org.kurento.commons.ConfigFilePropertyHolder.java Source code

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Here is the source code for org.kurento.commons.ConfigFilePropertyHolder.java

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/*
 * (C) Copyright 2016 Kurento (http://kurento.org/)
 *
 * 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.kurento.commons;

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.kurento.commons.PropertiesManager.PropertyHolder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.base.Preconditions;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonElement;
import com.google.gson.JsonIOException;
import com.google.gson.JsonObject;
import com.google.gson.JsonPrimitive;
import com.google.gson.JsonSyntaxException;
import com.google.gson.stream.JsonReader;

public class ConfigFilePropertyHolder implements PropertyHolder {

    private static Logger log = LoggerFactory.getLogger(ConfigFilePropertyHolder.class);

    private static final String SINGLE_CONFIG_FILES_PROPERTY = "single.config.file";

    private static Path lastLoadedConfigFilePath;

    private List<ConfigFileObject> loadedConfigFiles;

    private Set<Path> loadedPaths;

    private static final Gson gson = new GsonBuilder().create();

    public static synchronized void configurePropertiesFromConfigFile(Path configFilePath)
            throws JsonSyntaxException, JsonIOException, IOException {

        boolean singleConfigFile = Boolean.getBoolean(SINGLE_CONFIG_FILES_PROPERTY);
        if (singleConfigFile && lastLoadedConfigFilePath != null) {
            log.warn("Trying to load a second config file. The first was {} and the "
                    + "current is {}. Ignoring it.", lastLoadedConfigFilePath, configFilePath);
            return;
        }

        ConfigFilePropertyHolder cfph = null;
        PropertyHolder ph = PropertiesManager.getPropertyHolder();
        if (ph != null && ph instanceof ConfigFilePropertyHolder) {
            cfph = (ConfigFilePropertyHolder) ph;
            if (cfph.loadedPaths != null) {
                if (cfph.loadedPaths.contains(configFilePath)) {
                    log.debug("Trying to load again config file {}. Ignoring it.", configFilePath.toAbsolutePath());
                    return;
                }
            }
        }

        lastLoadedConfigFilePath = configFilePath;

        // FIXME shouldn't this be the first sentence in the method?
        Preconditions.checkNotNull(configFilePath, "configFilePath paramter must be not null.");

        log.debug("Using configuration file in path '{}' ({})", configFilePath,
                configFilePath.getClass().getCanonicalName());

        JsonReader reader = new JsonReader(Files.newBufferedReader(configFilePath, StandardCharsets.UTF_8));

        reader.setLenient(true);

        JsonObject configFile = gson.fromJson(reader, JsonObject.class);

        traceConfigContent(configFile);

        if (cfph == null) {
            cfph = new ConfigFilePropertyHolder();
        }
        cfph.loadedConfigFiles.add(new ConfigFileObject(configFilePath, configFile));
        cfph.loadedPaths.add(configFilePath);

        PropertiesManager.setPropertyHolder(cfph);
    }

    private static void traceConfigContent(JsonObject configFile) {
        if (log.isDebugEnabled()) {
            Gson gs = new GsonBuilder().setPrettyPrinting().disableHtmlEscaping().create();
            String jsonContents = gs.toJson(configFile);
            log.debug("Configuration content: " + jsonContents);
        }
    }

    public ConfigFilePropertyHolder() {
        this.loadedConfigFiles = new ArrayList<ConfigFileObject>();
        this.loadedPaths = new HashSet<Path>();
    }

    @Override
    public String getProperty(String property) {
        String systemProperty = System.getProperty(property);

        if (systemProperty != null) {
            return systemProperty;
        }

        String[] tokens = property.split("\\.");

        int lastTokenNumber = tokens.length - 1;

        // TODO customize search order (by default, it starts from the first loaded file)
        // e.g. system property 'reverseSearch.multi.config.file': if true, start searching in reverse
        if (loadedConfigFiles != null) {

            for (ConfigFileObject configFileObj : loadedConfigFiles) {
                Path currentPath = configFileObj.getConfigFilePath();
                JsonObject currentObject = configFileObj.getConfigFile();

                for (int i = 0; i < tokens.length; i++) {
                    JsonElement element = currentObject.get(tokens[i]);
                    if (element == null) {
                        break; // goto next cfg file
                    }

                    if (i == lastTokenNumber) {
                        log.debug("Found {} in config file {}", property, currentPath.toAbsolutePath());
                        if (element instanceof JsonPrimitive) {
                            return element.getAsString();
                        } else {
                            return element.toString();
                        }
                    }

                    try {
                        currentObject = (JsonObject) element;
                    } catch (ClassCastException e) {
                        break; // goto next cfg file
                    }
                }
            }

        }

        return null;
    }

    public List<ConfigFileObject> getLoadedConfigFiles() {
        return loadedConfigFiles;
    }
}