EVENT SEVERITY: 1 MESSAGE: cvc-maxLength-valid: Value 'Jane Doe' with length = '8' is not facet-valid with respect to maxLength '5' for type 'stringWithMaxSize5'. LINKED EXCEPTION: org.eclipse.persistence.oxm.record.ValidatingMarshalRecord$MarshalSAXParseException: cvc-maxLength-valid: Value 'Jane Doe' with length = '8' is not facet-valid with respect to maxLength '5' for type 'stringWithMaxSize5'. LOCATOR LINE NUMBER: -1 COLUMN NUMBER: -1 OFFSET: -1 OBJECT: blog.jaxb.validation.Customer@10045eb NODE: null URL: null EVENT SEVERITY: 1 MESSAGE: cvc-type.3.1.3: The value 'Jane Doe' of element 'name' is not valid. LINKED EXCEPTION: org.eclipse.persistence.oxm.record.ValidatingMarshalRecord$MarshalSAXParseException: cvc-type.3.1.3: The value 'Jane Doe' of element 'name' is not valid. LOCATOR LINE NUMBER: -1 COLUMN NUMBER: -1 OFFSET: -1 OBJECT: blog.jaxb.validation.Customer@10045eb NODE: null URL: null EVENT SEVERITY: 1 MESSAGE: cvc-complex-type.2.4.d: Invalid content was found starting with element 'customer'. No child element '{phone-number}' is expected at this point. LINKED EXCEPTION: org.eclipse.persistence.oxm.record.ValidatingMarshalRecord$MarshalSAXParseException: cvc-complex-type.2.4.d: Invalid content was found starting with element 'customer'. No child element '{phone-number}' is expected at this point. LOCATOR LINE NUMBER: -1 COLUMN NUMBER: -1 OFFSET: -1 OBJECT: blog.jaxb.validation.Customer@10045eb NODE: null URL: null
<customer> <name>Jane Doe</name> <phone-number/> <phone-number/> <phone-number/> </customer> </xml>