it.unimi.di.mg4j.document
Class DispatchingDocumentFactory

java.lang.Object
  it.unimi.di.mg4j.document.AbstractDocumentFactory
      it.unimi.di.mg4j.document.PropertyBasedDocumentFactory
          it.unimi.di.mg4j.document.DispatchingDocumentFactory

All Implemented Interfaces:

DocumentFactory, FlyweightPrototype<DocumentFactory>, Serializable

public class DispatchingDocumentFactory
extends PropertyBasedDocumentFactory

A document factory that actually dispatches the task of building documents to various factories according to some strategy.

The strategy is specified as (an object embedding) a method that determines which factory should be used on the basis of the metadata that are provided to the getDocument(InputStream, Reference2ObjectMap) method. Since usually the strategy will have to resolve the name of metadata, it is also passed this factory, so that the correct PropertyBasedDocumentFactory.resolve(Enum,Reference2ObjectMap) method can be invoked.

Moreover, at construction one must specify, for each subfactory and for each field of this factory, which field of the subfactory should be used. Note that to guarantee sequential access, fields specified for each subfactory should appear in increasing order.

See Also:

Serialized Form

Nested Class Summary

static interface	DispatchingDocumentFactory.DispatchingStrategy A strategy that decides which factory is appropriate using the document metadata.
static class	DispatchingDocumentFactory.MetadataKeys Case-insensitive keys for metadata.
static class	DispatchingDocumentFactory.StringBasedDispatchingStrategy A strategy that is based on trying to match the value of the metadata with a given key with respect to a certain set of values.

Nested classes/interfaces inherited from interface it.unimi.di.mg4j.document.DocumentFactory

DocumentFactory.FieldType

Field Summary

static String

OTHERWISE_IN_RULE The value to be used in RULE to introduce the default factory.

Fields inherited from class it.unimi.di.mg4j.document.PropertyBasedDocumentFactory

defaultMetadata

Constructor Summary

DispatchingDocumentFactory()

DispatchingDocumentFactory(DocumentFactory[] documentFactory, String[] fieldName, DocumentFactory.FieldType[] fieldType, int[][] rename, DispatchingDocumentFactory.DispatchingStrategy strategy)
Creates a new dispatching factory.

DispatchingDocumentFactory(Properties properties)

DispatchingDocumentFactory(Reference2ObjectMap<Enum<?>,Object> defaultMetadata)

DispatchingDocumentFactory(String[] property)

Method Summary

DispatchingDocumentFactory	copy()
int	fieldIndex(String fieldName) Returns the index of a field, given its symbolic name.
String	fieldName(int field) Returns the symbolic name of a field.
DocumentFactory.FieldType	fieldType(int field) Returns the type of a field.
Document	getDocument(InputStream rawContent, Reference2ObjectMap<Enum<?>,Object> metadata) Returns the document obtained by parsing the given byte stream.
static void	main(String[] arg)
int	numberOfFields() Returns the number of fields present in the documents produced by this factory.
protected boolean	parseProperty(String key, String[] values, Reference2ObjectMap<Enum<?>,Object> metadata) Parses a property with given key and value, adding it to the given map.

Methods inherited from class it.unimi.di.mg4j.document.PropertyBasedDocumentFactory

ensureJustOne, getInstance, getInstance, getInstance, getInstance, parseProperties, parseProperties, resolve, resolve, resolveNotNull, sameKey

Methods inherited from class it.unimi.di.mg4j.document.AbstractDocumentFactory

ensureFieldIndex, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

OTHERWISE_IN_RULE

public static final String OTHERWISE_IN_RULE

The value to be used in RULE to introduce the default factory. Otherwise, no default factory is provided for documents that do not match.

See Also:

Constant Field Values

Constructor Detail

DispatchingDocumentFactory

public DispatchingDocumentFactory(DocumentFactory[] documentFactory,
                                  String[] fieldName,
                                  DocumentFactory.FieldType[] fieldType,
                                  int[][] rename,
                                  DispatchingDocumentFactory.DispatchingStrategy strategy)

Creates a new dispatching factory.

Parameters:

documentFactory - the array of subfactories.

fieldName - the names of this factory's fields.

fieldType - the types of this factory's fields.

rename - the way fields of this class are mapped to fields of the subfactories.

strategy - the strategy to decide which factory should be used.

DispatchingDocumentFactory

public DispatchingDocumentFactory(Properties properties)
                           throws ConfigurationException

Throws:

ConfigurationException

DispatchingDocumentFactory

public DispatchingDocumentFactory(String[] property)
                           throws ConfigurationException

Throws:

ConfigurationException

DispatchingDocumentFactory

public DispatchingDocumentFactory(Reference2ObjectMap<Enum<?>,Object> defaultMetadata)

DispatchingDocumentFactory

public DispatchingDocumentFactory()

Method Detail

copy

public DispatchingDocumentFactory copy()

parseProperty

protected boolean parseProperty(String key,
                                String[] values,
                                Reference2ObjectMap<Enum<?>,Object> metadata)
                         throws ConfigurationException

Description copied from class: PropertyBasedDocumentFactory

Parses a property with given key and value, adding it to the given map.

Currently this implementation just parses the PropertyBasedDocumentFactory.MetadataKeys.LOCALE property.

Subclasses should do their own parsing, returing true in case of success and returning super.parseProperty() otherwise.

Overrides:

parseProperty in class PropertyBasedDocumentFactory

Parameters:

key - the property key.

values - the property value; this is an array, because properties may have a list of comma-separated values.

metadata - the metadata map.

Returns:

true if the property was parsed correctly, false if it was ignored.

Throws:

ConfigurationException

numberOfFields

public int numberOfFields()

Description copied from interface: DocumentFactory

Returns the number of fields present in the documents produced by this factory.

Returns:

the number of fields present in the documents produced by this factory.

fieldName

public String fieldName(int field)

Description copied from interface: DocumentFactory

Returns the symbolic name of a field.

Parameters:

field - the index of a field (between 0 inclusive and DocumentFactory.numberOfFields() exclusive}).

Returns:

the symbolic name of the field-th field.

fieldIndex

public int fieldIndex(String fieldName)

Description copied from interface: DocumentFactory

Returns the index of a field, given its symbolic name.

Parameters:

fieldName - the name of a field of this factory.

Returns:

the corresponding index, or -1 if there is no field with name fieldName.

fieldType

public DocumentFactory.FieldType fieldType(int field)

Description copied from interface: DocumentFactory

Returns the type of a field.

The possible types are defined in DocumentFactory.FieldType.

Parameters:

field - the index of a field (between 0 inclusive and DocumentFactory.numberOfFields() exclusive}).

Returns:

the type of the field-th field.

getDocument

public Document getDocument(InputStream rawContent,
                            Reference2ObjectMap<Enum<?>,Object> metadata)
                     throws IOException

Description copied from interface: DocumentFactory

Returns the document obtained by parsing the given byte stream.

The parameter metadata actually replaces the lack of a simple keyword-based parameter-passing system in Java. This method might take several different type of “suggestions” which have been collected by the collection: typically, the document title, a URI representing the document, its MIME type, its encoding and so on. Some of this information might be set by default (as it happens, for instance, in a PropertyBasedDocumentFactory). Implementations of this method must consult the metadata provided by the collection, possibly complete them with default factory metadata, and proceed to the document construction.

Parameters:

rawContent - the raw content from which the document should be extracted; it must not be closed, as resource management is a responsibility of the DocumentCollection.

metadata - a map from enums (e.g., keys taken in PropertyBasedDocumentFactory) to various kind of objects.

Returns:

the document obtained by parsing the given character sequence.

Throws:

IOException

main

public static void main(String[] arg)
                 throws IOException,
                        ConfigurationException

Throws:

IOException

ConfigurationException