org.geotools.data
Class CachingFeatureSource

java.lang.Object
  extended by org.geotools.data.CachingFeatureSource
All Implemented Interfaces:
FeatureSource

public class CachingFeatureSource
extends java.lang.Object
implements FeatureSource

A caching feature source for fast data access.

This feature source is used as a wrapper offering a spatial index, for a quick user interface experience at the cost of memory.


Constructor Summary
CachingFeatureSource(FeatureSource original)
           
 
Method Summary
 void addFeatureListener(FeatureListener listener)
          Adds a listener to the list that's notified each time a change to the FeatureStore occurs.
 ReferencedEnvelope getBounds()
          Gets the bounding box of this datasource.
 ReferencedEnvelope getBounds(Query query)
          Gets the bounding box of the features that would be returned by this query.
 int getCount(Query query)
          Gets the number of the features that would be returned by this query.
 DataStore getDataStore()
          Access to the DataStore implementing this FeatureStore.
 FeatureCollection getFeatures()
          Loads all features from the datasource into the return FeatureResults.
 FeatureCollection getFeatures(org.opengis.filter.Filter filter)
          Loads features from the datasource into the returned FeatureResults, based on the passed filter.
 FeatureCollection getFeatures(Query query)
          Loads features from the datasource into the returned FeatureResults, based on the passed query.
 ResourceInfo getInfo()
          Information describing the contents of this resoruce.
 org.opengis.feature.type.Name getName()
          Returns the qualified name for the Features this FeatureSource serves.
 QueryCapabilities getQueryCapabilities()
          Returns and indication of what query capabilities this FeatureSource supports natively.
 org.opengis.feature.type.FeatureType getSchema()
          Retrieves the featureType that features extracted from this datasource will be created with.
 java.util.Set getSupportedHints()
          Returns the set of hints this FeatureSource is able to support.
 void removeFeatureListener(FeatureListener listener)
          Removes a listener from the list that's notified each time a change to the FeatureStore occurs.
static org.opengis.feature.simple.SimpleFeature reType(org.opengis.feature.simple.SimpleFeatureType featureType, org.opengis.feature.simple.SimpleFeature feature)
          Same as DataUtilities.reType, but without the cloning that uselessly wastes CPU cycles...
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

CachingFeatureSource

public CachingFeatureSource(FeatureSource original)
                     throws java.io.IOException
Throws:
java.io.IOException
Method Detail

addFeatureListener

public void addFeatureListener(FeatureListener listener)
Description copied from interface: FeatureSource
Adds a listener to the list that's notified each time a change to the FeatureStore occurs.

Specified by:
addFeatureListener in interface FeatureSource
Parameters:
listener - FeatureListener

removeFeatureListener

public void removeFeatureListener(FeatureListener listener)
Description copied from interface: FeatureSource
Removes a listener from the list that's notified each time a change to the FeatureStore occurs.

Specified by:
removeFeatureListener in interface FeatureSource
Parameters:
listener - FeatureListener

getDataStore

public DataStore getDataStore()
Description copied from interface: FeatureSource
Access to the DataStore implementing this FeatureStore.

Specified by:
getDataStore in interface FeatureSource
Returns:
DataStore implementing this FeatureStore

getBounds

public ReferencedEnvelope getBounds()
                             throws java.io.IOException
Description copied from interface: FeatureSource
Gets the bounding box of this datasource.

With getBounds(Query) this becomes a convenience method for getBounds(Query.ALL), that is the bounds for all features contained here.

If getBounds() returns null due to expense consider using getFeatures().getBounds() as a an alternative.

Specified by:
getBounds in interface FeatureSource
Returns:
The bounding box of the datasource or null if unknown and too expensive for the method to calculate.
Throws:
java.io.IOException - if there are errors getting the bounding box.

getBounds

public ReferencedEnvelope getBounds(Query query)
                             throws java.io.IOException
Description copied from interface: FeatureSource
Gets the bounding box of the features that would be returned by this query.

To retrieve the bounds of the DataSource please use getBounds( Query.ALL ).

This method is needed if we are to stream features to a gml out, since a FeatureCollection must have a boundedBy element.

If getBounds(Query) returns null due to expense consider using getFeatures(Query).getBounds() as a an alternative.

Specified by:
getBounds in interface FeatureSource
Parameters:
query - Contains the Filter, and optionally MaxFeatures and StartIndex to find the bounds for.
Returns:
The bounding box of the datasource or null if unknown and too expensive for the method to calculate or any errors occur.
Throws:
java.io.IOException - DOCUMENT ME!

getCount

public int getCount(Query query)
             throws java.io.IOException
Description copied from interface: FeatureSource
Gets the number of the features that would be returned by this query.

If getBounds(Query) returns -1 due to expense consider using getFeatures(Query).getCount() as a an alternative.

This method should take into account the Query's maxFeatures and startIndex, if present, in order to consistently return the number of features the query would return.

Specified by:
getCount in interface FeatureSource
Parameters:
query - Contains the Filter, and optionally MaxFeatures and StartIndex to find the count for.
Returns:
The number of Features provided by the Query or -1 if count is too expensive to calculate or any errors or occur.
Throws:
java.io.IOException - if there are errors getting the count

getSchema

public org.opengis.feature.type.FeatureType getSchema()
Description copied from interface: FeatureSource
Retrieves the featureType that features extracted from this datasource will be created with.

The schema returned is the LCD supported by all available Features. In the common case of shapfiles and database table this schema will match that of every feature available. In the degenerate GML case this will simply reflect the gml:AbstractFeatureType.

Specified by:
getSchema in interface FeatureSource
Returns:
the schema of features created by this datasource.

getFeatures

public FeatureCollection getFeatures()
                              throws java.io.IOException
Description copied from interface: FeatureSource
Loads all features from the datasource into the return FeatureResults.

Filter.INCLUDE can also be used to get all features. Calling this function is equivalent to using Query.ALL

Specified by:
getFeatures in interface FeatureSource
Returns:
Collection The collection to put the features into.
Throws:
java.io.IOException - For all data source errors.

getFeatures

public FeatureCollection getFeatures(org.opengis.filter.Filter filter)
                              throws java.io.IOException
Description copied from interface: FeatureSource
Loads features from the datasource into the returned FeatureResults, based on the passed filter.

Specified by:
getFeatures in interface FeatureSource
Parameters:
filter - An OpenGIS filter; specifies which features to retrieve. null is not allowed, use Filter.INCLUDE instead.
Returns:
Collection The collection to put the features into.
Throws:
java.io.IOException - For all data source errors.

getFeatures

public FeatureCollection getFeatures(Query query)
                              throws java.io.IOException
Description copied from interface: FeatureSource
Loads features from the datasource into the returned FeatureResults, based on the passed query.

Specified by:
getFeatures in interface FeatureSource
Parameters:
query - a datasource query object. It encapsulates requested information, such as typeName, maxFeatures and filter.
Returns:
Collection The collection to put the features into.
Throws:
java.io.IOException - For all data source errors.
See Also:
Query

reType

public static org.opengis.feature.simple.SimpleFeature reType(org.opengis.feature.simple.SimpleFeatureType featureType,
                                                              org.opengis.feature.simple.SimpleFeature feature)
                                                       throws org.opengis.feature.IllegalAttributeException
Same as DataUtilities.reType, but without the cloning that uselessly wastes CPU cycles...

Parameters:
featureType -
feature -
Returns:
Throws:
org.opengis.feature.IllegalAttributeException

getInfo

public ResourceInfo getInfo()
Description copied from interface: FeatureSource
Information describing the contents of this resoruce.

Please note that for FeatureContent:


getName

public org.opengis.feature.type.Name getName()
Description copied from interface: FeatureSource
Returns the qualified name for the Features this FeatureSource serves.

Note this is different from getSchema().getType().getName() (that is, the feature type name), this name specifies the AttributeDescriptor name for the Features served by this source. So, FeatureSoruce.getName() == FeatureSource.getFeatures().next().getAttributeDescriptor().getName().

Though it's a common practice when dealing with SimpleFeatureType and SimpleFeature to assume they're equal. There's no conflict (as per the dynamic typing system the org.opengis.feature package defines) in a Feature and its type sharing the same name, as well as in a GML schema an element declaration and a type definition may be named the same. Yet, the distinction becomes important as we get rid of that assumption and thus allow to reuse a type definition for different FeatureSoruces, decoupling the descriptor (homologous to the Feature element declaration in a GML schema) from its type definition.

So, even if implementors are allowed to delegate to getSchema().getName() if they want to call the fatures and their type the same, client code asking a DataAccess.getFeatureSource(Name) shall use this name to request for a FeatureSource, rather than the type name, as used in pre 2.5 versions of GeoTools. For example, if we have a FeatureSource named Roads and its type is named Roads_Type, the DataAccess shall be queried through Roads, not Roads_Type.

Specified by:
getName in interface FeatureSource
Returns:
the name of the AttributeDescriptor for the Features served by this FeatureSource

getQueryCapabilities

public QueryCapabilities getQueryCapabilities()
Description copied from interface: FeatureSource
Returns and indication of what query capabilities this FeatureSource supports natively.

Specified by:
getQueryCapabilities in interface FeatureSource
Returns:
a QueryCapabilities object containing the native query capabilities.

getSupportedHints

public java.util.Set getSupportedHints()
Description copied from interface: FeatureSource
Returns the set of hints this FeatureSource is able to support.

Hints are to be specified in the Query, for each data access where they may be required.
Depending on the actual value provide by the user, the FeatureSource may decide not to honor the hint.

Specified by:
getSupportedHints in interface FeatureSource
Returns:
a set of RenderingHints#Key objects (eventually empty, never null).


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