/*
 * Copyright 2012-2020 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 org.apache.commons.logging.Log;

import org.springframework.boot.BootstrapContext;
import org.springframework.boot.BootstrapRegistry;
import org.springframework.boot.ConfigurableBootstrapContext;

Strategy class that can be used used to load ConfigData for a given ConfigDataResource. Implementations should be added as a spring.factories entries. The following constructor parameter types are supported: 

Log - if the resolver needs deferred logging
ConfigurableBootstrapContext - A bootstrap context that can be used to store objects that may be expensive to create, or need to be shared (BootstrapContext or BootstrapRegistry may also be used).


Multiple loaders cannot claim the same resource.
Author:
Phillip Webb, Madhura Bhave
Type parameters:
<R> – the resource type
Since:
2.4.0/**
 * Strategy class that can be used used to load {@link ConfigData} for a given
 * {@link ConfigDataResource}. Implementations should be added as a
 * {@code spring.factories} entries. The following constructor parameter types are
 * supported:
 * <ul>
 * <li>{@link Log} - if the resolver needs deferred logging</li>
 * <li>{@link ConfigurableBootstrapContext} - A bootstrap context that can be used to
 * store objects that may be expensive to create, or need to be shared
 * ({@link BootstrapContext} or {@link BootstrapRegistry} may also be used).</li>
 * </ul>
 * <p>
 * Multiple loaders cannot claim the same resource.
 *
 * @param <R> the resource type
 * @author Phillip Webb
 * @author Madhura Bhave
 * @since 2.4.0
 */
public interface ConfigDataLoader<R extends ConfigDataResource> {

	
Returns if the specified resource can be loaded by this instance.
Params:
context – the loader context
resource – the resource to check.
Returns:
if the resource is supported by this loader/**
	 * Returns if the specified resource can be loaded by this instance.
	 * @param context the loader context
	 * @param resource the resource to check.
	 * @return if the resource is supported by this loader
	 */
	default boolean isLoadable(ConfigDataLoaderContext context, R resource) {
		return true;
	}

	
Load ConfigData for the given resource. 
Params:
context – the loader context
resource – the resource to load
Throws:
IOException – on IO error
ConfigDataResourceNotFoundException – if the resource cannot be found
Returns:
the loaded config data or null if the location should be skipped/**
	 * Load {@link ConfigData} for the given resource.
	 * @param context the loader context
	 * @param resource the resource to load
	 * @return the loaded config data or {@code null} if the location should be skipped
	 * @throws IOException on IO error
	 * @throws ConfigDataResourceNotFoundException if the resource cannot be found
	 */
	ConfigData load(ConfigDataLoaderContext context, R resource)
			throws IOException, ConfigDataResourceNotFoundException;

}