org.springframework.cloud.gcp.storage.GoogleStorageProtocolResolver.java Source code

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Here is the source code for org.springframework.cloud.gcp.storage.GoogleStorageProtocolResolver.java

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/*
 * Copyright 2017-2018 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.cloud.gcp.storage;

import com.google.cloud.storage.Storage;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.context.ResourceLoaderAware;
import org.springframework.core.io.DefaultResourceLoader;
import org.springframework.core.io.ProtocolResolver;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;

/**
 * A {@link ProtocolResolver} implementation for the {@code gs://} protocol.
 *
 * @author Vinicius Carvalho
 * @author Artem Bilan
 * @author Mike Eltsufin
 * @author Chengyuan Zhao
 */
public class GoogleStorageProtocolResolver
        implements ProtocolResolver, BeanFactoryPostProcessor, ResourceLoaderAware {

    /**
     * The prefix of all storage locations.
     */
    public static final String PROTOCOL = "gs://";

    private static final Log logger = LogFactory.getLog(GoogleStorageProtocolResolver.class);

    private ConfigurableListableBeanFactory beanFactory;

    private Storage storage;

    private GoogleStorageProtocolResolverSettings googleStorageProtocolResolverSettings;

    GoogleStorageProtocolResolver() {
    }

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        this.beanFactory = beanFactory;
    }

    private Storage getStorage() {
        if (this.storage == null) {
            this.storage = this.beanFactory.getBean(Storage.class);
        }
        return this.storage;
    }

    private GoogleStorageProtocolResolverSettings getGoogleStorageProtocolResolverSettings() {
        if (this.googleStorageProtocolResolverSettings == null) {
            this.googleStorageProtocolResolverSettings = this.beanFactory
                    .getBean(GoogleStorageProtocolResolverSettings.class);
        }
        return this.googleStorageProtocolResolverSettings;
    }

    @Override
    public void setResourceLoader(ResourceLoader resourceLoader) {
        if (DefaultResourceLoader.class.isAssignableFrom(resourceLoader.getClass())) {
            ((DefaultResourceLoader) resourceLoader).addProtocolResolver(this);
        } else {
            logger.warn("The provided delegate resource loader is not an implementation "
                    + "of DefaultResourceLoader. Custom Protocol using gs:// prefix will not be enabled.");
        }
    }

    private GoogleStorageProtocolResolverSettings getSettings() {
        try {
            return getGoogleStorageProtocolResolverSettings();
        } catch (NoSuchBeanDefinitionException ex) {
            return GoogleStorageProtocolResolverSettings.DEFAULT_GOOGLE_STORAGE_PROTOCOL_RESOLVER_SETTINGS;
        }
    }

    @Override
    public Resource resolve(String location, ResourceLoader resourceLoader) {
        if (!location.startsWith(PROTOCOL)) {
            return null;
        }
        return new GoogleStorageResource(getStorage(), location, getSettings().isAutoCreateFiles());
    }
}