001/*-
002 * #%L
003 * HAPI FHIR - Core Library
004 * %%
005 * Copyright (C) 2014 - 2024 Smile CDR, Inc.
006 * %%
007 * Licensed under the Apache License, Version 2.0 (the "License");
008 * you may not use this file except in compliance with the License.
009 * You may obtain a copy of the License at
010 *
011 *      http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing, software
014 * distributed under the License is distributed on an "AS IS" BASIS,
015 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
016 * See the License for the specific language governing permissions and
017 * limitations under the License.
018 * #L%
019 */
020package ca.uhn.fhir.util;
021
022import org.slf4j.Logger;
023import org.slf4j.LoggerFactory;
024
025import java.io.Reader;
026import java.io.StringReader;
027
028public class XmlDetectionUtil {
029
030        private static final Logger ourLog = LoggerFactory.getLogger(XmlDetectionUtil.class);
031        private static Boolean ourStaxPresent;
032
033        /**
034         * This method will return <code>true</code> if a StAX XML parsing library is present
035         * on the classpath
036         */
037        public static boolean isStaxPresent() {
038                Boolean retVal = ourStaxPresent;
039                if (retVal == null) {
040                        try {
041                                Class.forName("javax.xml.stream.events.XMLEvent");
042                                Class<?> xmlUtilClazz = Class.forName("ca.uhn.fhir.util.XmlUtil");
043                                xmlUtilClazz.getMethod("createXmlReader", Reader.class).invoke(xmlUtilClazz, new StringReader(""));
044                                ourStaxPresent = Boolean.TRUE;
045                                retVal = Boolean.TRUE;
046                        } catch (Throwable t) {
047                                ourLog.info("StAX not detected on classpath, XML processing will be disabled");
048                                ourStaxPresent = Boolean.FALSE;
049                                retVal = Boolean.FALSE;
050                        }
051                }
052                return retVal;
053        }
054}