XMLEventStreamReader.java

/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed 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 com.xiongyingqi.util.xml;

import javax.xml.namespace.NamespaceContext;
import javax.xml.namespace.QName;
import javax.xml.stream.Location;
import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.events.*;
import java.util.Iterator;

/**
 * Implementation of the {@link javax.xml.stream.XMLStreamReader} interface that wraps a {@link javax.xml.stream.XMLEventReader}. Useful,
 * because the StAX {@link javax.xml.stream.XMLInputFactory} allows one to create a event reader from a stream reader,
 * but not vice-versa.
 *
 * @author Arjen Poutsma
 * @see org.springframework.util.xml.StaxUtils#createEventStreamReader(javax.xml.stream.XMLEventReader)
 * @since 3.0
 */
@SuppressWarnings("rawtypes")
class XMLEventStreamReader extends AbstractXMLStreamReader {

    private XMLEvent event;

    private final XMLEventReader eventReader;

    XMLEventStreamReader(XMLEventReader eventReader) throws XMLStreamException {
        this.eventReader = eventReader;
        event = eventReader.nextEvent();
    }

    @Override
    public boolean isStandalone() {
        if (event.isStartDocument()) {
            return ((StartDocument) event).isStandalone();
        } else {
            throw new IllegalStateException();
        }
    }

    @Override
    public String getVersion() {
        if (event.isStartDocument()) {
            return ((StartDocument) event).getVersion();
        } else {
            return null;
        }
    }

    @Override
    public int getTextStart() {
        return 0;
    }

    @Override
    public String getText() {
        if (event.isCharacters()) {
            return event.asCharacters().getData();
        } else if (event.getEventType() == XMLEvent.COMMENT) {
            return ((Comment) event).getText();
        } else {
            throw new IllegalStateException();
        }
    }

    @Override
    public String getPITarget() {
        if (event.isProcessingInstruction()) {
            return ((ProcessingInstruction) event).getTarget();
        } else {
            throw new IllegalStateException();
        }
    }

    @Override
    public String getPIData() {
        if (event.isProcessingInstruction()) {
            return ((ProcessingInstruction) event).getData();
        } else {
            throw new IllegalStateException();
        }
    }

    @Override
    public int getNamespaceCount() {
        Iterator namespaces;
        if (event.isStartElement()) {
            namespaces = event.asStartElement().getNamespaces();
        } else if (event.isEndElement()) {
            namespaces = event.asEndElement().getNamespaces();
        } else {
            throw new IllegalStateException();
        }
        return countIterator(namespaces);
    }

    @Override
    public NamespaceContext getNamespaceContext() {
        if (event.isStartElement()) {
            return event.asStartElement().getNamespaceContext();
        } else {
            throw new IllegalStateException();
        }
    }

    @Override
    public QName getName() {
        if (event.isStartElement()) {
            return event.asStartElement().getName();
        } else if (event.isEndElement()) {
            return event.asEndElement().getName();
        } else {
            throw new IllegalStateException();
        }
    }

    @Override
    public Location getLocation() {
        return event.getLocation();
    }

    @Override
    public int getEventType() {
        return event.getEventType();
    }

    @Override
    public String getEncoding() {
        return null;
    }

    @Override
    public String getCharacterEncodingScheme() {
        return null;
    }

    @Override
    public int getAttributeCount() {
        if (!event.isStartElement()) {
            throw new IllegalStateException();
        }
        Iterator attributes = event.asStartElement().getAttributes();
        return countIterator(attributes);
    }

    @Override
    public void close() throws XMLStreamException {
        eventReader.close();
    }

    @Override
    public QName getAttributeName(int index) {
        return getAttribute(index).getName();
    }

    @Override
    public String getAttributeType(int index) {
        return getAttribute(index).getDTDType();
    }

    @Override
    public String getAttributeValue(int index) {
        return getAttribute(index).getValue();
    }

    @Override
    public String getNamespacePrefix(int index) {
        return getNamespace(index).getPrefix();
    }

    @Override
    public String getNamespaceURI(int index) {
        return getNamespace(index).getNamespaceURI();
    }

    @Override
    public Object getProperty(String name) throws IllegalArgumentException {
        return eventReader.getProperty(name);
    }

    @Override
    public boolean isAttributeSpecified(int index) {
        return getAttribute(index).isSpecified();
    }

    @Override
    public int next() throws XMLStreamException {
        event = eventReader.nextEvent();
        return event.getEventType();
    }

    @Override
    public boolean standaloneSet() {
        if (event.isStartDocument()) {
            return ((StartDocument) event).standaloneSet();
        } else {
            throw new IllegalStateException();
        }
    }

    private int countIterator(Iterator iterator) {
        int count = 0;
        while (iterator.hasNext()) {
            iterator.next();
            count++;
        }
        return count;
    }

    private Attribute getAttribute(int index) {
        if (!event.isStartElement()) {
            throw new IllegalStateException();
        }
        int count = 0;
        Iterator attributes = event.asStartElement().getAttributes();
        while (attributes.hasNext()) {
            Attribute attribute = (Attribute) attributes.next();
            if (count == index) {
                return attribute;
            } else {
                count++;
            }
        }
        throw new IllegalArgumentException();
    }

    private Namespace getNamespace(int index) {
        Iterator namespaces;
        if (event.isStartElement()) {
            namespaces = event.asStartElement().getNamespaces();
        } else if (event.isEndElement()) {
            namespaces = event.asEndElement().getNamespaces();
        } else {
            throw new IllegalStateException();
        }
        int count = 0;
        while (namespaces.hasNext()) {
            Namespace namespace = (Namespace) namespaces.next();
            if (count == index) {
                return namespace;
            } else {
                count++;
            }
        }
        throw new IllegalArgumentException();
    }
}