com.comcast.cats.service.util.YAMLUtils.java Source code

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Here is the source code for com.comcast.cats.service.util.YAMLUtils.java

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/**
 * Copyright 2014 Comcast Cable Communications Management, LLC
 *
 * This file is part of CATS.
 *
 * CATS is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * CATS is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with CATS.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.comcast.cats.service.util;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;

import org.apache.commons.lang.IllegalClassException;
import org.apache.log4j.Logger;
import org.yaml.snakeyaml.Yaml;
import org.yaml.snakeyaml.constructor.Constructor;
import org.yaml.snakeyaml.representer.Representer;

/**
 * Provides a util to handle YAML files.
 * 
 * @author skurup00c
 * 
 */
public class YAMLUtils {

    private static Logger logger = Logger.getLogger(YAMLUtils.class);

    @SuppressWarnings("unchecked")
    public static synchronized <T> T loadFromYAML(String filePath, T resultObject, Constructor constructor)
            throws IllegalClassException, IOException {
        Yaml yaml;
        FileInputStream fileIS = null;

        if (constructor != null) {
            yaml = new Yaml(constructor);
        } else {
            yaml = new Yaml();
        }
        try {
            fileIS = new FileInputStream(filePath);
            resultObject = (T) yaml.load(fileIS);
        } catch (FileNotFoundException exception) {
            File file = new File(filePath);
            file.createNewFile(); // create file if one does not exist.
            fileIS = new FileInputStream(filePath);
            resultObject = (T) yaml.load(fileIS);
        } catch (ClassCastException e) {
            logger.warn(
                    "YAML content found at " + filePath + " does not conform to passed object " + e.getMessage());
            throw new IllegalClassException(
                    "YAML content found at " + filePath + " does not conform to passed object " + e.getMessage());
        } finally {
            if (fileIS != null) {
                fileIS.close();
            }
        }

        return resultObject;
    }

    public static synchronized <T> void saveAsYAML(String filePath, T objectToSave, Representer representer)
            throws FileNotFoundException {
        if (objectToSave != null) {
            Yaml yaml;
            FileWriter fw = null;
            if (representer == null) {
                yaml = new Yaml();
            } else {
                yaml = new Yaml(representer);
            }
            try {

                File file = new File(filePath);
                file.createNewFile(); // create file if one does not exist.

                fw = new FileWriter(filePath);
                yaml.dump(objectToSave, fw);
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                if (fw != null) {
                    try {
                        fw.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }
}