se.idsec.signservice.integration.core.ContentLoaderSingleton Maven / Gradle / Ivy
/*
* Copyright 2019-2022 IDsec Solutions AB
*
* 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 se.idsec.signservice.integration.core;
import java.io.IOException;
/**
* A singleton to be used internally for loading resources. By default the {@link DefaultContentLoader} is used. This
* can be overridden by installing a customized content loader using {@link #setContentLoader(ContentLoader)}.
*
* @author Martin Lindström ([email protected])
* @author Stefan Santesson ([email protected])
*/
public class ContentLoaderSingleton implements ContentLoader {
/** The content loader used. */
private ContentLoader contentLoader;
/** The singleton instance. */
private final static ContentLoaderSingleton INSTANCE = new ContentLoaderSingleton();
/**
* Gets the singleton instance of the global content loader.
*
* @return a ContentLoader
*/
public static ContentLoader getInstance() {
return INSTANCE;
}
/** {@inheritDoc} */
@Override
public byte[] loadContent(final String resource) throws IOException {
return this.getContentLoader().loadContent(resource);
}
/**
* If the global {@link ContentLoader} should be something else than {@link DefaultContentLoader} this method should
* be used to assign this.
*
* @param loader the content loader to set
*/
public void setContentLoader(final ContentLoader loader) {
if (this.contentLoader != null) {
throw new IllegalArgumentException("Global ContentLoader has already been configured");
}
if (loader != null) {
this.contentLoader = loader;
}
}
/**
* Gets the {@link ContentLoader} to use. If a specific content loader has not been assigned (using
* {@link #setContentLoader(ContentLoader)}) an {@link DefaultContentLoader} instance will be used.
*
* @return the content loader to use
*/
private ContentLoader getContentLoader() {
if (this.contentLoader == null) {
this.contentLoader = new DefaultContentLoader();
}
return this.contentLoader;
}
// Hidden constructor
private ContentLoaderSingleton() {
}
}