code/spi-support/src/main/java/org/apache/tamaya/spisupport/propertysource/JavaConfigurationPropertySource.java

/*
 * 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.spisupport.propertysource;

import org.apache.tamaya.spi.ChangeSupport;
import org.apache.tamaya.spi.ClassloaderAware;
import org.apache.tamaya.spi.PropertySource;
import org.apache.tamaya.spi.PropertyValue;
import org.apache.tamaya.spi.ServiceContextManager;
import org.apache.tamaya.spisupport.PropertySourceComparator;

import java.net.URL;
import java.util.*;

/**
 * Provider which reads all {@value DEFAULT_SIMPLE_PROPERTIES_FILE_NAME} and
 * {@value DEFAULT_XML_PROPERTIES_FILE_NAME} files found in the
 * classpath. By setting
 * {@code tamaya.defaultprops.disable} or {@code tamaya.defaults.disable}
 * as system or environment property this feature can be disabled.
 */
public class JavaConfigurationPropertySource extends BasePropertySource implements ClassloaderAware {
    /**
     * Default location in the classpath, where Tamaya looks for simple line based configuration by default.
     */
    public static final String DEFAULT_SIMPLE_PROPERTIES_FILE_NAME="META-INF/javaconfiguration.properties";

    /**
     * Default location in the classpath, where Tamaya looks for XML based configuration by default.
     */
    public static final String DEFAULT_XML_PROPERTIES_FILE_NAME = "META-INF/javaconfiguration.xml";

    private static final int DEFAULT_ORDINAL = 900;

    private boolean enabled = evaluateEnabled();

    private ClassLoader classLoader;

    private List<PropertySource> propertySources = new ArrayList<>();


    public JavaConfigurationPropertySource(){
        super("resource:META-INF/javaconfiguration.*", DEFAULT_ORDINAL);
    }

    private boolean evaluateEnabled() {
        String value = System.getProperty("tamaya.defaultprops.disable");
        if(value==null){
            value = System.getenv("tamaya.defaultprops.disable");
        }
        if(value==null){
            value = System.getProperty("tamaya.defaults.disable");
        }
        if(value==null){
            value = System.getenv("tamaya.defaults.disable");
        }
        if(value==null){
            return true;
        }
        return value.isEmpty() || !Boolean.parseBoolean(value);
    }

    private List<PropertySource> getPropertySources() {
        return this.propertySources;
    }

    private Collection<? extends PropertySource> loadPropertySourcesByName(String filename, ClassLoader classLoader) {
        List<PropertySource> propertySources = new ArrayList<>();
        Collection<URL> propertyLocations = ServiceContextManager.getServiceContext(classLoader)
                    .getResources(filename);

        for (URL currentUrl:propertyLocations) {
            propertySources.add(new SimplePropertySource(currentUrl));
        }
        propertySources.sort(PropertySourceComparator.getInstance());
        return propertySources;
    }

    public boolean isEnabled() {
        return enabled;
    }

    public void setEnabled(boolean enabled){
        this.enabled = enabled;
    }


    @Override
    public Map<String, PropertyValue> getProperties() {
        if (!isEnabled()) {
            return Collections.emptyMap();
        }
        Map<String,PropertyValue> result = new HashMap<>();
        for(PropertySource ps:getPropertySources()){
            result.putAll(ps.getProperties());
        }
        return result;
    }

    @Override
    public ChangeSupport getChangeSupport(){
        return ChangeSupport.IMMUTABLE;
    }

    @Override
    public String toString() {
        return "JavaConfigurationPropertySource{" +
                "enabled=" + enabled +
                '}';
    }

    @Override
    public void init(ClassLoader classLoader) {
        this.classLoader = Objects.requireNonNull(classLoader);
        propertySources.addAll(loadPropertySourcesByName(DEFAULT_SIMPLE_PROPERTIES_FILE_NAME, classLoader));
        propertySources.addAll(loadPropertySourcesByName(DEFAULT_XML_PROPERTIES_FILE_NAME, classLoader));
        Collections.sort(propertySources, PropertySourceComparator.getInstance());
    }

    @Override
    public ClassLoader getClassLoader() {
        return classLoader;
    }
}