As of JAXB 2.0, this class is deprecated and optional.
The Validator class is responsible for controlling the validation
of content trees during runtime.
Three Forms of Validation
- Unmarshal-Time Validation
- This form of validation enables a client application to receive
information about validation errors and warnings detected while
unmarshalling XML data into a Java content tree and is completely
orthogonal to the other types of validation. To enable or disable
it, see the javadoc for
Unmarshaller.setValidating
.
All JAXB 1.0 Providers are required to support this operation.
- On-Demand Validation
- This form of validation enables a client application to receive
information about validation errors and warnings detected in the
Java content tree. At any point, client applications can call
the
Validator.validate
method
on the Java content tree (or any sub-tree of it). All JAXB 1.0
Providers are required to support this operation.
- Fail-Fast Validation
- This form of validation enables a client application to receive
immediate feedback about modifications to the Java content tree
that violate type constraints on Java Properties as defined in
the specification. JAXB Providers are not required support
this type of validation. Of the JAXB Providers that do support
this type of validation, some may require you to decide at schema
compile time whether or not a client application will be allowed
to request fail-fast validation at runtime.
The Validator class is responsible for managing On-Demand Validation.
The Unmarshaller class is responsible for managing Unmarshal-Time
Validation during the unmarshal operations. Although there is no formal
method of enabling validation during the marshal operations, the
Marshaller may detect errors, which will be reported to the
ValidationEventHandler registered on it.
Using the Default EventHandler
If the client application does not set an event handler on their
Validator, Unmarshaller, or Marshaller prior to
calling the validate, unmarshal, or marshal methods, then a default event
handler will receive notification of any errors or warnings encountered.
The default event handler will cause the current operation to halt after
encountering the first error or fatal error (but will attempt to continue
after receiving warnings).
Handling Validation Events
There are three ways to handle events encountered during the unmarshal,
validate, and marshal operations:
- Use the default event handler
- The default event handler will be used if you do not specify one
via the setEventHandler API's on Validator,
Unmarshaller, or Marshaller.
- Implement and register a custom event handler
- Client applications that require sophisticated event processing
can implement the ValidationEventHandler interface and
register it with the Unmarshaller and/or
Validator.
- Use the
ValidationEventCollector
utility
- For convenience, a specialized event handler is provided that
simply collects any ValidationEvent objects created
during the unmarshal, validate, and marshal operations and
returns them to the client application as a
java.util.Collection.
Validation and Well-Formedness
Validation events are handled differently depending on how the client
application is configured to process them as described in the previous
section. However, there are certain cases where a JAXB Provider indicates
that it is no longer able to reliably detect and report errors. In these
cases, the JAXB Provider will set the severity of the ValidationEvent to
FATAL_ERROR to indicate that the unmarshal, validate, or marshal operations
should be terminated. The default event handler and
ValidationEventCollector utility class must terminate processing
after being notified of a fatal error. Client applications that supply their
own ValidationEventHandler should also terminate processing after
being notified of a fatal error. If not, unexpected behaviour may occur.
Supported Properties
There currently are not any properties required to be supported by all
JAXB Providers on Validator. However, some providers may support
their own set of provider specific properties.