org.apache.commons.compress.utils.ServiceLoaderIterator Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.commons.compress.utils;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.ServiceConfigurationError;
import java.util.ServiceLoader;
/**
* Iterates all services for a given class through the standard
* {@link ServiceLoader} mechanism.
*
* @param
* The service to load
* @since 1.13
*/
public class ServiceLoaderIterator implements Iterator {
private E nextServiceLoader;
private final Class service;
private final Iterator serviceLoaderIterator;
public ServiceLoaderIterator(final Class service) {
this(service, ClassLoader.getSystemClassLoader());
}
public ServiceLoaderIterator(final Class service, final ClassLoader classLoader) {
this.service = service;
final ServiceLoader serviceLoader = ServiceLoader.load(service, classLoader);
serviceLoaderIterator = serviceLoader.iterator();
nextServiceLoader = null;
}
private boolean getNextServiceLoader() {
while (nextServiceLoader == null) {
try {
if (!serviceLoaderIterator.hasNext()) {
return false;
}
nextServiceLoader = serviceLoaderIterator.next();
} catch (final ServiceConfigurationError e) {
if (e.getCause() instanceof SecurityException) {
// Ignore security exceptions
// TODO Log?
continue;
}
throw e;
}
}
return true;
}
@Override
public boolean hasNext() {
return getNextServiceLoader();
}
@Override
public E next() {
if (!getNextServiceLoader()) {
throw new NoSuchElementException("No more elements for service " + service.getName());
}
final E tempNext = nextServiceLoader;
nextServiceLoader = null;
return tempNext;
}
@Override
public void remove() {
throw new UnsupportedOperationException("service=" + service.getName());
}
}