Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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 * <p/> * http://www.apache.org/licenses/LICENSE-2.0 * <p/> * 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.eagle.metadata.utils; import com.google.common.base.Preconditions; import org.apache.eagle.metadata.model.Configuration; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import javax.xml.bind.JAXBContext; import javax.xml.bind.JAXBException; import javax.xml.bind.Unmarshaller; import java.io.InputStream; import java.io.StringReader; public class ConfigTemplateHelper { private static final Logger LOG = LoggerFactory.getLogger(ConfigTemplateHelper.class); public static Configuration unmarshallFromXmlStream(InputStream inputStream) throws JAXBException { Preconditions.checkNotNull(inputStream, "Input stream is null"); try { JAXBContext jc = JAXBContext.newInstance(Configuration.class); Unmarshaller unmarshaller = jc.createUnmarshaller(); return (Configuration) unmarshaller.unmarshal(inputStream); } catch (Exception ex) { LOG.error("Failed to unmarshall ConfigTemplate from stream", ex); throw ex; } } public static Configuration unmarshallFromResource(String resourceName) throws JAXBException { String source = resourceName; InputStream inputStream = ConfigTemplateHelper.class.getResourceAsStream(resourceName); if (inputStream == null) { source = "/" + resourceName; // LOG.debug("Unable to get resource from {}, retrying with ",resourceName,source); inputStream = ConfigTemplateHelper.class.getResourceAsStream(source); } Preconditions.checkNotNull(inputStream, "Unable to load stream from resource " + source); Configuration configuration = unmarshallFromXmlStream(inputStream); return configuration; } public static Configuration unmarshallFromXMLString(String xmlConfiguration) throws JAXBException { try { JAXBContext jc = JAXBContext.newInstance(Configuration.class); Unmarshaller unmarshaller = jc.createUnmarshaller(); return (Configuration) unmarshaller.unmarshal(new StringReader(xmlConfiguration)); } catch (Exception ex) { LOG.error("Failed to unmarshall ConfigTemplate from string", ex); throw ex; } } }