org.apache.aurora.common.util.BuildInfo.java Source code

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Here is the source code for org.apache.aurora.common.util.BuildInfo.java

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/**
 * 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 org.apache.aurora.common.util;

import java.io.InputStream;
import java.util.Map;
import java.util.Properties;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Maps;

import org.apache.aurora.common.base.MorePreconditions;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import static java.util.Objects.requireNonNull;

/**
 * Handles loading of a build properties file, and provides keys to look up known values in the
 * properties.
 */
public class BuildInfo {

    private static final Logger LOG = LoggerFactory.getLogger(BuildInfo.class);

    private static final String DEFAULT_BUILD_PROPERTIES_PATH = "build.properties";

    private final String resourcePath;

    private Map<String, String> properties = ImmutableMap.of();

    /**
     * Creates a build info container that will use the default properties file path.
     */
    public BuildInfo() {
        this(DEFAULT_BUILD_PROPERTIES_PATH);
    }

    /**
     * Creates a build info container, reading from the given path.
     *
     * @param resourcePath The resource path to read build properties from.
     */
    public BuildInfo(String resourcePath) {
        this.resourcePath = MorePreconditions.checkNotBlank(resourcePath);
        fetchProperties();
    }

    @VisibleForTesting
    public BuildInfo(Map<String, String> properties) {
        this.resourcePath = null;
        this.properties = requireNonNull(properties);
    }

    private void fetchProperties() {
        LOG.info("Fetching build properties from " + resourcePath);
        InputStream in = ClassLoader.getSystemResourceAsStream(resourcePath);
        if (in == null) {
            LOG.warn("Failed to fetch build properties from " + resourcePath);
            return;
        }

        try {
            Properties buildProperties = new Properties();
            buildProperties.load(in);
            properties = Maps.fromProperties(buildProperties);
        } catch (Exception e) {
            LOG.warn("Failed to load properties file " + resourcePath, e);
        }
    }

    /**
     * Fetches the properties stored in the resource location.
     *
     * @return A map of the loaded properties, or an empty Map if there was a problem loading
     *    the specified properties resource.
     */
    public Map<String, String> getProperties() {
        return properties;
    }
}