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java.lang.Objectorg.modeshape.jcr.api.sequencer.Sequencer
org.modeshape.sequencer.image.ImageMetadataSequencer
public class ImageMetadataSequencer
A sequencer that processes the binary content of an image file, extracts the metadata for the image, and then writes that image metadata to the repository.
This sequencer produces data that corresponds to the following structure:
image:metadata
This structure could be extended in the future to add EXIF and IPTC metadata as child nodes. For example, EXIF metadata is structured as tags in directories, where the directories form something like namespaces, and which are used by different camera vendors to store custom metadata. This structure could be mapped with each directory (e.g. "EXIF" or "Nikon Makernote" or "IPTC") as the name of a child node, with the EXIF tags values stored as either properties or child nodes.
Nested Class Summary |
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Nested classes/interfaces inherited from class org.modeshape.jcr.api.sequencer.Sequencer |
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Sequencer.Context |
Constructor Summary | |
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ImageMetadataSequencer()
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Method Summary | |
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boolean |
execute(Property inputProperty,
Node outputNode,
Sequencer.Context context)
Execute the sequencing operation on the specified property, which has recently been created or changed. |
void |
initialize(NamespaceRegistry registry,
NodeTypeManager nodeTypeManager)
Initialize the sequencer. |
Methods inherited from class org.modeshape.jcr.api.sequencer.Sequencer |
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getAcceptedMimeTypes, getLogger, getName, getPathExpressions, getRepositoryName, getUniqueId, hasAcceptedMimeTypes, isAccepted, registerDefaultMimeTypes, registerNamespace, registerNodeTypes, registerNodeTypes, toString |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Constructor Detail |
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public ImageMetadataSequencer()
Method Detail |
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public boolean execute(Property inputProperty, Node outputNode, Sequencer.Context context) throws Exception
Sequencer
Each sequencer is expected to process the value of the property, extract information from the value, and write a structured representation (in the form of a node or a subgraph of nodes) using the supplied output node. Note that the output node will either be:
Node.setPrimaryType(String)
)The implementation is expected to always clean up all resources that it acquired, even in the case of exceptions.
Note: This method must be threadsafe: ModeShape will likely invoke this method concurrently in separate threads,
and the method should never modify the state or fields of the Sequencer implementation class. All initialization should be
performed in Sequencer.initialize(NamespaceRegistry, NodeTypeManager)
.
execute
in class Sequencer
inputProperty
- the property that was changed and that should be used as the input; never nulloutputNode
- the node that represents the output for the derived information; never null, and will either be
new
if the output is being placed outside of the selected node, or will not be new when the
output is to be placed on the selected input nodecontext
- the context in which this sequencer is executing, and which may contain additional parameters useful when
generating the output structure; never null
Exception
- if there was a problem with the sequencer that could not be handled. All exceptions will be logged
automatically as errors by ModeShape.public void initialize(NamespaceRegistry registry, NodeTypeManager nodeTypeManager) throws RepositoryException, IOException
Sequencer
By default this method does nothing, so it should be overridden by implementations to do a one-time initialization of any
internal components. For example, sequencers can use the supplied registry
and nodeTypeManager
objects to register custom namesapces and node types required by the generated content.
initialize
in class Sequencer
registry
- the namespace registry that can be used to register custom namespaces; never nullnodeTypeManager
- the node type manager that can be used to register custom node types; never null
RepositoryException
- if operations on the NamespaceRegistry
or NodeTypeManager
fail
IOException
- if any stream based operations fail (like importing cnd files)
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