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SchemaFactory

public abstract class SchemaFactory
extends Object

java.lang.Object
   ↳ javax.xml.validation.SchemaFactory


Factory that creates Schema objects. Entry-point to the validation API.

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.

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 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 implementers 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
W3C_XML_SCHEMA_NS_URI ("http://www.w3.org/2001/XMLSchema") W3C XML Schema 1.0
RELAXNG_NS_URI ("http://relaxng.org/ns/structure/1.0") RELAX NG 1.0

Summary

Protected constructors

SchemaFactory()

Constructor for derived classes.

Public methods

abstract ErrorHandler getErrorHandler()

Gets the current ErrorHandler set to this SchemaFactory.

boolean getFeature(String name)

Look up the value of a feature flag.

Object getProperty(String name)

Look up the value of a property.

abstract LSResourceResolver getResourceResolver()

Gets the current LSResourceResolver set to this SchemaFactory.

abstract boolean isSchemaLanguageSupported(String schemaLanguage)

Is specified schema supported by this SchemaFactory?

static SchemaFactory newInstance(String schemaLanguage, String factoryClassName, ClassLoader classLoader)

Returns an instance of the named implementation of SchemaFactory.

static SchemaFactory newInstance(String schemaLanguage)

Lookup an implementation of the SchemaFactory that supports the specified schema language and return it.

Schema newSchema(File schema)

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

Schema newSchema(Source schema)

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

abstract Schema newSchema()

Creates a special Schema object.

abstract Schema newSchema(Source[] schemas)

Parses the specified source(s) as a schema and returns it as a schema.

Schema newSchema(URL schema)

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

abstract void setErrorHandler(ErrorHandler errorHandler)

Sets the ErrorHandler to receive errors encountered during the newSchema method invocation.

void setFeature(String name, boolean value)

Set the value of a feature flag.

void setProperty(String name, Object object)

Set the value of a property.

abstract void setResourceResolver(LSResourceResolver resourceResolver)

Sets the LSResourceResolver to customize resource resolution when parsing schemas.

Inherited methods

From class java.lang.Object

Protected constructors

SchemaFactory

Added in API level 8
SchemaFactory ()

Constructor for derived classes.

The constructor does nothing.

Derived classes must create SchemaFactory objects that have null ErrorHandler and null LSResourceResolver.

Public methods

getErrorHandler

Added in API level 8
ErrorHandler getErrorHandler ()

Gets the current ErrorHandler set to this SchemaFactory.

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

See also:

getFeature

Added in API level 8
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 SchemaFactory to recognize a feature name but temporarily be unable to return its value.

Implementers are free (and encouraged) to invent their own features, using names built on their own URIs.

Parameters
name String: The feature name, which is a non-null fully-qualified URI.
Returns
boolean The current value of the feature (true or false).
Throws
SAXNotRecognizedException If the feature value can't be assigned or retrieved.
SAXNotSupportedException When the SchemaFactory recognizes the feature name but cannot determine its value at this time.
NullPointerException if the name parameter is null.

See also:

getProperty

Added in API level 8
Object getProperty (String name)

Look up the value of a property.

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.

SchemaFactorys are not required to recognize any specific property names.

Implementers are free (and encouraged) to invent their own properties, using names built on their own URIs.

Parameters
name String: The property name, which is a non-null fully-qualified URI.
Returns
Object The current value of the property.
Throws
SAXNotRecognizedException If the property value can't be assigned or retrieved.
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:

getResourceResolver

Added in API level 8
LSResourceResolver getResourceResolver ()

Gets the current LSResourceResolver set to this SchemaFactory.

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

See also:

isSchemaLanguageSupported

Added in API level 8
boolean isSchemaLanguageSupported (String schemaLanguage)

Is specified schema supported by this SchemaFactory?

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

Added in API level 9
SchemaFactory newInstance (String schemaLanguage, 
                String factoryClassName, 
                ClassLoader classLoader)

Returns an instance of the named implementation of SchemaFactory.

Parameters
schemaLanguage String
factoryClassName String
classLoader ClassLoader
Returns
SchemaFactory
Throws
IllegalArgumentException if factoryClassName is not available, cannot be instantiated, or doesn't support schemaLanguage.

newInstance

Added in API level 8
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:

            isSchemaLanguageSupported(String)
         
    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, IllegalArgumentException will be thrown.

Tip for Trouble-shooting:

See 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 String: Specifies the schema language which the returned SchemaFactory will understand. See the list of available schema languages for the possible values.
Returns
SchemaFactory New instance of a SchemaFactory
Throws
IllegalArgumentException If no implementation of the schema language is available.
NullPointerException If the schemaLanguage parameter is null.

newSchema

Added in API level 8
Schema newSchema (File schema)

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

This is a convenience method for newSchema(Source).

Parameters
schema File: File that represents a schema.
Returns
Schema New Schema from parsing schema.
Throws
SAXException If a SAX error occurs during parsing.
NullPointerException if schema is null.

newSchema

Added in API level 8
Schema newSchema (Source schema)

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

This is a convenience method for newSchema(Source[]).

Parameters
schema Source: Source that represents a schema.
Returns
Schema New Schema from parsing schema.
Throws
SAXException If a SAX error occurs during parsing.
NullPointerException if schema is null.

newSchema

Added in API level 8
Schema newSchema ()

Creates a special Schema object.

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.

W3C XML Schema 1.0

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 assumption 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
Schema Always return non-null valid Schema object.
Throws
UnsupportedOperationException If this operation is not supported by the callee.
SAXException If this operation is supported but failed for some reason.

newSchema

Added in API level 8
Schema newSchema (Source[] schemas)

Parses the specified source(s) as a schema and returns it as a schema.

The callee will read all the Sources 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.

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 behavior 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.

RELAX NG

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

Parameters
schemas Source: inputs to be parsed. SchemaFactory is required to recognize StreamSource, SAXSource, and DOMSource.
Returns
Schema Always return a non-null valid Schema object. Note that when an error has been reported, there is no guarantee that the returned Schema object is meaningful.
Throws
SAXException If an error is found during processing the specified inputs. When an ErrorHandler is set, errors are reported to there first. See 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

Added in API level 8
Schema newSchema (URL schema)

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

This is a convenience method for newSchema(Source).

Parameters
schema URL: URL that represents a schema.
Returns
Schema New Schema from parsing schema.
Throws
SAXException If a SAX error occurs during parsing.
NullPointerException if schema is null.

setErrorHandler

Added in API level 8
void setErrorHandler (ErrorHandler errorHandler)

Sets the 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 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( SAXParseException e ) throws SAXException {
         throw e;
     }
     public void error( SAXParseException e ) throws SAXException {
         throw e;
     }
     public void warning( 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 Schemas, Validators, or ValidatorHandlers that are created from this SchemaFactory.

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

setFeature

Added in API level 8
void setFeature (String name, 
                boolean value)

Set the value of a feature flag.

Feature can be used to control the way a SchemaFactory parses schemas, although SchemaFactorys 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 FEATURE_SECURE_PROCESSING feature. When the feature is:

  • true: the implementation will limit XML processing to conform to implementation limits. Examples include entity 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 fatalError(org.xml.sax.SAXParseException). See setErrorHandler(ErrorHandler).
  • false: the implementation will processing XML according to the XML specifications without regard to possible implementation limits.

Parameters
name String: The feature name, which is a non-null fully-qualified URI.
value boolean: The requested value of the feature (true or false).
Throws
SAXNotRecognizedException If the feature value can't be assigned or retrieved.
SAXNotSupportedException When the SchemaFactory recognizes the feature name but cannot set the requested value.
NullPointerException if the name parameter is null.

See also:

setProperty

Added in API level 8
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 SchemaFactory to recognize a property name but to be unable to change the current value.

SchemaFactorys are not required to recognize setting any specific property names.

Parameters
name String: The property name, which is a non-null fully-qualified URI.
object Object: The requested value for the property.
Throws
SAXNotRecognizedException If the property value can't be assigned or retrieved.
SAXNotSupportedException When the SchemaFactory recognizes the property name but cannot set the requested value.
NullPointerException if the name parameter is null.

setResourceResolver

Added in API level 8
void setResourceResolver (LSResourceResolver resourceResolver)

Sets the LSResourceResolver to customize resource resolution when parsing schemas.

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 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 Schemas, Validators, or ValidatorHandlers that are created from this SchemaFactory.

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