~~~ /** * Copyright 2009-2016 the original author or authors. * * 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.ibatis.parsing; import java.util.Properties; /** * @author Clinton Begin * @author Kazuki Shimizu */ public class PropertyParser { private static final String KEY_PREFIX = "org.apache.ibatis.parsing.PropertyParser."; /** * The special property key that indicate whether enable a default value on placeholder. * <p> * The default value is {@code false} (indicate disable a default value on placeholder) * If you specify the {@code true}, you can specify key and default value on placeholder (e.g. {@code ${db.username:postgres}}). * </p> * @since 3.4.2 */ public static final String KEY_ENABLE_DEFAULT_VALUE = KEY_PREFIX + "enable-default-value"; /** * The special property key that specify a separator for key and default value on placeholder. * <p> * The default separator is {@code ":"}. * </p> * @since 3.4.2 */ public static final String KEY_DEFAULT_VALUE_SEPARATOR = KEY_PREFIX + "default-value-separator"; private static final String ENABLE_DEFAULT_VALUE = "false"; private static final String DEFAULT_VALUE_SEPARATOR = ":"; private PropertyParser() { // Prevent Instantiation } public static String parse(String string, Properties variables) { VariableTokenHandler handler = new VariableTokenHandler(variables); GenericTokenParser parser = new GenericTokenParser("${", "}", handler); return parser.parse(string); } private static class VariableTokenHandler implements TokenHandler { private final Properties variables; private final boolean enableDefaultValue; private final String defaultValueSeparator; private VariableTokenHandler(Properties variables) { this.variables = variables; this.enableDefaultValue = Boolean.parseBoolean(getPropertyValue(KEY_ENABLE_DEFAULT_VALUE, ENABLE_DEFAULT_VALUE)); this.defaultValueSeparator = getPropertyValue(KEY_DEFAULT_VALUE_SEPARATOR, DEFAULT_VALUE_SEPARATOR); } private String getPropertyValue(String key, String defaultValue) { return (variables == null) ? defaultValue : variables.getProperty(key, defaultValue); } @Override public String handleToken(String content) { if (variables != null) { String key = content; if (enableDefaultValue) { final int separatorIndex = content.indexOf(defaultValueSeparator); String defaultValue = null; if (separatorIndex >= 0) { key = content.substring(0, separatorIndex); defaultValue = content.substring(separatorIndex + defaultValueSeparator.length()); } if (defaultValue != null) { return variables.getProperty(key, defaultValue); } } if (variables.containsKey(key)) { return variables.getProperty(key); } } return "${" + content + "}"; } } } ~~~