SchemaFactory is a schema compiler. It reads external representations of schemas and prepares them for validation.
The SchemaFactory class is not thread-safe. In other words, it is the application's responsibility to ensure that at most one thread is using a SchemaFactory object at any given moment. Implementations are encouraged to mark methods as synchronized to protect themselves from broken clients.
SchemaFactory
is not re-entrant. While one of the
newSchema
methods is being invoked, applications
may not attempt to recursively invoke the newSchema
method,
even from the same thread.
This spec uses a namespace URI to designate a schema language. The following table shows the values defined by this specification.
To be compliant with the spec, the implementation is only required to support W3C XML Schema 1.0. However, if it chooses to support other schema languages listed here, it must conform to the relevant behaviors described in this spec.
Schema languages not listed here are expected to introduce their own URIs to represent themselves. The SchemaFactory class is capable of locating other implementations for other schema languages at run-time.
Note that because the XML DTD is strongly tied to the parsing process and has a significant effect on the parsing process, it is impossible to define the DTD validation as a process independent from parsing. For this reason, this specification does not define the semantics for the XML DTD. This doesn't prohibit implentors from implementing it in a way they see fit, but users are warned that any DTD validation implemented on this interface necessarily deviate from the XML DTD semantics as defined in the XML 1.0.
value | language |
---|---|
javax.xml.XMLConstants#W3C_XML_SCHEMA_NS_URI
("http://www.w3.org/2001/XMLSchema ") |
W3C XML Schema 1.0 |
javax.xml.XMLConstants#RELAXNG_NS_URI
("http://relaxng.org/ns/structure/1.0 ") |
RELAX NG 1.0 |
The equals
method implements an equivalence relation
on non-null object references:
x
, x.equals(x)
should return
true
.
x
and y
, x.equals(y)
should return true
if and only if
y.equals(x)
returns true
.
x
, y
, and z
, if
x.equals(y)
returns true
and
y.equals(z)
returns true
, then
x.equals(z)
should return true
.
x
and y
, multiple invocations of
x.equals(y) consistently return true
or consistently return false
, provided no
information used in equals
comparisons on the
objects is modified.
x
,
x.equals(null)
should return false
.
The equals method for class Object
implements
the most discriminating possible equivalence relation on objects;
that is, for any non-null reference values x
and
y
, this method returns true
if and only
if x
and y
refer to the same object
(x == y
has the value true
).
Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.
The feature name is any fully-qualified URI. It is possible for a SchemaFactory to recognize a feature name but temporarily be unable to return its value.
Implementors are free (and encouraged) to invent their own features, using names built on their own URIs.
The property name is any fully-qualified URI. It is possible for a SchemaFactory to recognize a property name but temporarily be unable to return its value.
SchemaFactory s are not required to recognize any specific property names.
Implementors are free (and encouraged) to invent their own properties, using names built on their own URIs.
java.util.Hashtable
.
The general contract of hashCode
is:
hashCode
method on each of
the two objects must produce the same integer result.
As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)
Is specified schema supported by this SchemaFactory
?
Lookup an implementation of the SchemaFactory
that supports the specified
schema language and return it.
To find a SchemaFactory
object for a given schema language,
this method looks the following places in the following order
where "the class loader" refers to the context class loader:
"javax.xml.validation.SchemaFactory:schemaLanguage"
is present (where schemaLanguage is the parameter
to this method), then its value is read
as a class name. The method will try to
create a new instance of this class by using the class loader,
and returns it if it is successfully created.
$java.home/lib/jaxp.properties
is read and
the value associated with the key being the system property above
is looked for. If present, the value is processed just like above.
The class loader is asked for service provider provider-configuration files matching
javax.xml.validation.SchemaFactory
in the resource directory META-INF/services.
See the JAR File Specification for file format and parsing rules.
Each potential service provider is required to implement the method:
The first service provider found in class loader order that supports the specified schema language is returned.
SchemaFactory
is located
in a implementation specific way. There must be a platform default
SchemaFactory
for W3C XML Schema.
If everything fails, IllegalArgumentException will be thrown.
Tip for Trouble-shooting:
See for exactly how a property file is parsed. In particular, colons ':' need to be escaped in a property file, so make sure schema language URIs are properly escaped in it. For example:
http\://www.w3.org/2001/XMLSchema=org.acme.foo.XSSchemaFactory
The exact semantics of the returned Schema object depends on the schema language that this SchemaFactory is created for.
Also, implementations are allowed to use implementation-specific property/feature to alter the semantics of this method.
For XML Schema, this method creates a Schema object that performs validation by using location hints specified in documents.
The returned Schema object assumes that if documents refer to the same URL in the schema location hints, they will always resolve to the same schema document. This asusmption allows implementations to reuse parsed results of schema documents so that multiple validations against the same schema will run faster.
Note that the use of schema location hints introduces a vulnerability to denial-of-service attacks.
RELAX NG does not support this operation.
The callee will read all the Source s and combine them into a single schema. The exact semantics of the combination depends on the schema language that this SchemaFactory object is created for.
When an ErrorHandler is set, the callee will report all the errors found in sources to the handler. If the handler throws an exception, it will abort the schema compilation and the same exception will be thrown from this method. Also, after an error is reported to a handler, the callee is allowed to abort the further processing by throwing it. If an error handler is not set, the callee will throw the first error it finds in the sources.
The resulting schema contains components from the specified sources. The same result would be achieved if all these sources were imported, using appropriate values for schemaLocation and namespace, into a single schema document with a different targetNamespace and no components of its own, if the import elements were given in the same order as the sources. Section 4.2.3 of the XML Schema recommendation describes the options processors have in this regard. While a processor should be consistent in its treatment of JAXP schema sources and XML Schema imports, the behaviour between JAXP-compliant parsers may vary; in particular, parsers may choose to ignore all but the first <import> for a given namespace, regardless of information provided in schemaLocation.
If the parsed set of schemas includes error(s) as specified in the section 5.1 of the XML Schema spec, then the error must be reported to the ErrorHandler .
For RELAX NG, this method must throw UnsupportedOperationException if schemas.length!=1.
wait
methods.
The awakened thread will not be able to proceed until the current thread relinquishes the lock on this object. The awakened thread will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened thread enjoys no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner of this object's monitor. A thread becomes the owner of the object's monitor in one of three ways:
synchronized
statement
that synchronizes on the object.
Class,
by executing a
synchronized static method of that class.
Only one thread at a time can own an object's monitor.
wait
methods.
The awakened threads will not be able to proceed until the current thread relinquishes the lock on this object. The awakened threads will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened threads enjoy no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify
method for a
description of the ways in which a thread can become the owner of
a monitor.
newSchema
method invocation.
Error handler can be used to customize the error handling process during schema parsing. When an ErrorHandler is set, errors found during the parsing of schemas will be first sent to the ErrorHandler .
The error handler can abort the parsing of a schema immediately by throwing SAXException from the handler. Or for example it can print an error to the screen and try to continue the processing by returning normally from the ErrorHandler
If any Throwable
(or instances of its derived classes)
is thrown from an ErrorHandler
,
the caller of the newSchema
method will be thrown
the same Throwable
object.
SchemaFactory is not allowed to throw SAXException without first reporting it to ErrorHandler .
Applications can call this method even during a Schema is being parsed.
When the ErrorHandler is null, the implementation will behave as if the following ErrorHandler is set:
class DraconianErrorHandler implements ErrorHandler { public void fatalError( org.xml.sax.SAXParseException e ) throws SAXException { throw e; } public void error( org.xml.sax.SAXParseException e ) throws SAXException { throw e; } public void warning( org.xml.sax.SAXParseException e ) throws SAXException { // noop } }
When a new SchemaFactory object is created, initially this field is set to null. This field will NOT be inherited to Schema s, Validator s, or ValidatorHandler s that are created from this SchemaFactory .
Feature can be used to control the way a SchemaFactory parses schemas, although SchemaFactory s are not required to recognize any specific feature names.
The feature name is any fully-qualified URI. It is possible for a SchemaFactory to expose a feature value but to be unable to change the current value.
All implementations are required to support the javax.xml.XMLConstants#FEATURE_SECURE_PROCESSING feature. When the feature is:
true
: the implementation will limit XML processing to conform to implementation limits.
Examples include enity expansion limits and XML Schema constructs that would consume large amounts of resources.
If XML processing is limited for security reasons, it will be reported via a call to the registered
.
See
.
false
: the implementation will processing XML according to the XML specifications without
regard to possible implementation limits.
The property name is any fully-qualified URI. It is possible for a SchemaFactory to recognize a property name but to be unable to change the current value.
SchemaFactory s are not required to recognize setting any specific property names.
SchemaFactory uses a LSResourceResolver when it needs to locate external resources while parsing schemas, although exactly what constitutes "locating external resources" is up to each schema language. For example, for W3C XML Schema, this includes files <include>d or <import>ed, and DTD referenced from schema files, etc.
Applications can call this method even during a Schema is being parsed.
When the LSResourceResolver is null, the implementation will behave as if the following LSResourceResolver is set:
class DumbDOMResourceResolver implements LSResourceResolver { public org.w3c.dom.ls.LSInput resolveResource( String publicId, String systemId, String baseURI) { return null; // always return null } }
If a LSResourceResolver
throws a RuntimeException
(or instances of its derived classes),
then the SchemaFactory
will abort the parsing and
the caller of the newSchema
method will receive
the same RuntimeException
.
When a new SchemaFactory object is created, initially this field is set to null. This field will NOT be inherited to Schema s, Validator s, or ValidatorHandler s that are created from this SchemaFactory .
toString
method returns a string that
"textually represents" this object. The result should
be a concise but informative representation that is easy for a
person to read.
It is recommended that all subclasses override this method.
The toString
method for class Object
returns a string consisting of the name of the class of which the
object is an instance, the at-sign character `@
', and
the unsigned hexadecimal representation of the hash code of the
object. In other words, this method returns a string equal to the
value of:
getClass().getName() + '@' + Integer.toHexString(hashCode())
The current thread must own this object's monitor. The thread
releases ownership of this monitor and waits until another thread
notifies threads waiting on this object's monitor to wake up
either through a call to the notify
method or the
notifyAll
method. The thread then waits until it can
re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) { while (<condition does not hold>) obj.wait(); ... // Perform action appropriate to condition }This method should only be called by a thread that is the owner of this object's monitor. See the
notify
method for a
description of the ways in which a thread can become the owner of
a monitor.The current thread must own this object's monitor.
This method causes the current thread (call it T) to place itself in the wait set for this object and then to relinquish any and all synchronization claims on this object. Thread T becomes disabled for thread scheduling purposes and lies dormant until one of four things happens:
A thread can also wake up without being notified, interrupted, or timing out, a so-called spurious wakeup. While this will rarely occur in practice, applications must guard against it by testing for the condition that should have caused the thread to be awakened, and continuing to wait if the condition is not satisfied. In other words, waits should always occur in loops, like this one:
synchronized (obj) { while (<condition does not hold>) obj.wait(timeout); ... // Perform action appropriate to condition }(For more information on this topic, see Section 3.2.3 in Doug Lea's "Concurrent Programming in Java (Second Edition)" (Addison-Wesley, 2000), or Item 50 in Joshua Bloch's "Effective Java Programming Language Guide" (Addison-Wesley, 2001).
If the current thread is interrupted by another thread while it is waiting, then an InterruptedException is thrown. This exception is not thrown until the lock status of this object has been restored as described above.
Note that the wait method, as it places the current thread into the wait set for this object, unlocks only this object; any other objects on which the current thread may be synchronized remain locked while the thread waits.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify
method for a
description of the ways in which a thread can become the owner of
a monitor.
This method is similar to the wait
method of one
argument, but it allows finer control over the amount of time to
wait for a notification before giving up. The amount of real time,
measured in nanoseconds, is given by:
1000000*timeout+nanos
In all other respects, this method does the same thing as the method of one argument. In particular, wait(0, 0) means the same thing as wait(0).
The current thread must own this object's monitor. The thread releases ownership of this monitor and waits until either of the following two conditions has occurred:
notify
method
or the notifyAll
method.
timeout
milliseconds plus nanos
nanoseconds arguments, has
elapsed.
The thread then waits until it can re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) { while (<condition does not hold>) obj.wait(timeout, nanos); ... // Perform action appropriate to condition }This method should only be called by a thread that is the owner of this object's monitor. See the
notify
method for a
description of the ways in which a thread can become the owner of
a monitor.