Created
October 27, 2019 21:41
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Lightweight property manager for java that can handle ${place.holders} and resolves as a singleton returning a HashMap<String, String>
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| /* | |
| * PropertyManager | |
| * | |
| * Copyright (C) 2019 matthias.dirickx@outlook.com | |
| * | |
| * This program 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. | |
| * | |
| * This program 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 this program. If not, see <http://www.gnu.org/licenses/>. | |
| */ | |
| package propertymanager; | |
| import java.io.IOException; | |
| import java.io.InputStream; | |
| import java.util.HashMap; | |
| import java.util.Map; | |
| import java.util.Properties; | |
| import java.util.regex.Matcher; | |
| import java.util.regex.Pattern; | |
| /** | |
| * Static property manager. | |
| * The rudimentary property manager loads a file from resources (root). | |
| * Name : qcclient.properties | |
| * | |
| * The properties are loaded to a map and resolved. | |
| * | |
| * If any properties are added at runtime you need to call resolveProperties() if the properties contain placeholders. | |
| * | |
| * There are three public accessors. | |
| * - getProperty() | |
| * - setProperty() | |
| * - resolveProperties() | |
| * | |
| * Get a property with getProperty(name). | |
| * Set a property with setProperty(name). | |
| * | |
| * If there are properties containing placeholders, | |
| * make sure to call resolveProperties() to resolve all of the property placeholders. | |
| */ | |
| public class PropertyManager { | |
| private static final String PROP_FIND_REGEX = "\\$\\{[^\\{\\}]*\\}"; | |
| private static final Pattern pattern = Pattern.compile(PROP_FIND_REGEX); | |
| private static PropertyManager pr; | |
| private Properties props; | |
| private Map<String, String> propsMap; | |
| private PropertyManager() { | |
| props = new Properties(); | |
| InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream("qcclient.properties"); | |
| try { | |
| props.load(inputStream); | |
| } catch(IOException e) { | |
| e.printStackTrace(); | |
| } | |
| propsMap = new HashMap<>(); | |
| } | |
| private void pushPropsToMap() { | |
| for(String key : props.stringPropertyNames()) { | |
| propsMap.put( | |
| key, | |
| resolveProperty(props.getProperty(key)) | |
| ); | |
| } | |
| } | |
| /** | |
| * Recursive function to resolve the property placeholders. | |
| * @param propValue | |
| * @return String (resolved property without placeholders) | |
| */ | |
| private String resolveProperty(String propValue) { | |
| String resolvedProperty = propValue; | |
| Matcher matcher = pattern.matcher(propValue); | |
| if(matcher.find(0)) { | |
| String match = matcher.group(); | |
| resolvedProperty = resolvedProperty.replace(match, getProperty(match.substring(2, match.length()-1))); | |
| Matcher nestedMatcher = pattern.matcher(resolvedProperty); | |
| if(nestedMatcher.find(0)) { | |
| resolvedProperty = resolveProperty(resolvedProperty); | |
| } | |
| } | |
| return resolvedProperty; | |
| } | |
| private static synchronized Map<String, String> getProperties() { | |
| if(pr == null) { | |
| synchronized (PropertyManager.class) { | |
| if(pr == null) { | |
| pr = new PropertyManager(); | |
| pr.pushPropsToMap(); | |
| resolveProperties(); | |
| } | |
| } | |
| } | |
| return pr.propsMap; | |
| } | |
| /** | |
| * Gets a property from the hashmap stored in the PropertyManager singleton. | |
| * @param name | |
| * @return | |
| */ | |
| public static String getProperty(String name) { | |
| return getProperties().get(name); | |
| } | |
| /** | |
| * Set property in the hasmap stroed in the PropertyManager singleton. | |
| * Setting a value with setProperty does NOT store this property in the .properties file. | |
| * @param name | |
| * @param value | |
| */ | |
| public static void setProperty(String name, String value) { | |
| getProperties().put(name, value); | |
| } | |
| /** | |
| * Resolve all properties that are stored in the hashmap in the PropertyManager singleton. | |
| */ | |
| public static void resolveProperties() { | |
| for(String key : pr.propsMap.keySet()) { | |
| String resolvedProp = pr.resolveProperty(getProperty(key)); | |
| pr.propsMap.put(key, resolvedProp); | |
| } | |
| } | |
| } |
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It can handle regular things.
Things will go wrong when you have a placeholder containing either $, { or }.
Also circular references are not checked!