# FilePropertyLoader.java

    /*
     * Copyright (c) 2019, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
     *
     * 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.synapse.commons.util;

    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.synapse.commons.SynapseCommonsException;

    import java.io.File;
    import java.io.FileInputStream;
    import java.io.InputStream;
    import java.io.IOException;
    import java.util.HashMap;
    import java.util.Map;
    import java.util.Properties;

    /**
     * File Property loader can be used to load the file property variables.
     */
    public class FilePropertyLoader {

        private static final Log LOG = LogFactory.getLog(FilePropertyLoader.class);
        private static final String CONF_LOCATION = "conf.location";
        public static final String FILE_PROPERTY_PATH = "properties.file.path";
        private static final String DEFAULT_PROPERTY_FILE = "file.properties";
        private Map propertyMap;

        private static FilePropertyLoader fileLoaderInstance;

        public static FilePropertyLoader getInstance() {
            if ( null == fileLoaderInstance) {
                fileLoaderInstance = new FilePropertyLoader();
                fileLoaderInstance.loadPropertiesFile();
            }
            return fileLoaderInstance;
        }

        public String getValue(String input) {
            return (String) propertyMap.get(input);
        }

        private void loadPropertiesFile() throws SynapseCommonsException {

            String filePath = System.getProperty(FILE_PROPERTY_PATH);

            if ( null == filePath || filePath.isEmpty()) {
                throw new SynapseCommonsException(FILE_PROPERTY_PATH + " is empty or null");
            }
            if (("default").equals(filePath)) {
                filePath = System.getProperty(CONF_LOCATION) + File.separator + DEFAULT_PROPERTY_FILE;
            }

            File file = new File(filePath);
            boolean isFileExists = file.exists();

            if (isFileExists) {
                try (InputStream in = new FileInputStream(filePath)) {
                    Properties rawProps = new Properties();
                    propertyMap = new HashMap();
                    rawProps.load(in);
                    for (Map.Entry<Object, Object> propertyEntry : rawProps.entrySet()) {
                        String strValue = (String) propertyEntry.getValue();
                        propertyMap.put(propertyEntry.getKey(), strValue);
                    }
                    if (LOG.isDebugEnabled()) {
                        LOG.debug("Loaded factory properties from " + filePath + ": " + propertyMap);
                    }
                } catch (IOException ex) {
                    throw new SynapseCommonsException("Failed to read " + filePath, ex);
                }
            } else {
                throw new SynapseCommonsException("File cannot found in " + filePath);
            }
        }
    }