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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.tamaya.metamodel;
import org.apache.tamaya.base.ServiceContext;
import org.apache.tamaya.metamodel.spi.MetaConfigReader;
import org.apache.tamaya.base.ServiceContextManager;
import org.w3c.dom.Document;
import org.xml.sax.SAXException;
import javax.config.Config;
import javax.config.spi.ConfigBuilder;
import javax.config.spi.ConfigProviderResolver;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Objects;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Accessor singleton for accessing/loading meta-configuration.
*/
public final class MetaConfig {
private static final String CONFIG_RESOURCE = "tamaya-config.xml";
private static final Logger LOG = Logger.getLogger(MetaConfig.class.getName());
/**
* Singleton constructor.
*/
private MetaConfig(){}
/**
* Creates a new {@link Config} using {@link #createConfig(URL)}
* and applies it as default configuration using {@link ConfigProviderResolver#registerConfig(Config, ClassLoader)} .
*/
public static void configure(ClassLoader classLoader){
LOG.info("TAMAYA: Checking for meta-configuration...");
URL configFile = getDefaultMetaConfig();
if(configFile==null){
LOG.warning("TAMAYA: No " + CONFIG_RESOURCE + " found, using defaults.");
}
configure(configFile, classLoader);
}
/**
* Creates a new {@link Config} using {@link #createConfig(URL)}
* and applies it as default configuration using {@link ConfigProviderResolver#registerConfig(Config, ClassLoader)} .
* @param metaConfig URL for loading the {@code tamaya-config.xml} meta-configuration.
*/
public static void configure(URL metaConfig, ClassLoader classloader){
try {
// Let readers do their work
Config config = createConfig(metaConfig);
ConfigProviderResolver.instance().registerConfig(config, classloader);
}catch(Exception e){
LOG.log(Level.SEVERE, "TAMAYA: Error loading configuration.", e);
}
}
private static URL getDefaultMetaConfig() {
// 1: check tamaya-config system property
String tamayaConfig = System.getProperty("tamaya-config");
if(tamayaConfig!=null){
File file = new File(tamayaConfig);
if(!file.exists() || !file.canRead() || !file.isFile()){
LOG.severe("TAMAYA: Not a valid config file: " + tamayaConfig);
}else{
try {
return file.toURI().toURL();
} catch (MalformedURLException e) {
LOG.severe("TAMAYA: Invalid file name: " + tamayaConfig);
}
}
}
return MetaConfig.class.getClassLoader().getResource(CONFIG_RESOURCE);
}
/**
* Performs initialization of a new configuration
* context to the {@link MetaConfigReader} instances found in the current
* {@link ServiceContext} and returns the corresponding builder
* instance.
* @param metaConfig URL for loading the {@code tamaya-config.xml} meta-configuration.
* @return a new configuration context builder, never null.
* @throws IllegalStateException If the URL cannot be read.
*/
public static ConfigBuilder createConfigBuilder(URL metaConfig){
URL configFile = Objects.requireNonNull(metaConfig);
LOG.info("TAMAYA: Loading tamaya-config.xml...");
Document document = null;
try {
document = DocumentBuilderFactory.newInstance()
.newDocumentBuilder().parse(configFile.openStream());
ConfigBuilder builder = ConfigProviderResolver.instance().getBuilder();
for(MetaConfigReader reader: ServiceContextManager.getServiceContext().getServices(
MetaConfigReader.class
)){
LOG.fine("TAMAYA: Executing MetaConfig-Reader: " + reader.getClass().getName() + "...");
reader.read(document, builder);
}
return builder;
} catch (SAXException | IOException | ParserConfigurationException e) {
throw new IllegalStateException("Cannot read meta-config from " + metaConfig, e);
}
}
/**
* Reads the meta-configuration and delegates initialization of the current configuration
* context to the {@link MetaConfigReader} instances found in the current
* {@link ServiceContext}.
* @param metaConfig URL for loading the {@code tamaya-config.xml} meta-configuration.
* @return the new configuration instance.
*/
public static Config createConfig(URL metaConfig){
return createConfigBuilder(metaConfig).build();
}
}