/**
* If a system property was setup, load the class (if not already registered) and move it in front
* of any other factory. This is done for compatibility with legacy {@code FactoryFinder}
* implementation.
*
* @param loader The class loader to use.
* @param category The category to scan for plug-ins.
* @param message A buffer where to write the logging message.
* @return {@code true} if at least one factory has been registered.
*/
private <T> boolean registerFromSystemProperty(
final ClassLoader loader, final Class<T> category, final StringBuilder message) {
boolean newServices = false;
try {
final String classname = System.getProperty(category.getName());
if (classname != null)
try {
final Class<?> candidate = loader.loadClass(classname);
if (category.isAssignableFrom(candidate)) {
final Class<? extends T> factoryClass = candidate.asSubclass(category);
T factory = getServiceProviderByClass(factoryClass);
if (factory == null)
try {
factory = factoryClass.newInstance();
if (registerServiceProvider(factory, category)) {
message.append(System.getProperty("line.separator", "\n"));
message.append(" ");
message.append(factoryClass.getName());
newServices = true;
}
} catch (IllegalAccessException exception) {
throw new FactoryRegistryException(
Errors.format(ErrorKeys.CANT_CREATE_FACTORY_$1, classname), exception);
} catch (InstantiationException exception) {
throw new FactoryRegistryException(
Errors.format(ErrorKeys.CANT_CREATE_FACTORY_$1, classname), exception);
}
/*
* Put this factory in front of every other factories (including the ones loaded
* in previous class loaders, which is why we don't inline this ordering in the
* 'register' loop). Note: if some factories were not yet registered, they will
* not be properly ordered. Since this code exists more for compatibility reasons
* than as a commited API, we ignore this short comming for now.
*/
for (final Iterator<T> it = getServiceProviders(category, false); it.hasNext(); ) {
final T other = it.next();
if (other != factory) {
setOrdering(category, factory, other);
}
}
}
} catch (ClassNotFoundException exception) {
// The class has not been found, maybe because we are not using the appropriate
// class loader. Ignore (do not thrown an exception), in order to give a chance
// to the caller to invokes this method again with a different class loader.
}
} catch (SecurityException exception) {
// We are not allowed to read property, probably
// because we are running in an applet. Ignore...
}
return newServices;
}
