org.alfresco.repo.content.metadata.xml

Class XPathMetadataExtracter

java.lang.Object

org.alfresco.repo.content.metadata.AbstractMappingMetadataExtracter

org.alfresco.repo.content.metadata.xml.XPathMetadataExtracter

All Implemented Interfaces:

NamespaceContext, ContentWorker, MetadataEmbedder, MetadataExtracter, org.springframework.beans.factory.Aware, org.springframework.beans.factory.BeanNameAware, org.springframework.context.ApplicationContextAware

public class XPathMetadataExtracter
extends AbstractMappingMetadataExtracter
implements NamespaceContext

An extracter that pulls values from XML documents using configurable XPath statements. It is not possible to list a default set of mappings - this is down to the configuration only.

When an instance of this extracter is configured, XPath statements should be provided to extract all the available metadata. The implementation is sensitive to what is actually requested by the configured mapping and will only perform the queries necessary to fulfill the requirements.

To summarize, there are two configurations required for this class:

• A mapping of all reasonable document properties to XPath statements. See AbstractMappingMetadataExtracter.setMappingProperties(java.util.Properties).
• A mapping of document property names to Alfresco repository model QNames. See setXpathMappingProperties(Properties).

All values are extracted as text values and therefore all XPath statements must evaluate to a node that can be rendered as text.

Since:

2.1

Author:

Derek Hulley

See Also:

AbstractMappingMetadataExtracter.setMappingProperties(Properties), setXpathMappingProperties(Properties)

Nested Class Summary

Nested classes/interfaces inherited from interface org.alfresco.repo.content.metadata.MetadataExtracter

MetadataExtracter.OverwritePolicy

Field Summary

Fields

Modifier and Type	Field and Description
static String[]	SUPPORTED_MIMETYPES

Fields inherited from class org.alfresco.repo.content.metadata.AbstractMappingMetadataExtracter

MEGABYTE_SIZE, metadataExtracterConfig, NAMESPACE_PROPERTY_PREFIX, PROPERTY_COMPONENT_EMBED, PROPERTY_COMPONENT_EXTRACT, PROPERTY_PREFIX_METADATA

Constructor Summary

Constructors

Constructor and Description
XPathMetadataExtracter() Default constructor

Method Summary

Modifier and Type	Method and Description
protected Map<String,Serializable>	extractRaw(org.alfresco.service.cmr.repository.ContentReader reader) Override to provide the raw extracted metadata values.
protected Map<String,Set<org.alfresco.service.namespace.QName>>	getDefaultMapping() It is not possible to have any default mappings, but something has to be returned.
String	getNamespaceURI(String prefix)
String	getPrefix(String namespaceURI)
Iterator	getPrefixes(String namespaceURI)
protected void	init() Provides a hook point for implementations to perform initialization.
protected Map<String,Serializable>	processDocument(Document document) Executes all the necessary XPath statements to extract values.
protected void	readXPathMappingProperties(Properties xpathMappingProperties) A utility method to convert mapping properties to the Map form.
void	setXpathMappingProperties(Properties xpathMappingProperties) Set the properties file that maps document properties to the XPath statements necessary to retrieve them.

Methods inherited from class org.alfresco.repo.content.metadata.AbstractMappingMetadataExtracter

checkIsEmbedSupported, checkIsSupported, embed, embedInternal, extract, extract, extract, filterSystemProperties, getBeanName, getDefaultEmbedMapping, getEmbedMapping, getExecutorService, getLimits, getMapping, getMimetypeService, isEmbeddingSupported, isSupported, makeDate, newRawMap, putRawValue, readEmbedMappingProperties, readEmbedMappingProperties, readGlobalEmbedMappingProperties, readGlobalExtractMappingProperties, readMappingProperties, readMappingProperties, register, setApplicationContext, setBeanName, setDictionaryService, setEmbedMapping, setEmbedMappingProperties, setEnableStringTagging, setExecutorService, setFailOnTypeConversion, setInheritDefaultEmbedMapping, setInheritDefaultMapping, setMapping, setMappingProperties, setMetadataExtracterConfig, setMimetypeLimits, setMimetypeService, setOverwritePolicy, setProperties, setRegistry, setSupportedDateFormats, setSupportedEmbedMimetypes, setSupportedMimetypes

Methods inherited from class java.lang.Object

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

Field Detail

SUPPORTED_MIMETYPES

public static String[] SUPPORTED_MIMETYPES

Constructor Detail

XPathMetadataExtracter

public XPathMetadataExtracter()

Default constructor

Method Detail

getNamespaceURI

public String getNamespaceURI(String prefix)

Specified by:

getNamespaceURI in interface NamespaceContext

getPrefix

public String getPrefix(String namespaceURI)

Specified by:

getPrefix in interface NamespaceContext

getPrefixes

public Iterator getPrefixes(String namespaceURI)

Specified by:

getPrefixes in interface NamespaceContext

setXpathMappingProperties

public void setXpathMappingProperties(Properties xpathMappingProperties)

Set the properties file that maps document properties to the XPath statements necessary to retrieve them.

The Xpath mapping is of the form:

 # Namespaces prefixes
 namespace.prefix.my=http://www....com/alfresco/1.0
 
 # Mapping
 editor=/my:example-element/@cm:editor
 title=/my:example-element/text()
 

init

protected void init()

Description copied from class: AbstractMappingMetadataExtracter

Provides a hook point for implementations to perform initialization. The base implementation must be invoked or the extracter will fail during extraction. The default mappings will be requested during initialization.

Overrides:

init in class AbstractMappingMetadataExtracter

getDefaultMapping

protected Map<String,Set<org.alfresco.service.namespace.QName>> getDefaultMapping()

It is not possible to have any default mappings, but something has to be returned.

Overrides:

getDefaultMapping in class AbstractMappingMetadataExtracter

Returns:

Returns an empty map

See Also:

AbstractMappingMetadataExtracter.setInheritDefaultMapping(boolean inherit)

extractRaw

protected Map<String,Serializable> extractRaw(org.alfresco.service.cmr.repository.ContentReader reader)
                                       throws Throwable

Description copied from class: AbstractMappingMetadataExtracter

Override to provide the raw extracted metadata values. An extracter should extract as many of the available properties as is realistically possible. Even if the default mapping doesn't handle all properties, it is possible for each instance of the extracter to be configured differently and more or less of the properties may be used in different installations.

Raw values must not be trimmed or removed for any reason. Null values and empty strings are

• Null: Removed
• Empty String: Passed to the OverwritePolicy
• Non Serializable: Converted to String or fails if that is not possible

Properties extracted and their meanings and types should be thoroughly described in the class-level javadocs of the extracter implementation, for example:

 editor: - the document editor        -->  cm:author
 title:  - the document title         -->  cm:title
 user1:  - the document summary
 user2:  - the document description   -->  cm:description
 user3:  -
 user4:  -
 

Specified by:

extractRaw in class AbstractMappingMetadataExtracter

Parameters:

reader - the document to extract the values from. This stream provided by the reader must be closed if accessed directly.

Returns:

Returns a map of document property values keyed by property name.

Throws:

Throwable - All exception conditions can be handled.

See Also:

AbstractMappingMetadataExtracter.getDefaultMapping()

processDocument

protected Map<String,Serializable> processDocument(Document document)
                                            throws Throwable

Executes all the necessary XPath statements to extract values.

Throws:

Throwable

readXPathMappingProperties

protected void readXPathMappingProperties(Properties xpathMappingProperties)

A utility method to convert mapping properties to the Map form.

See Also:

AbstractMappingMetadataExtracter.setMappingProperties(Properties)