net.sf.jsefa.xml.lowlevel.StaxBasedXmlLowLevelDeserializer Maven / Gradle / Ivy

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JSefa (Java Simple exchange format api) is a simple library for stream-based serialization of java objects to XML, CSV, FLR or any other format and back again using an iterator-style interface independent of the serialization format. The mapping between java object types and types of the serialization format (e. g. xml complex element types) can be defined either by annotating the java classes or programmatically using a simple API. The current implementation supports XML, CSV and FLR - for XML it is based on JSR 173.
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/*
 * Copyright 2007 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 net.sf.jsefa.xml.lowlevel;

import static javax.xml.stream.XMLStreamConstants.CDATA;
import static javax.xml.stream.XMLStreamConstants.CHARACTERS;
import static javax.xml.stream.XMLStreamConstants.END_ELEMENT;
import static javax.xml.stream.XMLStreamConstants.START_ELEMENT;

import java.io.BufferedReader;
import java.io.Reader;

import javax.xml.stream.Location;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;

import net.sf.jsefa.common.lowlevel.InputPosition;
import net.sf.jsefa.common.lowlevel.LowLevelDeserializationException;
import net.sf.jsefa.xml.lowlevel.config.XmlLowLevelConfiguration;
import net.sf.jsefa.xml.lowlevel.model.Attribute;
import net.sf.jsefa.xml.lowlevel.model.AttributeImpl;
import net.sf.jsefa.xml.lowlevel.model.ElementEndImpl;
import net.sf.jsefa.xml.lowlevel.model.ElementStartImpl;
import net.sf.jsefa.xml.lowlevel.model.TextContentImpl;
import net.sf.jsefa.xml.lowlevel.model.XmlItem;
import net.sf.jsefa.xml.lowlevel.model.XmlItemType;
import net.sf.jsefa.xml.namespace.NamespaceConstants;
import net.sf.jsefa.xml.namespace.QName;

/**
 * Stax based implementation of {@link XmlLowLevelDeserializer}.
 * 
 * @author Norman Lahme-Huetig
 * 
 */

public final class StaxBasedXmlLowLevelDeserializer implements XmlLowLevelDeserializer {
    private final XmlLowLevelConfiguration config;

    private Reader reader;

    private XMLStreamReader streamReader;

    private int depth = -1;

    private XmlItemType currentItemType;

    private XmlItem currentItem;

    private boolean eventPrefetched;

    private boolean decreaseDepthOnNextEvent;

    /**
     * Constructs a new StaxBasedXmlLowLevelDeserializer.
     * 
     * @param config the configuration object
     */
    public StaxBasedXmlLowLevelDeserializer(XmlLowLevelConfiguration config) {
        this.config = config;
    }

    /**
     * {@inheritDoc}
     */
    public void open(Reader reader) {
        open(reader, null);
    }

    /**
     * {@inheritDoc}
     */
    public void open(Reader reader, String systemId) {
        if (reader instanceof BufferedReader) {
            this.reader = (BufferedReader) reader;
        } else {
            this.reader = new BufferedReader(reader);
        }
        XMLInputFactory factory = XMLInputFactory.newInstance();
        try {
            if (systemId != null) {
                this.streamReader = factory.createXMLStreamReader(systemId, this.reader);
            } else {
                this.streamReader = factory.createXMLStreamReader(this.reader);
            }
        } catch (XMLStreamException e) {
            throw new LowLevelDeserializationException("Error while opening the deserialization stream", e);
        }
        this.depth = -1;
        this.currentItem = null;
        this.currentItemType = XmlItemType.NONE;
        this.eventPrefetched = false;
        this.decreaseDepthOnNextEvent = false;
    }

    /**
     * {@inheritDoc}
     */
    public boolean hasNext() {
        try {
            return this.eventPrefetched || this.streamReader.hasNext();
        } catch (XMLStreamException e) {
            throw new LowLevelDeserializationException(e);
        }
    }

    /**
     * {@inheritDoc}
     */
    public void moveToNext() {
        if (this.decreaseDepthOnNextEvent) {
            this.depth--;
            this.decreaseDepthOnNextEvent = false;
        }
        if (!this.eventPrefetched && !hasNext()) {
            this.currentItemType = XmlItemType.NONE;
            this.currentItem = null;
            return;
        }
        try {
            int event;
            if (this.eventPrefetched) {
                event = this.streamReader.getEventType();
                this.eventPrefetched = false;
            } else {
                event = this.streamReader.next();
            }
            switch (event) {
            case START_ELEMENT:
                this.depth++;
                this.currentItemType = XmlItemType.ELEMENT_START;
                break;
            case END_ELEMENT:
                this.currentItemType = XmlItemType.ELEMENT_END;
                this.decreaseDepthOnNextEvent = true;
                break;
            case CDATA:
                this.currentItemType = XmlItemType.TEXT_CONTENT;
                break;
            case CHARACTERS:
                this.currentItemType = XmlItemType.TEXT_CONTENT;
                break;
            default:
                this.currentItemType = XmlItemType.UNKNOWN;
            }
            this.currentItem = null;
        } catch (XMLStreamException e) {
            throw new LowLevelDeserializationException(e);
        }
    }

    /**
     * {@inheritDoc}
     */
    public XmlItemType currentType() {
        return this.currentItemType;
    }

    /**
     * {@inheritDoc}
     */
    public XmlItem current() {
        if (this.currentItem == null) {
            if (this.currentItemType == XmlItemType.ELEMENT_START) {
                QName name = getElementName();
                QName dataTypeName = getDataTypeName();
                Attribute[] attributes = getAttributes();
                this.currentItem = new ElementStartImpl(name, dataTypeName, attributes, this.depth);
            } else if (this.currentItemType == XmlItemType.ELEMENT_END) {
                QName name = getElementName();
                this.currentItem = new ElementEndImpl(name, this.depth);
            } else if (this.currentItemType == XmlItemType.TEXT_CONTENT) {
                try {
                    if (!this.streamReader.hasNext()) {
                        this.currentItem = new TextContentImpl(this.streamReader.getText());
                    } else {
                        String text = this.streamReader.getText();
                        int event = this.streamReader.next();
                        this.eventPrefetched = true;
                        if ((event != CDATA) && (event != CHARACTERS)) {
                            this.currentItem = new TextContentImpl(text);
                        } else {
                            StringBuilder buffer = new StringBuilder(text);
                            do {
                                buffer.append(this.streamReader.getText());
                                event = this.streamReader.next();
                                if ((event != CDATA) && (event != CHARACTERS)) {
                                    break;
                                }
                            } while (this.streamReader.hasNext());
                            this.currentItem = new TextContentImpl(buffer.toString());
                        }
                    }
                } catch (XMLStreamException e) {
                    throw new LowLevelDeserializationException(e);
                }

            }

        }
        return this.currentItem;
    }

    /**
     * {@inheritDoc}
     */
    public int currentDepth() {
        return this.depth;
    }

    /**
     * {@inheritDoc}
     */
    public void close(boolean closeReader) {
        try {
            this.streamReader.close();
            if (closeReader) {
                this.reader.close();
            }
        } catch (Exception e) {
            throw new LowLevelDeserializationException("Error while closing the deserialization stream", e);
        }
        this.reader = null;
    }

    /**
     * {@inheritDoc}
     */
    public InputPosition getInputPosition() {
        if (this.reader != null) {
            try {
                Location location = this.streamReader.getLocation();
                if (location != null && location.getLineNumber() >= 0 && location.getColumnNumber() >= 0) {
                    return new InputPosition(location.getLineNumber(), location.getColumnNumber());
                }
            } catch (Exception e) {
                return null;
            }
        }
        return null;
    }

    private QName getElementName() {
        return QName.create(normalizeURI(this.streamReader.getNamespaceURI()), this.streamReader.getLocalName());
    }

    private QName getDataTypeName() {
        QName dataTypeName = null;
        String dataTypeNameStr = this.streamReader.getAttributeValue(this.config.getDataTypeAttributeName()
                .getUri(), this.config.getDataTypeAttributeName().getLocalName());
        if (dataTypeNameStr != null) {
            int delimiterPos = dataTypeNameStr.indexOf(":");
            if (delimiterPos == -1) {
                dataTypeName = QName.create(normalizeURI(this.streamReader.getNamespaceURI("")), dataTypeNameStr);
            } else {
                String prefix = dataTypeNameStr.substring(0, delimiterPos);
                String uri = this.streamReader.getNamespaceURI(prefix);
                String localName = "";
                if (delimiterPos < dataTypeNameStr.length() - 1) {
                    localName = dataTypeNameStr.substring(delimiterPos + 1);
                }
                dataTypeName = QName.create(normalizeURI(uri), localName);
            }
        }
        return dataTypeName;
    }

    private Attribute[] getAttributes() {
        int attributeCount = this.streamReader.getAttributeCount();
        Attribute[] attributes = new Attribute[attributeCount];
        for (int i = 0; i < attributeCount; i++) {
            QName name = QName.create(normalizeURI(this.streamReader.getAttributeNamespace(i)), this.streamReader
                    .getAttributeLocalName(i));
            String value = this.streamReader.getAttributeValue(i);
            attributes[i] = new AttributeImpl(name, value);
        }
        return attributes;
    }

    private String normalizeURI(String uri) {
        if (uri != null) {
            return uri;
        } else {
            return NamespaceConstants.NO_NAMESPACE_URI;
        }
    }

}