@SuppressWarnings("unchecked")
private static <T> List<T> loadServices(Class<T> clazz) {
final Map<T, Double> services = new IdentityHashMap<T, Double>();
Enumeration<URL> resourceList;
try {
resourceList =
clazz
.getClassLoader()
.getResources("META-INF/services/" + clazz.getName() + ".properties");
} catch (IOException e) {
throw new RegisteredExceptionWrapper("Could not load resources for " + clazz, e);
}
while (resourceList.hasMoreElements()) {
URL resource = resourceList.nextElement();
Properties properties = new Properties();
try {
properties.load(resource.openStream());
} catch (IOException e) {
LOG.log(Level.WARNING, "Could not load service list for " + clazz + " from " + resource, e);
}
for (Entry<Object, Object> e : properties.entrySet()) {
T service;
try {
service = (T) Class.forName(e.getKey().toString()).newInstance();
} catch (Exception ex) {
LOG.log(
Level.WARNING,
"Service "
+ e.getKey()
+ " defined in "
+ resource
+ " could not be loaded and was skipped",
ex);
continue;
}
Double priority;
try {
priority = Double.valueOf(e.getValue().toString());
} catch (NumberFormatException ex) {
LOG.warning(
"Service "
+ e.getKey()
+ " defined in "
+ resource
+ " has invalid priority "
+ e.getValue()
+ ": "
+ ex.getMessage()
+ " Default priority used");
priority = 0.0;
}
services.put(service, priority);
}
}
List<T> rc = new ArrayList<T>(services.keySet());
Collections.sort(
rc,
new Comparator<T>() {
public int compare(T o1, T o2) {
return services.get(o2).compareTo(services.get(o1));
}
});
return Collections.unmodifiableList(rc);
}
