Java tutorial
/* * Copyright (c) 2014 Red Hat, Inc. and/or its affiliates. * * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * Cheng Fang - Initial API and implementation */ package org.jberet.support.io; import java.io.Serializable; import java.util.List; import javax.batch.api.BatchProperty; import javax.batch.api.chunk.ItemWriter; import javax.enterprise.context.Dependent; import javax.inject.Inject; import javax.inject.Named; import javax.xml.stream.XMLStreamWriter; import com.fasterxml.jackson.core.PrettyPrinter; import com.fasterxml.jackson.core.io.OutputDecorator; import com.fasterxml.jackson.databind.SerializationFeature; import com.fasterxml.jackson.dataformat.xml.JacksonXmlModule; import com.fasterxml.jackson.dataformat.xml.ser.ToXmlGenerator; import org.jberet.support._private.SupportLogger; import org.jberet.support._private.SupportMessages; /** * An implementation of {@code javax.batch.api.chunk.ItemWriter} that writes a list of same-typed objects to XML resource. * Each object is written as a sub-element of the target XML resource. The XML root element is specified with the * injected batch artifact properties {@link #rootElementName}, {@link #rootElementNamespaceURI}, and * {@link #rootElementPrefix}. * * @see XmlItemReader * @see XmlItemReaderWriterBase * @since 1.0.2 */ @Named @Dependent public class XmlItemWriter extends XmlItemReaderWriterBase implements ItemWriter { /** * Instructs this class, when the target XML resource already * exists, whether to append to, or overwrite the existing resource, or fail. Valid values are {@code append}, * {@code overwrite}, and {@code failIfExists}. Optional property, and defaults to {@code append}. */ @Inject @BatchProperty protected String writeMode; /** * Whether use wrapper for indexed (List, array) properties or not, if there are no explicit annotations. * Optional property, valid values are "true" and "false", and defaults to "true". * * @see "com.fasterxml.jackson.dataformat.xml.JacksonXmlModule#setDefaultUseWrapper(boolean)" * @see "com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlElementWrapper" */ @Inject @BatchProperty protected String defaultUseWrapper; /** * Local name of the output XML root element. Required property. * * @see "javax.xml.stream.XMLStreamWriter#writeStartElement" */ @Inject @BatchProperty protected String rootElementName; /** * The prefix of the XML root element tag. Optional property and defaults to null. * * @see "javax.xml.stream.XMLStreamWriter#writeStartElement(java.lang.String, java.lang.String, java.lang.String)" */ @Inject @BatchProperty protected String rootElementPrefix; /** * The namespaceURI of the prefix to use. Optional property and defaults to null. * @see "javax.xml.stream.XMLStreamWriter#writeStartElement(java.lang.String, java.lang.String, java.lang.String)" * @see "javax.xml.stream.XMLStreamWriter#writeStartElement(java.lang.String, java.lang.String)" */ @Inject @BatchProperty protected String rootElementNamespaceURI; /** * The fully-qualified name of a class implementing {@code com.fasterxml.jackson.core.PrettyPrinter}, which implements * pretty printer functionality, such as indentation. Optional property and defaults to null (default pretty printer * is used). * * @see "com.fasterxml.jackson.core.PrettyPrinter" * @see "com.fasterxml.jackson.dataformat.xml.ser.ToXmlGenerator#setPrettyPrinter(com.fasterxml.jackson.core.PrettyPrinter)" */ @Inject @BatchProperty protected Class prettyPrinter; /** * The fully-qualified name of a class implementing {@code com.fasterxml.jackson.core.io.OutputDecorator}, which * can be used to decorate output destinations. Optional property and defaults to null. * * @see "com.fasterxml.jackson.core.JsonFactory#setOutputDecorator(com.fasterxml.jackson.core.io.OutputDecorator)" * @see "com.fasterxml.jackson.core.io.OutputDecorator" */ @Inject @BatchProperty protected Class outputDecorator; protected ToXmlGenerator toXmlGenerator; private XMLStreamWriter staxWriter; @Override public void open(final Serializable checkpoint) throws Exception { SupportLogger.LOGGER.tracef("Open XmlItemWriter with checkpoint %s, which is ignored for XmlItemWriter.%n", checkpoint); super.initXmlFactory(); if (outputDecorator != null) { xmlFactory.setOutputDecorator((OutputDecorator) outputDecorator.newInstance()); } xmlMapper.configure(SerializationFeature.WRAP_ROOT_VALUE, false); toXmlGenerator = xmlFactory.createGenerator(getOutputStream(writeMode)); SupportLogger.LOGGER.openingResource(resource, this.getClass()); if (prettyPrinter == null) { toXmlGenerator.useDefaultPrettyPrinter(); } else { toXmlGenerator.setPrettyPrinter((PrettyPrinter) prettyPrinter.newInstance()); } staxWriter = toXmlGenerator.getStaxWriter(); if (!this.skipWritingHeader) { staxWriter.writeStartDocument(); } staxWriter.writeCharacters(NEW_LINE); if (rootElementName == null || rootElementName.isEmpty()) { throw SupportMessages.MESSAGES.invalidReaderWriterProperty(null, rootElementName, "rootElementName"); } if (rootElementPrefix == null || rootElementPrefix.isEmpty()) { if (rootElementNamespaceURI == null || rootElementNamespaceURI.isEmpty()) { staxWriter.writeStartElement(rootElementName); } else { staxWriter.writeStartElement(rootElementNamespaceURI, rootElementName); } } else { if (rootElementNamespaceURI == null || rootElementNamespaceURI.isEmpty()) { throw SupportMessages.MESSAGES.invalidReaderWriterProperty(null, rootElementNamespaceURI, "rootElementNamespaceURI"); } else { staxWriter.writeStartElement(rootElementPrefix, rootElementName, rootElementNamespaceURI); } } } @Override public void writeItems(final List<Object> items) throws Exception { for (final Object o : items) { staxWriter.writeCharacters(NEW_LINE); toXmlGenerator.writeObject(o); } toXmlGenerator.flush(); } @Override public Serializable checkpointInfo() throws Exception { return null; } @Override public void close() throws Exception { if (toXmlGenerator != null) { SupportLogger.LOGGER.closingResource(resource, this.getClass()); staxWriter.writeCharacters(NEW_LINE); staxWriter.writeEndDocument(); toXmlGenerator.close(); toXmlGenerator = null; } } @Override protected void initXmlModule() { if (defaultUseWrapper != null) { if (defaultUseWrapper.equals("false")) { xmlModule = new JacksonXmlModule(); xmlModule.setDefaultUseWrapper(false); } else if (defaultUseWrapper.equals("true")) { //default value is already true, so nothing to do } else { throw SupportMessages.MESSAGES.invalidReaderWriterProperty(null, defaultUseWrapper, "defaultUseWrapper"); } } } }