org.springframework.boot.context.config.ConfigDataLoaders Maven / Gradle / Ivy
/*
* Copyright 2012-2021 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.boot.context.config;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.apache.commons.logging.Log;
import org.springframework.boot.BootstrapContext;
import org.springframework.boot.BootstrapRegistry;
import org.springframework.boot.ConfigurableBootstrapContext;
import org.springframework.boot.logging.DeferredLogFactory;
import org.springframework.boot.util.Instantiator;
import org.springframework.core.ResolvableType;
import org.springframework.core.io.support.SpringFactoriesLoader;
import org.springframework.core.log.LogMessage;
import org.springframework.util.Assert;
/**
* A collection of {@link ConfigDataLoader} instances loaded via {@code spring.factories}.
*
* @author Phillip Webb
* @author Madhura Bhave
*/
class ConfigDataLoaders {
private final Log logger;
private final List> loaders;
private final List> resourceTypes;
/**
* Create a new {@link ConfigDataLoaders} instance.
* @param logFactory the deferred log factory
* @param bootstrapContext the bootstrap context
*/
ConfigDataLoaders(DeferredLogFactory logFactory, ConfigurableBootstrapContext bootstrapContext) {
this(logFactory, bootstrapContext, SpringFactoriesLoader.loadFactoryNames(ConfigDataLoader.class, null));
}
/**
* Create a new {@link ConfigDataLoaders} instance.
* @param logFactory the deferred log factory
* @param bootstrapContext the bootstrap context
* @param names the {@link ConfigDataLoader} class names instantiate
*/
ConfigDataLoaders(DeferredLogFactory logFactory, ConfigurableBootstrapContext bootstrapContext,
List names) {
this.logger = logFactory.getLog(getClass());
Instantiator> instantiator = new Instantiator<>(ConfigDataLoader.class,
(availableParameters) -> {
availableParameters.add(Log.class, logFactory::getLog);
availableParameters.add(DeferredLogFactory.class, logFactory);
availableParameters.add(ConfigurableBootstrapContext.class, bootstrapContext);
availableParameters.add(BootstrapContext.class, bootstrapContext);
availableParameters.add(BootstrapRegistry.class, bootstrapContext);
});
this.loaders = instantiator.instantiate(names);
this.resourceTypes = getResourceTypes(this.loaders);
}
private List> getResourceTypes(List> loaders) {
List> resourceTypes = new ArrayList<>(loaders.size());
for (ConfigDataLoader loader : loaders) {
resourceTypes.add(getResourceType(loader));
}
return Collections.unmodifiableList(resourceTypes);
}
private Class getResourceType(ConfigDataLoader loader) {
return ResolvableType.forClass(loader.getClass()).as(ConfigDataLoader.class).resolveGeneric();
}
/**
* Load {@link ConfigData} using the first appropriate {@link ConfigDataLoader}.
* @param the resource type
* @param context the loader context
* @param resource the resource to load
* @return the loaded {@link ConfigData}
* @throws IOException on IO error
*/
ConfigData load(ConfigDataLoaderContext context, R resource) throws IOException {
ConfigDataLoader loader = getLoader(context, resource);
this.logger.trace(LogMessage.of(() -> "Loading " + resource + " using loader " + loader.getClass().getName()));
return loader.load(context, resource);
}
@SuppressWarnings("unchecked")
private ConfigDataLoader getLoader(ConfigDataLoaderContext context, R resource) {
ConfigDataLoader result = null;
for (int i = 0; i < this.loaders.size(); i++) {
ConfigDataLoader candidate = this.loaders.get(i);
if (this.resourceTypes.get(i).isInstance(resource)) {
ConfigDataLoader loader = (ConfigDataLoader) candidate;
if (loader.isLoadable(context, resource)) {
if (result != null) {
throw new IllegalStateException("Multiple loaders found for resource '" + resource + "' ["
+ candidate.getClass().getName() + "," + result.getClass().getName() + "]");
}
result = loader;
}
}
}
Assert.state(result != null, () -> "No loader found for resource '" + resource + "'");
return result;
}
}