gobblin.util.PropertiesUtils.java Source code

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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 gobblin.util;

import java.util.Map;
import java.util.Properties;

import org.apache.commons.lang3.StringUtils;

import com.google.common.base.Preconditions;
import com.google.common.base.Optional;
import com.google.common.collect.ImmutableMap;

/**
 * A utility class for {@link Properties} objects.
 */
public class PropertiesUtils {

    /**
     * Combine a variable number of {@link Properties} into a single {@link Properties}.
     */
    public static Properties combineProperties(Properties... properties) {
        Properties combinedProperties = new Properties();
        for (Properties props : properties) {
            combinedProperties.putAll(props);
        }
        return combinedProperties;
    }

    /**
     * Converts a {@link Properties} object to a {@link Map} where each key is a {@link String}.
     */
    public static Map<String, ?> propsToStringKeyMap(Properties properties) {
        ImmutableMap.Builder<String, Object> mapBuilder = ImmutableMap.builder();
        for (Map.Entry<Object, Object> entry : properties.entrySet()) {
            mapBuilder.put(entry.getKey().toString(), entry.getValue());
        }
        return mapBuilder.build();
    }

    public static boolean getPropAsBoolean(Properties properties, String key, String defaultValue) {
        return Boolean.valueOf(properties.getProperty(key, defaultValue));
    }

    /**
     * Extract all the keys that start with a <code>prefix</code> in {@link Properties} to a new {@link Properties}
     * instance.
     *
     * @param properties the given {@link Properties} instance
     * @param prefix of keys to be extracted
     * @return a {@link Properties} instance
     */
    public static Properties extractPropertiesWithPrefix(Properties properties, Optional<String> prefix) {
        Preconditions.checkNotNull(properties);
        Preconditions.checkNotNull(prefix);

        Properties extractedProperties = new Properties();
        for (Map.Entry<Object, Object> entry : properties.entrySet()) {
            if (StringUtils.startsWith(entry.getKey().toString(), prefix.or(StringUtils.EMPTY))) {
                extractedProperties.put(entry.getKey().toString(), entry.getValue());
            }
        }

        return extractedProperties;
    }
}