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 * * 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.axiom.om.util; import org.apache.axiom.om.OMException; import org.apache.axiom.om.OMXMLStreamReader; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import javax.activation.DataHandler; import javax.xml.namespace.NamespaceContext; import javax.xml.namespace.QName; import javax.xml.stream.Location; import javax.xml.stream.XMLStreamConstants; import javax.xml.stream.XMLStreamException; import java.util.Stack; // TODO: this needs reformatting; the (generated) Javadoc is unreadable! /** * There are several places in the code where events are passed from * a source to a consumer using XMLStreamReader events. * * OMXMLStreamReader (impl)--> consumer of XMLStreamReader events * * This simple class can be interjected as a filter and used to do some simple validation. * Validating the events coming from source (impl) can help find and correct errors * when they occur. Otherwise the errors may be caught much further downstream and hard to fix. * * OMXMLStreamReader (impl)--> OMXMLStreamReaderValiator-> consumer of XMLStreamReader events * * * In the initial version, the XMStreamValidator ensures that the start element events match the * end element events. * * @see org.apache.axiom.om.OMElement#getXMLStreamReader(boolean) */ public class OMXMLStreamReaderValidator implements OMXMLStreamReader { private static Log log = LogFactory.getLog(OMXMLStreamReaderValidator.class); private static boolean IS_DEBUG_ENABLED = log.isDebugEnabled(); private static boolean IS_ADV_DEBUG_ENABLED = false; // Turn this on to trace every event private final OMXMLStreamReader delegate; // Actual XMLStreamReader implementation private boolean throwExceptions = false; // Indicates whether OMException should be thrown if errors are disovered private Stack stack = new Stack(); // Stack keeps track of the nested element QName /** * @param delegate XMLStreamReader to validate * @param throwExceptions (true if exceptions should be thrown when errors are encountered) */ public OMXMLStreamReaderValidator(OMXMLStreamReader delegate, boolean throwExceptions) { super(); this.delegate = delegate; this.throwExceptions = throwExceptions; } public int next() throws XMLStreamException { int event = delegate.next(); logParserState(); // Make sure that the start element and end element events match. // Mismatched events are a key indication that the delegate stream reader is // broken or corrupted. switch (event) { case XMLStreamConstants.START_ELEMENT: stack.push(delegate.getName()); break; case XMLStreamConstants.END_ELEMENT: QName delegateQName = delegate.getName(); if (stack.isEmpty()) { reportMismatchedEndElement(null, delegateQName); } else { QName expectedQName = (QName) stack.pop(); if (!expectedQName.equals(delegateQName)) { reportMismatchedEndElement(expectedQName, delegateQName); } } break; default: } return event; } /** * Report a mismatched end element. * @param expectedQName * @param delegateQName */ private void reportMismatchedEndElement(QName expectedQName, QName delegateQName) { String text = null; if (expectedQName == null) { text = "An END_ELEMENT event for " + delegateQName + " was encountered, but the START_ELEMENT stack is empty."; } else { text = "An END_ELEMENT event for " + delegateQName + " was encountered, but this doesn't match the corresponding START_ELEMENT " + expectedQName + " event."; } if (IS_DEBUG_ENABLED) { log.debug(text); } if (throwExceptions) { throw new OMException(text); } } public void close() throws XMLStreamException { delegate.close(); } public int getAttributeCount() { return delegate.getAttributeCount(); } public String getAttributeLocalName(int arg0) { return delegate.getAttributeLocalName(arg0); } public QName getAttributeName(int arg0) { return delegate.getAttributeName(arg0); } public String getAttributeNamespace(int arg0) { return delegate.getAttributeNamespace(arg0); } public String getAttributePrefix(int arg0) { return delegate.getAttributePrefix(arg0); } public String getAttributeType(int arg0) { return delegate.getAttributeType(arg0); } public String getAttributeValue(int arg0) { return delegate.getAttributeValue(arg0); } public String getAttributeValue(String arg0, String arg1) { return delegate.getAttributeValue(arg0, arg1); } public String getCharacterEncodingScheme() { return delegate.getCharacterEncodingScheme(); } public String getElementText() throws XMLStreamException { return delegate.getElementText(); } public String getEncoding() { return delegate.getEncoding(); } public int getEventType() { return delegate.getEventType(); } public String getLocalName() { return delegate.getLocalName(); } public Location getLocation() { return delegate.getLocation(); } public QName getName() { return delegate.getName(); } public NamespaceContext getNamespaceContext() { return delegate.getNamespaceContext(); } public int getNamespaceCount() { return delegate.getNamespaceCount(); } public String getNamespacePrefix(int arg0) { return delegate.getNamespacePrefix(arg0); } public String getNamespaceURI() { return delegate.getNamespaceURI(); } public String getNamespaceURI(int arg0) { return delegate.getNamespaceURI(arg0); } public String getNamespaceURI(String arg0) { return delegate.getNamespaceURI(arg0); } public String getPIData() { return delegate.getPIData(); } public String getPITarget() { return delegate.getPITarget(); } public String getPrefix() { return delegate.getPrefix(); } public Object getProperty(String arg0) throws IllegalArgumentException { return delegate.getProperty(arg0); } public String getText() { return delegate.getText(); } public char[] getTextCharacters() { return delegate.getTextCharacters(); } public int getTextCharacters(int arg0, char[] arg1, int arg2, int arg3) throws XMLStreamException { return delegate.getTextCharacters(arg0, arg1, arg2, arg3); } public int getTextLength() { return delegate.getTextLength(); } public int getTextStart() { return delegate.getTextStart(); } public String getVersion() { return delegate.getVersion(); } public boolean hasName() { return delegate.hasName(); } public boolean hasNext() throws XMLStreamException { return delegate.hasNext(); } public boolean hasText() { return delegate.hasText(); } public boolean isAttributeSpecified(int arg0) { return delegate.isAttributeSpecified(arg0); } public boolean isCharacters() { return delegate.isCharacters(); } public boolean isEndElement() { return delegate.isEndElement(); } public boolean isStandalone() { return delegate.isStandalone(); } public boolean isStartElement() { return delegate.isStartElement(); } public boolean isWhiteSpace() { return delegate.isWhiteSpace(); } public int nextTag() throws XMLStreamException { return delegate.nextTag(); } public void require(int arg0, String arg1, String arg2) throws XMLStreamException { delegate.require(arg0, arg1, arg2); } public boolean standaloneSet() { return delegate.standaloneSet(); } /** * Dump the current event of the delegate. */ protected void logParserState() { if (IS_ADV_DEBUG_ENABLED) { int currentEvent = delegate.getEventType(); switch (currentEvent) { case XMLStreamConstants.START_ELEMENT: log.trace("START_ELEMENT: "); log.trace(" QName: " + delegate.getName()); break; case XMLStreamConstants.START_DOCUMENT: log.trace("START_DOCUMENT: "); break; case XMLStreamConstants.CHARACTERS: log.trace("CHARACTERS: "); log.trace("[" + delegate.getText() + "]"); break; case XMLStreamConstants.CDATA: log.trace("CDATA: "); log.trace("[" + delegate.getText() + "]"); break; case XMLStreamConstants.END_ELEMENT: log.trace("END_ELEMENT: "); log.trace(" QName: " + delegate.getName()); break; case XMLStreamConstants.END_DOCUMENT: log.trace("END_DOCUMENT: "); break; case XMLStreamConstants.SPACE: log.trace("SPACE: "); log.trace("[" + delegate.getText() + "]"); break; case XMLStreamConstants.COMMENT: log.trace("COMMENT: "); log.trace("[" + delegate.getText() + "]"); break; case XMLStreamConstants.DTD: log.trace("DTD: "); log.trace("[" + delegate.getText() + "]"); break; case XMLStreamConstants.PROCESSING_INSTRUCTION: log.trace("PROCESSING_INSTRUCTION: "); log.trace(" [" + delegate.getPITarget() + "][" + delegate.getPIData() + "]"); break; case XMLStreamConstants.ENTITY_REFERENCE: log.trace("ENTITY_REFERENCE: "); log.trace(" " + delegate.getLocalName() + "[" + delegate.getText() + "]"); break; default: log.trace("UNKNOWN_STATE: " + currentEvent); } } } public DataHandler getDataHandler(String blobcid) { return delegate.getDataHandler(blobcid); } public boolean isInlineMTOM() { return delegate.isInlineMTOM(); } public void setInlineMTOM(boolean value) { delegate.setInlineMTOM(value); } }