ServiceRegistry
FactoryRegistry
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Object
public class FactoryRegistry
A registry for factories, organized by categories (usualy by interface). For
example CRSFactory.class is a category,
and MathTransformFactory.class is
an other category.
For each category, implementations are registered in a file placed in the
META-INF/services/ directory, as specified in the ServiceRegistry
javadoc. Those files are usually bundled into the JAR file distributed by the vendor.
If the same META-INF/services/ file appears many time in different JARs,
they are processed as if their content were merged.
Example use:
Set<Class<?>> categories =
Collections.singleton(new Class<?>[] {
&npsp;&npsp;&npsp;&npsp;MathTransformProvider.class
});
FactoryRegistry registry = new FactoryRegistry(categories);
// get the providers
Filter filter = null;
Hints hints = null;
Iterator<MathTransform> providers =
registry.getServiceProviders(MathTransformProvider.class, filter, hints);
NOTE: This class is not thread safe. Users are responsable
for synchronisation. This is usually done in an utility class wrapping this
service registry (e.g. ReferencingFactoryFinder).
ReferencingFactoryFinder,
CoverageFactoryFinder| Nested Class Summary |
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| Nested classes/interfaces inherited from class ServiceRegistry |
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ServiceRegistry.Filter |
| Field Summary | |
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protected static Logger |
LOGGER
The logger for all events related to factory registry. |
| Constructor Summary | |
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FactoryRegistry(Class<?> category)
Constructs a new registry for the specified category. |
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FactoryRegistry(Class<?>[] categories)
Constructs a new registry for the specified categories. |
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FactoryRegistry(Collection<Class<?>> categories)
Constructs a new registry for the specified categories. |
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| Method Summary | ||
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Set<ClassLoader> |
getClassLoaders()
Returns all class loaders to be used for scanning plugins. |
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getServiceProvider(Class<T> category,
ServiceRegistry.Filter filter,
Hints hints,
Hints.Key key)
Returns the first provider in the registry for the specified category, using the specified map of hints (if any). |
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getServiceProviders(Class<T> category,
ServiceRegistry.Filter filter,
Hints hints)
Returns the providers in the registry for the specified category, filter and hints. |
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protected
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isAcceptable(T provider,
Class<T> category,
Hints hints)
Returns true if the specified provider meets the requirements specified by
a map of hints. |
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void |
scanForPlugins()
Scans for factory plug-ins on the application class path. |
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setOrdering(Class<T> base,
boolean set,
ServiceRegistry.Filter service1,
ServiceRegistry.Filter service2)
Sets or unsets a pairwise ordering between all factories meeting a criterion. |
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setOrdering(Class<T> category,
Comparator<T> comparator)
Set pairwise ordering between all factories according a comparator. |
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| Methods inherited from class Object |
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clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Field Detail |
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protected static final Logger LOGGER
| Constructor Detail |
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public FactoryRegistry(Class<?> category)
category - The single category.public FactoryRegistry(Class<?>[] categories)
categories - The categories.public FactoryRegistry(Collection<Class<?>> categories)
categories - The categories.| Method Detail |
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public <T> Iterator<T> getServiceProviders(Class<T> category,
ServiceRegistry.Filter filter,
Hints hints)
T - The class represented by the category argument.category - The category to look for. Usually an interface class
(not the actual implementation class).filter - The optional filter, or null.hints - The optional user requirements, or null.
public <T> T getServiceProvider(Class<T> category,
ServiceRegistry.Filter filter,
Hints hints,
Hints.Key key)
throws FactoryRegistryException
FactoryCreator class
change this behavior however.
T - The class represented by the category argument.category - The category to look for. Must be one of the categories declared to the
constructor. Usually an interface class (not the actual implementation
class).filter - An optional filter, or null if none.
This is used for example in order to select the first factory for some
authority.hints - A map of hints, or null if none.key - The key to use for looking for a user-provided instance in the hints, or
null if none.
Object instead of
Factory because the factory implementation doesn't need to be a Geotools one.
FactoryNotFoundException - if no factory was found for the specified category, filter
and hints.
FactoryRegistryException - if a factory can't be returned for some other reason.#getServiceProviders(Class, Filter, Hints),
FactoryCreator.getServiceProvider(java.lang.Class, javax.imageio.spi.ServiceRegistry.Filter, org.geotools.factory.Hints, org.geotools.factory.Hints.Key)
protected <T> boolean isAcceptable(T provider,
Class<T> category,
Hints hints)
true if the specified provider meets the requirements specified by
a map of hints. The default implementation always returns true. There is no
need to override this method for AbstractFactory implementations, since their hints
are automatically checked. Override this method for non-Geotools implementations.
For example a JTS geometry factory finder may overrides this method in order to check
if a GeometryFactory uses the required
CoordinateSequenceFactory. Such method should be
implemented as below, since this method may be invoked for various kind of objects:
if (provider instanceof GeometryFactory) {
// ... Check the GeometryFactory state here.
}
T - The class represented by the category argument.provider - The provider to checks.category - The factory category. Usually an interface.hints - The user requirements, or null if none.
true if the provider meets the user requirements.public final Set<ClassLoader> getClassLoaders()
The actual number of class loaders may be smaller if redundancies was found. If some more classloaders should be scanned, they shall be added into the code of this method.
public void scanForPlugins()
public <T> boolean setOrdering(Class<T> category,
Comparator<T> comparator)
compare(factory1, factory2) should returns:
-1 if factory1 is preferred to factory2+1 if factory2 is preferred to factory10 if there is no preferred order between factory1 and
factory2
T - The class represented by the category argument.category - The category to set ordering.comparator - The comparator to use for ordering.
true if at least one ordering setting has been modified as a consequence
of this call.
public <T> boolean setOrdering(Class<T> base,
boolean set,
ServiceRegistry.Filter service1,
ServiceRegistry.Filter service2)
org.geotools.referencing.FactoryFinder), this is used for
setting ordering between all factories provided by two vendors, or for two authorities.
If one or both factories are not currently registered, or if the desired ordering is
already set/unset, nothing happens and false is returned.
T - The class represented by the base argument.base - The base category. Only categories assignable to base will be processed.set - true for setting the ordering, or false for unsetting.service1 - Filter for the preferred factory.service2 - Filter for the factory to which service1 is preferred.
true if the ordering changed as a result of this call.
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