ai.general.interbot.ConfigFiles.java Source code

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Here is the source code for ai.general.interbot.ConfigFiles.java

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/* General AI - Interbot
 * Copyright (C) 2013 Tuna Oezer, General AI.
 * See license.txt for copyright information.
 */

package ai.general.interbot;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.LogManager;

import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * Loads, caches and saves configuration files.
 *
 * Depending on whether the application is run from the command line or as a web app, the location
 * of the configuration files will change. This class loads or saves the configuration files from
 * the location that is appropriate for the context in which the application is run.
 *
 * All configuration files have JSON format. The configuration files are parsed into an object
 * using a JSON parser. Updated configuration objects are written as JSON files.
 *
 * ConfigFiles is a singleton class.
 */
public class ConfigFiles {

    /**
     * ConfigFiles is singleton. A ConfigFiles instance can be obtained via {@link #Instance}.
     */
    private ConfigFiles() {
        configs_ = new HashMap<String, Object>();
    }

    /**
     * If the specified configuration file has not been already loaded, loads the configuration file.
     * Once the file is loaded, it is cached by ConfigFiles, such that future requests for loading
     * the file will be served from the cache.
     *
     * The filename should specify only the configuration filename.
     * The file will be loaded from the configuration file directory that is appropriate for the
     * current context.
     *
     * The file must be a JSON file. If the .json extension is not specified in the filename, it
     * will be appended to the filename.
     *
     * The loaded file is parsed into an instance of config_type.
     *
     * If the config file cannot be loaded, this method returns null.
     *
     * @param filename The name of the configuration file, excluding extension and directory.
     * @param config_type The class that defines the configuration options specified in the file.
     * @return The loaded configuration as an instance of the config_type class or null.
     */
    public <T> T load(String filename, Class<T> config_type) {
        if (!filename.endsWith(".json")) {
            filename = filename + ".json";
        }
        if (configs_.containsKey(filename)) {
            @SuppressWarnings("unchecked")
            T config = (T) configs_.get(filename);
            return config;
        } else {
            ObjectMapper json_parser = new ObjectMapper();
            try {
                T config = json_parser.readValue(new File(InterbotPaths.getConfigDirectory() + filename),
                        config_type);
                configs_.put(filename, config);
                return config;
            } catch (IOException e) {
                log.catching(Level.DEBUG, e);
                return null;
            }
        }
    }

    /**
     * Saves a configuration file. The filename should specify only the configuration filename.
     * The file will be saved to the configuration file directory that is appropriate for the
     * current context.
     *
     * The configuration object will be saved in JSON format. The configuration object must be a
     * POJO class that is serializable into JSON.
     *
     * If the .json extension is not specified in the filename, it will be appended to the filename.
     *
     * @param filename The name of the configuration file, excluding extension and directory.
     * @param configuration The object representing the configuration to be saved.
     * @return True if the file was successfully saved.
     */
    public boolean save(String filename, Object configuration) {
        if (!filename.endsWith(".json")) {
            filename = filename + ".json";
        }
        ObjectMapper json_generator = new ObjectMapper();
        try {
            json_generator.writeValue(new File(InterbotPaths.getConfigDirectory() + filename), configuration);
            return true;
        } catch (IOException e) {
            log.catching(Level.DEBUG, e);
            return false;
        }
    }

    public final static ConfigFiles Instance = new ConfigFiles();
    private static Logger log = LogManager.getLogger();

    private HashMap<String, Object> configs_; // Loaded configurations.
}