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package com.sun.appserv.ha.spi;
import java.util.Collection;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.ConcurrentHashMap;
/**
* A class for storing BackingStore implementation. This is a singleton and
* contains a mapping between persistence-type and
* <code>BackingStoreFactory</code>. An instance of this class can be
* obtained using <code>getInstance()</code> method.
*
* @see BackingStore
*/
public final class BackingStoreRegistry {
private static BackingStoreRegistry _instance = new BackingStoreRegistry();
private Map<String, BackingStoreInfo> type2BackingStoreInfo = new ConcurrentHashMap<String, BackingStoreInfo>();
// Private constructor
private BackingStoreRegistry() {
}
/**
* Return the (singleton) instance of BackingStoreRegistry
*
* @return BackingStoreRegistry
*/
public static BackingStoreRegistry getInstance() {
return _instance;
}
/**
* Register a BackingStoreFactory class name and any associated Properties
* for the given persistence type. The properties must contain any
* additional configuration paramters to properly initialize and use the
* store.
*
* @param type
* The persistence-type
* @param factoryClassName
* The factory class name for this type. This class must extend
* BackingStore.
* @param props
* Properties that contain additional configration paramters.
* @throws DuplicateFactoryRegistrationException
* If this type is already registered.
*
* @see BackingStoreFactory#createBackingStore(Class, String, Properties)
*/
public synchronized void register(String type, String factoryClassName, Properties props)
throws DuplicateFactoryRegistrationException {
if (type2BackingStoreInfo.get(type) != null) {
throw new DuplicateFactoryRegistrationException(
"Duplicate factory class (" + factoryClassName
+ ") for type: " + type);
} else {
type2BackingStoreInfo.put(type, new BackingStoreInfo(
factoryClassName, props));
}
}
/**
* Unregister the factory
*
* @param type
* the type
*/
public boolean remove(String type) {
return (type2BackingStoreInfo.remove(type) != null);
}
/**
* Get the registered factory for the type specified in the parameter
*
* @param type
* the type
* @return The BackingStoreFactory class name or null
*/
public String getFactoryClassName(String type) {
BackingStoreInfo info = type2BackingStoreInfo.get(type);
return (info == null) ? null : info.className;
}
/**
* Get the registered factory for the type specified in the parameter
*
* @param type
* the type
* @return The BackingStoreFactory env (Properties) or null
*/
public Properties getFactoryClassEnv(String type) {
BackingStoreInfo info = type2BackingStoreInfo.get(type);
return (info == null) ? null : info.props;
}
/**
* Return an instance of BackingStoreFactory for the specified type. If a
* factory instance for this persistence type has not yet been instantiated
* then an instance is created using the public no-arg constructor. Then
* {@link BackingStore#initialize(String, Properties)} will be called to
* properly initialize the BsackingStore.
*
* @param type
* the persistence type for which a factory is required
* @return an instance of BackingStoreFactory for the specified type
* @throws BackingStoreException
* if the store cannot be initialized properly.
* @throws ClassNotFoundException
* If the BackingStore class cannot be found.
* @throws InstantiationException
* If the BackingStore class cannot be instantiated.
* @throws IllegalAccessException
* If the BackingStore class doen't provide a public no-arg
* constructor
* @see BackingStore.initialize(String, Properties)
*/
public BackingStoreFactory getFactoryInstance(String type)
throws BackingStoreException, ClassNotFoundException,
InstantiationException, IllegalAccessException {
BackingStoreFactory factory = null;
BackingStoreInfo info = type2BackingStoreInfo.get(type);
if (info != null) {
if (info.factory == null) {
synchronized (info) {
Class clazz = Class.forName(info.className);
info.factory = (BackingStoreFactory) clazz.newInstance();
}
}
factory = info.factory;
}
return factory;
}
/**
* Get a list of all registered store type
*
* @return Collection<String> where each entry in the collection is the
* type
*/
public Collection<String> getRegisteredTypes() {
return type2BackingStoreInfo.keySet();
}
private static class BackingStoreInfo {
String className;
Properties props;
volatile BackingStoreFactory factory;
BackingStoreInfo(String className, Properties props) {
this.className = className;
this.props = props;
}
}
}
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