Copyright 2014 Netflix, Inc.
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.
/**
 * Copyright 2014 Netflix, Inc.
 *
 * 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 com.netflix.config;

import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Enumeration;
import java.util.Properties;

import org.apache.commons.configuration.ConfigurationException;
import org.apache.commons.configuration.PropertiesConfiguration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.netflix.config.util.ConfigurationUtils;

import com.netflix.config.sources.URLConfigurationSource;

This class helps in loading properties present in a typical web appplication. 1. In a series of application properties file (typically under WEB-INF/conf/*) 2. Every library (JAR) located in the web application's classpath i.e. WEB-INF/lib/*.jar, can contain properties in say META-INF/conf/config.properties This class helps load all the properties into the Default Configuration. In case you would like to load these properties into another Configuration instead, you can use getProperties() to obtain the properties and load these into the Configuration of your choice.
Author:
stonse/**
 * This class helps in loading properties present in a typical web appplication.
 * 
 * 1. In a series of application properties file (typically under
 * WEB-INF/conf/*) 
 * 
 * 2. Every library (JAR) located in the web application's
 * classpath i.e. WEB-INF/lib/*.jar, can contain properties in say
 * META-INF/conf/config.properties
 * 
 * This class helps load all the properties into the Default Configuration.
 * 
 * In case you would like to load these properties into another Configuration
 * instead, you can use {@link #getProperties()} to obtain the properties and
 * load these into the <code>Configuration</code> of your choice.
 * 
 * @author stonse
 * 
 */
public class WebApplicationProperties {

	private static final Logger logger = LoggerFactory
			.getLogger(WebApplicationProperties.class);

	static File appConfFolder = new File("."); // folder where the
												// application properties
												// files are
	static String baseConfigFileName = "config";
	
	static boolean loadLibraryProperties = true;
	
	static String libraryPropertiesResourceRelativePath = ClasspathPropertiesConfiguration.propertiesResourceRelativePath;

	
Initialize. The application should call this method once the Application Folder is set using setAppConfFolder(File, String) method. 
Params:
appConfFolderFromConfig – 
baseConfigFileName – 
loadLibraryProperties – 
propertiesResourceRelativePath – /**
	 * Initialize. The application should call this method once the Application
	 * Folder is set using {@link #setAppConfFolder(File, String)} method.
	 * 
	 * @param appConfFolderFromConfig
	 * @param baseConfigFileName
	 * @param loadLibraryProperties
	 * @param propertiesResourceRelativePath
	 */
	public static void initialize(File appConfFolderFromConfig,
			String baseConfigFileName, boolean loadLibraryProperties,
			String propertiesResourceRelativePath) {
		WebApplicationProperties.appConfFolder = appConfFolderFromConfig;
		WebApplicationProperties.baseConfigFileName = baseConfigFileName;
		WebApplicationProperties.loadLibraryProperties = loadLibraryProperties;
		WebApplicationProperties.libraryPropertiesResourceRelativePath = propertiesResourceRelativePath;
		initialize();
	}
	
	
Initialize. The application should call this method once the Application Folder is set using setAppConfFolder(File, String) method. /**
	 * Initialize.
	 * The application should call this method once the Application Folder is set using {@link #setAppConfFolder(File, String)} method.
	 */
	public static void initialize() {
		try {
			initApplicationProperties();
		} catch (Exception e) {
			logger.error("Unable to load Application Properties", e);
			System.err.println("Unable to load Application Properties");
			e.printStackTrace();
		}

		// should we load the properties in the JAR files?
		if (loadLibraryProperties){
			try {
				initClasspathPropertiesConfiguration();
			} catch (Exception e) {
				logger.error("Unable to load Library Properties", e);
				System.err.println("Unable to load Library Properties");
				e.printStackTrace();
			}
		}

		logger.debug("Properties loaded:" + getProperties());
	}

	protected static void initClasspathPropertiesConfiguration() {
		ClasspathPropertiesConfiguration.initialize();
	}

	protected static void initApplicationProperties()
			throws ConfigurationException, MalformedURLException {
		File appPropFile = new File(appConfFolder + "/" + baseConfigFileName + ".properties");
		File appEnvPropOverrideFile = new File(appConfFolder + "/" + baseConfigFileName +
		 getEnvironment() + ".properties");
		
		 
		// TODO awang, how do we add this to archaius default config?
		PropertiesConfiguration appConf = new PropertiesConfiguration(
				appPropFile);
		// apply env overrides
		PropertiesConfiguration overrideConf = new PropertiesConfiguration(appEnvPropOverrideFile);
		Properties overrideprops = ConfigurationUtils.getProperties(overrideConf);
		for (Object prop: overrideprops.keySet()){
			appConf.setProperty(""+prop, overrideprops.getProperty(""+prop));
		}
		String path = appPropFile.toURI().toURL().toString();
		System.setProperty(URLConfigurationSource.CONFIG_URL, path);
		ConfigurationManager.loadPropertiesFromConfiguration(appConf);

	}

	private static String getEnvironment() {
		String env = System.getProperty("env");
		return env;
	}

	public static File getAppConfFolder() {
		return appConfFolder;
	}

	
The folder where the application's properties files are located.
Params:
appConfFolderFromConfig – 
           the folder as a File object where the
           application's properties files are located
baseConfigFileName – 
           the "base" name of the properties file. For e.g. if you have
           config.properties, config-test.properties, then the value to
           pass in is "config"/**
	 * The folder where the application's properties files are located.
	 * 
	 * @param appConfFolderFromConfig
	 *            the folder as a <code>File</code> object where the
	 *            application's properties files are located
	 * @param baseConfigFileName
	 *            the "base" name of the properties file. For e.g. if you have
	 *            config.properties, config-test.properties, then the value to
	 *            pass in is "config"
	 */
	public static void setAppConfFolder(File appConfFolderFromConfig, String baseConfigFileName) {
		WebApplicationProperties.appConfFolder = appConfFolderFromConfig;
		WebApplicationProperties.baseConfigFileName = baseConfigFileName;
	}
	
	
	
Should we load the Library Properties
/**
	 * Should we load the Library Properties
	 */
	public static boolean shouldLoadLibraryProperties() {
		return loadLibraryProperties;
	}

	
Set this if you would like the ClasspathPropertiesConfiguration to scan the JAR files in the classpath and load those proerties into the default Configuration 
Params:
loadLibraryProperties – /**
	 * Set this if you would like the {@link ClasspathPropertiesConfiguration}
	 * to scan the JAR files in the classpath and load those proerties into the
	 * default Configuration
	 * 
	 * @param loadLibraryProperties
	 */
	public static void setLoadLibraryProperties(boolean loadLibraryProperties) {
		WebApplicationProperties.loadLibraryProperties = loadLibraryProperties;
	}

	
Returns the relative Resource Path of the properties files in the JAR files
/**
	 * Returns the relative Resource Path of the properties files in the JAR files
	 */
	public static String getLibraryPropertiesResourceRelativePath() {
		return libraryPropertiesResourceRelativePath;
	}

	
Please see ClasspathPropertiesConfiguration on Library Properties. This methods sets the relativeResource path 
Params:
libraryPropertiesResourceRelativePath – /**
	 * Please see {@link ClasspathPropertiesConfiguration} on Library Properties.
	 * This methods sets the relativeResource path
	 * @param libraryPropertiesResourceRelativePath
	 */
	public static void setLibraryPropertiesResourceRelativePath(
			String libraryPropertiesResourceRelativePath) {
		WebApplicationProperties.libraryPropertiesResourceRelativePath = libraryPropertiesResourceRelativePath;
	}

	
Returns all the properties presently available
/**
	 * Returns all the properties presently available
	 */
	public static Properties getProperties() {
		return ConfigurationUtils.getProperties(ConfigurationManager.getConfigInstance());
	}
}