javax.xml.validation

Class SchemaFactory

public abstract class SchemaFactory extends Object

Factory that creates {@link Schema} objects. Entry-point to the validation API.

{@link SchemaFactory} is a schema compiler. It reads external representations of schemas and prepares them for validation.

The {@link 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 {@link SchemaFactory} object at any given moment. Implementations are encouraged to mark methods as synchronized to protect themselves from broken clients.

{@link 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.

Schema Language

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 {@link 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
{@link javax.xml.XMLConstants#W3C_XML_SCHEMA_NS_URI} ("http://www.w3.org/2001/XMLSchema") W3C XML Schema 1.0
{@link javax.xml.XMLConstants#RELAXNG_NS_URI} ("http://relaxng.org/ns/structure/1.0") RELAX NG 1.0

Since: 1.5

Version: $Revision: 226183 $, $Date: 2005-04-08 06:39:14 -0400 (Fri, 08 Apr 2005) $

Author: Kohsuke Kawaguchi

Constructor Summary
protected SchemaFactory()

Constructor for derived classes.

The constructor does nothing.

Derived classes must create {@link SchemaFactory} objects that have null {@link ErrorHandler} and null {@link LSResourceResolver}.

Method Summary
abstract ErrorHandlergetErrorHandler()
Gets the current {@link ErrorHandler} set to this {@link SchemaFactory}.
booleangetFeature(String name)
Look up the value of a feature flag.
ObjectgetProperty(String name)
Look up the value of a property.
abstract LSResourceResolvergetResourceResolver()
Gets the current {@link LSResourceResolver} set to this {@link SchemaFactory}.
abstract booleanisSchemaLanguageSupported(String schemaLanguage)

Is specified schema supported by this SchemaFactory?

static SchemaFactorynewInstance(String schemaLanguage)

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:

  1. If the system property "javax.xml.validation.SchemaFactory:schemaLanguage" is present (where schemaLanguage is the parameter to this method), then its value is read as a class name.
SchemanewSchema(Source schema)

Parses the specified source as a schema and returns it as a schema.

This is a convenience method for {@link #newSchema(Source[] schemas)}.

SchemanewSchema(File schema)

Parses the specified File as a schema and returns it as a Schema.

This is a convenience method for {@link #newSchema(Source schema)}.

SchemanewSchema(URL schema)

Parses the specified URL as a schema and returns it as a Schema.

This is a convenience method for {@link #newSchema(Source schema)}.

abstract SchemanewSchema(Source[] schemas)
Parses the specified source(s) as a schema and returns it as a schema.
abstract SchemanewSchema()
Creates a special {@link Schema} object.
abstract voidsetErrorHandler(ErrorHandler errorHandler)
Sets the {@link ErrorHandler} to receive errors encountered during the newSchema method invocation.
voidsetFeature(String name, boolean value)
Set the value of a feature flag.
voidsetProperty(String name, Object object)
Set the value of a property.
abstract voidsetResourceResolver(LSResourceResolver resourceResolver)
Sets the {@link LSResourceResolver} to customize resource resolution when parsing schemas.

Constructor Detail

SchemaFactory

protected SchemaFactory()

Constructor for derived classes.

The constructor does nothing.

Derived classes must create {@link SchemaFactory} objects that have null {@link ErrorHandler} and null {@link LSResourceResolver}.

Method Detail

getErrorHandler

public abstract ErrorHandler getErrorHandler()
Gets the current {@link ErrorHandler} set to this {@link SchemaFactory}.

Returns: This method returns the object that was last set through the {@link #setErrorHandler(ErrorHandler)} method, or null if that method has never been called since this {@link SchemaFactory} has created.

See Also: setErrorHandler

getFeature

public boolean getFeature(String name)
Look up the value of a feature flag.

The feature name is any fully-qualified URI. It is possible for a {@link 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.

Parameters: name The feature name, which is a non-null fully-qualified URI.

Returns: The current value of the feature (true or false).

Throws: org.xml.sax.SAXNotRecognizedException If the feature value can't be assigned or retrieved. org.xml.sax.SAXNotSupportedException When the {@link SchemaFactory} recognizes the feature name but cannot determine its value at this time. NullPointerException if the name parameter is null.

See Also: SchemaFactory

getProperty

public Object getProperty(String name)
Look up the value of a property.

The property name is any fully-qualified URI. It is possible for a {@link SchemaFactory} to recognize a property name but temporarily be unable to return its value.

{@link 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.

Parameters: name The property name, which is a non-null fully-qualified URI.

Returns: The current value of the property.

Throws: org.xml.sax.SAXNotRecognizedException If the property value can't be assigned or retrieved. org.xml.sax.SAXNotSupportedException When the XMLReader recognizes the property name but cannot determine its value at this time. NullPointerException if the name parameter is null.

See Also: SchemaFactory

getResourceResolver

public abstract LSResourceResolver getResourceResolver()
Gets the current {@link LSResourceResolver} set to this {@link SchemaFactory}.

Returns: This method returns the object that was last set through the {@link #setResourceResolver(LSResourceResolver)} method, or null if that method has never been called since this {@link SchemaFactory} has created.

See Also: setErrorHandler

isSchemaLanguageSupported

public abstract boolean isSchemaLanguageSupported(String schemaLanguage)

Is specified schema supported by this SchemaFactory?

Parameters: schemaLanguage Specifies the schema language which the returned SchemaFactory will understand. schemaLanguage must specify a valid schema language.

Returns: true if SchemaFactory supports schemaLanguage, else false.

Throws: NullPointerException If schemaLanguage is null. IllegalArgumentException If schemaLanguage.length() == 0 or schemaLanguage does not specify a valid schema language.

newInstance

public static final SchemaFactory newInstance(String schemaLanguage)

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:

  1. If the system property "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.
  2. $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.
  3. 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:

            {@link #isSchemaLanguageSupported(String schemaLanguage)}
         
    The first service provider found in class loader order that supports the specified schema language is returned.
  4. Platform default SchemaFactory is located in a implementation specific way. There must be a platform default SchemaFactory for W3C XML Schema.

If everything fails, {@link IllegalArgumentException} will be thrown.

Tip for Trouble-shooting:

See {@link java.util.Properties#load(java.io.InputStream)} 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
 

Parameters: schemaLanguage Specifies the schema language which the returned SchemaFactory will understand. See the list of available schema languages for the possible values.

Returns: New instance of a SchemaFactory

Throws: IllegalArgumentException If no implementation of the schema language is available. NullPointerException If the schemLanguage parameter is null.

newSchema

public Schema newSchema(Source schema)

Parses the specified source as a schema and returns it as a schema.

This is a convenience method for {@link #newSchema(Source[] schemas)}.

Parameters: schema Source that represents a schema.

Returns: New Schema from parsing schema.

Throws: SAXException If a SAX error occurs during parsing. NullPointerException if schema is null.

newSchema

public Schema newSchema(File schema)

Parses the specified File as a schema and returns it as a Schema.

This is a convenience method for {@link #newSchema(Source schema)}.

Parameters: schema File that represents a schema.

Returns: New Schema from parsing schema.

Throws: SAXException If a SAX error occurs during parsing. NullPointerException if schema is null.

newSchema

public Schema newSchema(URL schema)

Parses the specified URL as a schema and returns it as a Schema.

This is a convenience method for {@link #newSchema(Source schema)}.

Parameters: schema URL that represents a schema.

Returns: New Schema from parsing schema.

Throws: SAXException If a SAX error occurs during parsing. NullPointerException if schema is null.

newSchema

public abstract Schema newSchema(Source[] schemas)
Parses the specified source(s) as a schema and returns it as a schema.

The callee will read all the {@link Source}s and combine them into a single schema. The exact semantics of the combination depends on the schema language that this {@link SchemaFactory} object is created for.

When an {@link 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.

W3C XML Schema 1.0

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 {@link ErrorHandler}.

RELAX NG

For RELAX NG, this method must throw {@link UnsupportedOperationException} if schemas.length!=1.

Parameters: schemas inputs to be parsed. {@link SchemaFactory} is required to recognize {@link javax.xml.transform.sax.SAXSource}, {@link StreamSource}, and {@link javax.xml.transform.dom.DOMSource}.

Returns: Always return a non-null valid {@link Schema} object. Note that when an error has been reported, there is no guarantee that the returned {@link Schema} object is meaningful.

Throws: SAXException If an error is found during processing the specified inputs. When an {@link ErrorHandler} is set, errors are reported to there first. See {@link #setErrorHandler(ErrorHandler)}. NullPointerException If the schemas parameter itself is null or any item in the array is null. IllegalArgumentException If any item in the array is not recognized by this method. UnsupportedOperationException If the schema language doesn't support this operation.

newSchema

public abstract Schema newSchema()
Creates a special {@link Schema} object.

The exact semantics of the returned {@link Schema} object depends on the schema language that this {@link SchemaFactory} is created for.

Also, implementations are allowed to use implementation-specific property/feature to alter the semantics of this method.

W3C XML Schema 1.0

For XML Schema, this method creates a {@link Schema} object that performs validation by using location hints specified in documents.

The returned {@link 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

RELAX NG does not support this operation.

Returns: Always return non-null valid {@link Schema} object.

Throws: UnsupportedOperationException If this operation is not supported by the callee. SAXException If this operation is supported but failed for some reason.

setErrorHandler

public abstract void setErrorHandler(ErrorHandler errorHandler)
Sets the {@link ErrorHandler} to receive errors encountered during the newSchema method invocation.

Error handler can be used to customize the error handling process during schema parsing. When an {@link ErrorHandler} is set, errors found during the parsing of schemas will be first sent to the {@link ErrorHandler}.

The error handler can abort the parsing of a schema immediately by throwing {@link 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 {@link ErrorHandler}

If any {@link Throwable} (or instances of its derived classes) is thrown from an {@link ErrorHandler}, the caller of the newSchema method will be thrown the same {@link Throwable} object.

{@link SchemaFactory} is not allowed to throw {@link SAXException} without first reporting it to {@link ErrorHandler}.

Applications can call this method even during a {@link Schema} is being parsed.

When the {@link ErrorHandler} is null, the implementation will behave as if the following {@link ErrorHandler} is set:

 class DraconianErrorHandler implements {@link ErrorHandler} {
     public void fatalError( {@link org.xml.sax.SAXParseException} e ) throws {@link SAXException} {
         throw e;
     }
     public void error( {@link org.xml.sax.SAXParseException} e ) throws {@link SAXException} {
         throw e;
     }
     public void warning( {@link org.xml.sax.SAXParseException} e ) throws {@link SAXException} {
         // noop
     }
 }
 

When a new {@link SchemaFactory} object is created, initially this field is set to null. This field will NOT be inherited to {@link Schema}s, {@link Validator}s, or {@link ValidatorHandler}s that are created from this {@link SchemaFactory}.

Parameters: errorHandler A new error handler to be set. This parameter can be null.

setFeature

public void setFeature(String name, boolean value)
Set the value of a feature flag.

Feature can be used to control the way a {@link SchemaFactory} parses schemas, although {@link SchemaFactory}s are not required to recognize any specific feature names.

The feature name is any fully-qualified URI. It is possible for a {@link SchemaFactory} to expose a feature value but to be unable to change the current value.

All implementations are required to support the {@link javax.xml.XMLConstants#FEATURE_SECURE_PROCESSING} feature. When the feature is:

Parameters: name The feature name, which is a non-null fully-qualified URI. value The requested value of the feature (true or false).

Throws: org.xml.sax.SAXNotRecognizedException If the feature value can't be assigned or retrieved. org.xml.sax.SAXNotSupportedException When the {@link SchemaFactory} recognizes the feature name but cannot set the requested value. NullPointerException if the name parameter is null.

See Also: getFeature

setProperty

public void setProperty(String name, Object object)
Set the value of a property.

The property name is any fully-qualified URI. It is possible for a {@link SchemaFactory} to recognize a property name but to be unable to change the current value.

{@link SchemaFactory}s are not required to recognize setting any specific property names.

Parameters: name The property name, which is a non-null fully-qualified URI. object The requested value for the property.

Throws: org.xml.sax.SAXNotRecognizedException If the property value can't be assigned or retrieved. org.xml.sax.SAXNotSupportedException When the {@link SchemaFactory} recognizes the property name but cannot set the requested value. NullPointerException if the name parameter is null.

setResourceResolver

public abstract void setResourceResolver(LSResourceResolver resourceResolver)
Sets the {@link LSResourceResolver} to customize resource resolution when parsing schemas.

{@link SchemaFactory} uses a {@link 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 {@link Schema} is being parsed.

When the {@link LSResourceResolver} is null, the implementation will behave as if the following {@link LSResourceResolver} is set:

 class DumbDOMResourceResolver implements {@link LSResourceResolver} {
     public {@link org.w3c.dom.ls.LSInput} resolveResource(
         String publicId, String systemId, String baseURI) {
         
         return null; // always return null
     }
 }
 

If a {@link LSResourceResolver} throws a {@link RuntimeException} (or instances of its derived classes), then the {@link SchemaFactory} will abort the parsing and the caller of the newSchema method will receive the same {@link RuntimeException}.

When a new {@link SchemaFactory} object is created, initially this field is set to null. This field will NOT be inherited to {@link Schema}s, {@link Validator}s, or {@link ValidatorHandler}s that are created from this {@link SchemaFactory}.

Parameters: resourceResolver A new resource resolver to be set. This parameter can be null.