ConfigurationProperties.java

/*******************************************************************************
 * Copyright (c) 2012-2017 Codenvy, S.A.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Codenvy, S.A. - initial API and implementation
 *******************************************************************************/
package org.eclipse.che.inject;

import com.google.inject.Binding;
import com.google.inject.Injector;
import com.google.inject.Key;

import javax.inject.Inject;
import javax.inject.Provider;
import javax.inject.Singleton;
import java.lang.annotation.Annotation;
import java.util.HashMap;
import java.util.Map;
import java.util.regex.Pattern;

/**
 * Helper for getting set of configuration properties by name's pattern.
 * <pre>{@code
 * public class Service {
 *     private Map<String, String> configuration;
 *     @Inject
 *     Service(ConfigurationProperties configurationProperties) {
 *         configuration = configurationProperties.getProperties("test.*");
 *     }
 *     ...
 * }
 * }</pre>
 *
 * @author andrew00x
 */
@Singleton
public class ConfigurationProperties {
    private final Provider<Injector> injectorProvider;

    @Inject
    ConfigurationProperties(Provider<Injector> injectorProvider) {
        this.injectorProvider = injectorProvider;
    }

    public Map<String, String> getProperties(String namePattern) {
        final Pattern pattern = Pattern.compile(namePattern);
        final Map<String, String> result = new HashMap<>();
        for (Map.Entry<Key<?>, Binding<?>> keyBindingEntry : injectorProvider.get().getAllBindings().entrySet()) {
            final Key<?> key = keyBindingEntry.getKey();
            final Annotation annotation = key.getAnnotation();
            if (annotation instanceof com.google.inject.name.Named && key.getTypeLiteral().getRawType() == String.class) {
                final String name = ((com.google.inject.name.Named)annotation).value();
                if (name != null && pattern.matcher(name).matches()) {
                    final String value = (String)keyBindingEntry.getValue().getProvider().get();
                    result.put(name, value);
                }
            }
        }
        return result;
    }
}