Package liquibase.plugin

Class AbstractPluginFactory<T extends Plugin>

java.lang.Object

liquibase.plugin.AbstractPluginFactory<T>

All Implemented Interfaces:

PluginFactory, SingletonObject

Direct Known Subclasses:

ChangeFactory, ChangeLogHistoryServiceFactory, ChangeSetServiceFactory, ExecutorService, LicenseServiceFactory, LogFactory, LogServiceFactory, MdcManagerFactory, PathHandlerFactory, ShowSummaryGeneratorFactory, SqlParserFactory, TestSystemFactory, UIServiceFactory

public abstract class AbstractPluginFactory<T extends Plugin>
extends Object
implements PluginFactory

Convenience base class for all factories that find correct Plugin implementations.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractPluginFactory()

Method Summary

Modifier and Type	Method	Description
protected Collection<T>	findAllInstances()	Finds implementations of the given interface or class and returns instances of them.
protected T	getPlugin(Object... args)	Finds the plugin for which getPriority(Plugin, Object...) returns the highest value for the given scope and args.
protected abstract Class<T>	getPluginClass()
protected Set<T>	getPlugins(Object... args)
protected abstract int	getPriority(T obj, Object... args)	Returns the priority of the given object based on the passed args array.
void	register(T plugin)
protected void	removeInstance(T instance)

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractPluginFactory

protected AbstractPluginFactory()

Method Detail

getPluginClass

protected abstract Class<T> getPluginClass()

getPriority

protected abstract int getPriority(T obj,
                                   Object... args)

Returns the priority of the given object based on the passed args array. The args are created as part of the custom public getPlugin method in implementations are passed through getPlugin(Object...)

getPlugin

protected T getPlugin(Object... args)

Finds the plugin for which getPriority(Plugin, Object...) returns the highest value for the given scope and args. This method is called by a public implementation-specific methods. Normally this does not need to be overridden, instead override getPriority(Plugin, Object...) to compute the priority of each object for the scope and arguments passed to this method.

However, if there is a Scope key of "liquibase.plugin.${plugin.interface.class.Name}", an instance of that class will always be ran first.

Returns:

null if no plugins are found or have a priority greater than zero.

getPlugins

protected Set<T> getPlugins(Object... args)

register

public void register(T plugin)

findAllInstances

protected Collection<T> findAllInstances()

Finds implementations of the given interface or class and returns instances of them. Standard implementation uses ServiceLoader to find implementations and caches results in allInstances which means the same objects are always returned. If the instances should not be treated as singletons, clone the objects before returning them from getPlugin(Object...).

removeInstance

protected void removeInstance(T instance)