001package ca.uhn.fhir.util;
002
003/*-
004 * #%L
005 * HAPI FHIR - Core Library
006 * %%
007 * Copyright (C) 2014 - 2022 Smile CDR, Inc.
008 * %%
009 * Licensed under the Apache License, Version 2.0 (the "License");
010 * you may not use this file except in compliance with the License.
011 * You may obtain a copy of the License at
012 *
013 *      http://www.apache.org/licenses/LICENSE-2.0
014 *
015 * Unless required by applicable law or agreed to in writing, software
016 * distributed under the License is distributed on an "AS IS" BASIS,
017 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
018 * See the License for the specific language governing permissions and
019 * limitations under the License.
020 * #L%
021 */
022
023import org.slf4j.Logger;
024import org.slf4j.LoggerFactory;
025
026import java.io.Reader;
027import java.io.StringReader;
028
029public class XmlDetectionUtil {
030
031        private static final Logger ourLog = LoggerFactory.getLogger(XmlDetectionUtil.class);
032        private static Boolean ourStaxPresent;
033
034        /**
035         * This method will return <code>true</code> if a StAX XML parsing library is present
036         * on the classpath
037         */
038        public static boolean isStaxPresent() {
039                Boolean retVal = ourStaxPresent;
040                if (retVal == null) {
041                        try {
042                                Class.forName("javax.xml.stream.events.XMLEvent");
043                                Class<?> xmlUtilClazz = Class.forName("ca.uhn.fhir.util.XmlUtil");
044                                xmlUtilClazz.getMethod("createXmlReader", Reader.class).invoke(xmlUtilClazz, new StringReader(""));
045                                ourStaxPresent = Boolean.TRUE;
046                                retVal = Boolean.TRUE;
047                        } catch (Throwable t) {
048                                ourLog.info("StAX not detected on classpath, XML processing will be disabled");
049                                ourStaxPresent = Boolean.FALSE;
050                                retVal = Boolean.FALSE;
051                        }
052                }
053                return retVal;
054        }
055
056        
057}