com.github.triceo.robozonky.common.extensions.ExtensionsManager Maven / Gradle / Ivy
/*
* Copyright 2017 The RoboZonky Project
*
* Licensed 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 com.github.triceo.robozonky.common.extensions;
import java.io.File;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Collection;
import java.util.ServiceLoader;
import com.github.triceo.robozonky.util.FileUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Ensures that all extensions, available in the current working directory's "extensions/" subdirectory, will be on
* the classpath.
*
* All extension points implementing {@link ServiceLoader} must call this class to retrieve the instance.
*/
enum ExtensionsManager {
INSTANCE; // cheap thread-safe singleton
ClassLoader retrieveExtensionClassLoader(final File extensionsFolder) {
this.LOGGER.debug("Using extensions folder: '{}'.", extensionsFolder.getAbsolutePath());
final Collection urls =
FileUtils.filesToUrls(extensionsFolder.listFiles(f -> f.getPath().toLowerCase().endsWith(".jar")));
return new URLClassLoader(urls.toArray(new URL[urls.size()]));
}
ClassLoader retrieveExtensionClassLoader(final String folderName) {
return FileUtils.findFolder(folderName)
.map(this::retrieveExtensionClassLoader)
.orElseGet(() -> {
this.LOGGER.debug("Extensions folder not found.");
return ExtensionsManager.class.getClassLoader();
});
}
private final Logger LOGGER = LoggerFactory.getLogger(ExtensionsManager.class);
public ServiceLoader getServiceLoader(final Class serviceClass) {
return getServiceLoader(serviceClass, "extensions");
}
ServiceLoader getServiceLoader(final Class serviceClass, final String folderName) {
this.LOGGER.debug("Retrieving service loader for '{}'.", serviceClass);
return ServiceLoader.load(serviceClass, this.retrieveExtensionClassLoader(folderName));
}
}