io.helidon.config.ClasspathConfigSource Maven / Gradle / Ivy
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/*
* Copyright (c) 2017, 2020 Oracle and/or its affiliates.
*
* 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 io.helidon.config;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.Collection;
import java.util.Enumeration;
import java.util.LinkedList;
import java.util.List;
import java.util.Optional;
import io.helidon.common.LazyValue;
import io.helidon.common.media.type.MediaTypes;
import io.helidon.config.spi.ConfigParser;
import io.helidon.config.spi.ConfigParser.Content;
import io.helidon.config.spi.ConfigSource;
import io.helidon.config.spi.ParsableSource;
/**
* {@link ConfigSource} implementation that loads configuration content from a resource on a classpath.
* Classpath config source does not support changes (neither through polling nor through change notifications).
*/
public class ClasspathConfigSource extends AbstractConfigSource implements ConfigSource,
ParsableSource {
private final String resource;
private final URL resourceUrl;
private final LazyValue> mediaType;
ClasspathConfigSource(Builder builder) {
super(builder);
this.resource = builder.resource;
this.resourceUrl = builder.url;
mediaType = LazyValue.create(() -> {
if (null == resourceUrl) {
return MediaTypes.detectType(resource);
} else {
return MediaTypes.detectType(resource);
}
});
}
/**
* Initializes config source instance from configuration properties.
*
* Mandatory {@code properties}, see {@link io.helidon.config.ConfigSources#classpath(String)}:
*
* - {@code resource} - type {@code String}
*
* Optional {@code properties}: see {@link AbstractConfigSourceBuilder#config(io.helidon.config.Config)}.
*
* @param metaConfig meta-configuration used to initialize returned config source instance from.
* @return new instance of config source described by {@code metaConfig}
* @throws MissingValueException in case the configuration tree does not contain all expected sub-nodes
* required by the mapper implementation to provide instance of Java type.
* @throws ConfigMappingException in case the mapper fails to map the (existing) configuration tree represented by the
* supplied configuration node to an instance of a given Java type.
* @see io.helidon.config.ConfigSources#classpath(String)
* @see AbstractConfigSourceBuilder#config(Config)
*/
public static ClasspathConfigSource create(Config metaConfig) throws ConfigMappingException, MissingValueException {
return builder()
.config(metaConfig)
.build();
}
/**
* Create a config source for the first resource on the classpath.
*
* @param resource resource to find
* @return a config source based on the classpath resource
*/
public static ClasspathConfigSource create(String resource) {
return builder().resource(resource).build();
}
/**
* Create config source for each resource on the classpath.
*
* @param resource resource to find
* @return a collection of sources for each resource present on the classpath, always at least one
*/
public static Collection createAll(String resource) {
Enumeration resources = findAllResources(resource);
if (resources.hasMoreElements()) {
List sources = new LinkedList<>();
while (resources.hasMoreElements()) {
URL url = resources.nextElement();
sources.add(builder().url(url).build());
}
return sources;
} else {
// there is none - let the default source handle it, to manage optional vs. mandatory
// with configuration and not an empty list
return List.of(create(resource));
}
}
/**
* Create config source for each resource on the classpath.
*
* @param metaConfig meta configuration of the config source
* @return a collection of sources for each resource present on the classpath
*/
public static List createAll(Config metaConfig) {
// this must fail if the resource is not defined
String resource = metaConfig.get("resource").asString().get();
Enumeration resources = findAllResources(resource);
if (resources.hasMoreElements()) {
List sources = new LinkedList<>();
while (resources.hasMoreElements()) {
URL url = resources.nextElement();
sources.add(builder()
.config(metaConfig)
// url must be configured after meta config, to override the default
.url(url)
.build());
}
return sources;
} else {
// there is none - let the default source handle it, to manage optional vs. mandatory
// with configuration and not an empty list
return List.of(create(metaConfig));
}
}
/**
* Create a new fluent API builder for classpath config source.
*
* @return a new builder instance
*/
public static Builder builder() {
return new Builder();
}
@Override
protected String uid() {
return (null == resourceUrl) ? resource : resourceUrl.toString();
}
@Override
public Optional load() throws ConfigException {
if (null == resourceUrl) {
return Optional.empty();
}
InputStream inputStream;
try {
inputStream = resourceUrl.openStream();
} catch (IOException e) {
throw new ConfigException("Failed to read configuration from classpath, resource: " + resource, e);
}
Content.Builder builder = Content.builder()
.data(inputStream);
mediaType.get().ifPresent(builder::mediaType);
return Optional.of(builder.build());
}
@Override
public String toString() {
return "classpath: " + resource;
}
@Override
public Optional mediaType() {
return super.mediaType();
}
@Override
public Optional parser() {
return super.parser();
}
private static Enumeration findAllResources(String resource) {
String cleaned = resource.startsWith("/") ? resource.substring(1) : resource;
try {
return Thread.currentThread()
.getContextClassLoader()
.getResources(cleaned);
} catch (IOException e) {
throw new ConfigException("Could not access config resource " + resource, e);
}
}
/**
* Classpath ConfigSource Builder.
*
* It allows to configure following properties:
*
* - {@code resource} - configuration resource name;
* - {@code optional} - is existence of configuration resource mandatory (by default) or is {@code optional}?
* - {@code media-type} - configuration content media type to be used to look for appropriate {@link ConfigParser};
* - {@code parser} - or directly set {@link ConfigParser} instance to be used to parse the source;
*
*
* If the ConfigSource is {@code mandatory} and a {@code resource} does not exist
* then {@link io.helidon.config.spi.ParsableSource#load} throws {@link ConfigException}.
*
* If {@code media-type} not set it tries to guess it from resource extension.
*/
public static final class Builder extends AbstractConfigSourceBuilder
implements ParsableSource.Builder,
io.helidon.common.Builder {
private URL url;
private String resource;
/**
* Initialize builder.
*/
private Builder() {
}
/**
* Builds new instance of Classpath ConfigSource.
*
* If {@code media-type} not set it tries to guess it from resource extension before parsing.
*
* @return new instance of Classpath ConfigSource.
*/
@Override
public ClasspathConfigSource build() {
return new ClasspathConfigSource(this);
}
/**
* {@inheritDoc}
*
* - {@code resource} - the classpath resource to load
*
* @param metaConfig configuration properties used to configure a builder instance.
* @return updated builder instance
*/
@Override
public Builder config(Config metaConfig) {
metaConfig.get("resource").asString().ifPresent(this::resource);
return super.config(metaConfig);
}
@Override
public Builder parser(ConfigParser parser) {
return super.parser(parser);
}
@Override
public Builder mediaType(String mediaType) {
return super.mediaType(mediaType);
}
/**
* Configure the classpath resource to load the configuration from.
*
* @param resource resource on classpath
* @return updated builder instance
*/
public Builder resource(String resource) {
String cleaned = resource.startsWith("/") ? resource.substring(1) : resource;
this.resource = resource;
// the URL may not exist, and that is fine - maybe we are an optional config source
this.url = Thread.currentThread()
.getContextClassLoader()
.getResource(cleaned);
return this;
}
private Builder url(URL url) {
this.url = url;
return this;
}
}
}