Package org.geotools.util.factory
Because Geotools core API consists almost exclusively of interfaces, factories play a role in how developers use the API. Although the interfaces are implemented in various GeoTools packages you should not use those classes directly. Instead you should use factories.
GeoTools FactoryRegistry
provides a general to instantiate and
manage factories (also called service providers). Each factory implementation is found
using ServiceLocator (declaired in module-info.java
or in
jar META-INF/services
directory.
org.opengis.referencing.datum.DatumFactory
implementations, then it must provide the following file:
META-INF/services/org.opengis.referencing.datum.DatumFactory
with a content similar to the one below:
com.mycompany.MyDatumFactory1 com.mycompany.MyDatumFactory2 com.mycompany.MyDatumFactory3
The ordering is initially unspecified. Users can
set an ordering
explicitly themselves, or implementations can do that automatically
on registration.
The org.geotools.factory.AbstractFactory
class provides a simple way to setup ordering
on registration on the basis of a priority
number.
If a user wants a specific implementation, he can
iterates through registered ones
and pickup the desired implementation himself. An alternative is to bundle the criterions in a
map of hints and lets the registry selects an implementation
accordingly. This later functionality is not provided by the standard ServiceRegistry
,
but is provided by Geotools's org.geotools.factory.FactoryRegistry
extension. This class extends
the service registry API with the following functionalities:
A
scanForPlugins()
method that scans for plugins in the registry class loader, the thread context class loader and the system class loader. Additionally,scanForPlugins()
looks for any implementation specified as system property.Filters out automatically optional factories when they are not available.
When more than one implementation is available for the same
org.geotools.factory.Factory
subinterface, an optional set of hints can specifies the criterions that the desired implementation must meets. If a factory implementation depends on other factories, the dependencies hints are checked recursively.Optionally, if no factory matches the given hints, a new instance can be automatically created.
Note that the hints, if provided, don't need to apply
directly to the requested factory category. They may apply indirectly through some dependency. A typical example is
a request for any GeometryFactory
instance, providing that this instance uses a
particular CoordinateSequenceFactory
implementation.
-
Interface Summary Interface Description BufferedFactory A marker interface for factories that are buffering their objects in some way.Factory Base interface for Geotools factories (i.e. service discovery).FactoryIteratorProvider Provides iterators over factories of specified categories.OptionalFactory An optional factory that may not be available in all configurations.RegistrableFactory -
Class Summary Class Description AbstractFactory Skeletal implementation of factories.FactoryCreator A factory registry capable to creates factories if no appropriate instance was found in the registry.FactoryFinder Base class for factory finders.FactoryRegistry A registry for factories, organized by categories (usually by interface).GeoTools Static methods relative to the global GeoTools configuration.Hints A set of hints providing control on factories to be used.Hints.ClassKey A key for value that may be specified either as instance ofT
, or asClass<T>
.Hints.ConfigurationMetadataKey Keys for extra configuration options that are passed from the overhead application into queries.Hints.DoubleKey A hint used to capture a configuration setting as double.Hints.FileKey Key for hints to be specified as aFile
.Hints.IntegerKey A hint used to capture a configuration setting as an integer.Hints.Key The type for keys used to control various aspects of the factory creation.Hints.OptionKey Key that allows the choice of several options. -
Exception Summary Exception Description FactoryNotFoundException Thrown when a factory can't be found in the registery.FactoryRegistryException Thrown when a factory can't be found or can't be instantiate.RecursiveSearchException Thrown whenFactoryRegistry
is invoked recursively for the same category.