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Apache CXF example source code file (ElementWriter.java)

This example Apache CXF source code file (ElementWriter.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Apache CXF tags/keywords

abstractmessagewriter, attributewriter, databindingexception, elementwriter, elementwriter, error, io, messagewriter, messagewriter, qname, string, string, xmlstreamexception, xmlstreamexception, xmlstreamwriter

The Apache CXF ElementWriter.java source code

/**
 * 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.cxf.aegis.xml.stax;

import java.io.OutputStream;

import javax.xml.namespace.QName;
import javax.xml.stream.XMLOutputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamWriter;

import org.apache.cxf.aegis.DatabindingException;
import org.apache.cxf.aegis.xml.AbstractMessageWriter;
import org.apache.cxf.aegis.xml.MessageWriter;
import org.apache.cxf.common.util.StringUtils;
import org.apache.cxf.staxutils.StaxUtils;

public class ElementWriter extends AbstractMessageWriter implements MessageWriter {
    private XMLStreamWriter writer;

    private String namespace;
    private String name;
    private String prefix;

    /**
     * Create an ElementWriter but without writing an element name.
     * 
     * @param writer
     */
    public ElementWriter(XMLStreamWriter writer) {
        this.writer = writer;
    }

    public ElementWriter(XMLStreamWriter writer, String name, String namespace) {
        this(writer, name, namespace, null);
    }

    public ElementWriter(XMLStreamWriter streamWriter, QName name) {
        this(streamWriter, name.getLocalPart(), name.getNamespaceURI());
    }

    public ElementWriter(XMLStreamWriter writer, String name, String namespace, String prefix) {
        this.writer = writer;
        this.namespace = namespace;
        this.name = name;
        this.prefix = prefix;

        try {
            writeStartElement();
        } catch (XMLStreamException e) {
            throw new DatabindingException("Error writing document.", e);
        }
    }

    /**
     * @param os
     * @throws XMLStreamException
     */
    public ElementWriter(OutputStream os, String name, String namespace) throws XMLStreamException {
        XMLOutputFactory ofactory = XMLOutputFactory.newInstance();
        this.writer = ofactory.createXMLStreamWriter(os);

        this.namespace = namespace;
        this.name = name;

        try {
            writeStartElement();
        } catch (XMLStreamException e) {
            throw new DatabindingException("Error writing document.", e);
        }
    }

    private void writeStartElement() throws XMLStreamException {
        if (!StringUtils.isEmpty(namespace)) {
            boolean declare = false;
            // Did the user declare a prefix?
            String decPrefix = writer.getNamespaceContext().getPrefix(namespace);

            // If the user didn't specify a prefix, create one
            if (StringUtils.isEmpty(prefix) 
                && decPrefix == null) {
               
                if (!StringUtils.isEmpty(namespace)) {
                    declare = true;
                    prefix = StaxUtils.getUniquePrefix(writer);
                } else {
                    prefix = "";
                    if (!StringUtils.isEmpty(writer.getNamespaceContext().getNamespaceURI(""))) {
                        declare = true;
                    }
                }
            } else if (StringUtils.isEmpty(prefix)) {
                prefix = decPrefix;
            } else if (!prefix.equals(decPrefix)) {
                declare = true;
            }

            writer.writeStartElement(prefix, name, namespace);

            if (declare) {
                writer.setPrefix(prefix, namespace);
                writer.writeNamespace(prefix, namespace);
            }
        } else {
            writer.writeStartElement(name);
        }
    }

    /**
     * @see org.apache.cxf.aegis.xml.MessageWriter#writeValue(java.lang.Object)
     */
    public void writeValue(Object value) {
        try {
            if (value != null) {
                writer.writeCharacters(value.toString());
            }
        } catch (XMLStreamException e) {
            throw new DatabindingException("Error writing document.", e);
        }
    }

    /**
     * @see org.apache.cxf.aegis.xml.MessageWriter#getWriter(java.lang.String)
     */
    public MessageWriter getElementWriter(String nm) {
        return new ElementWriter(writer, nm, namespace);
    }

    public MessageWriter getElementWriter(String nm, String ns) {
        return new ElementWriter(writer, nm, ns);
    }

    public MessageWriter getElementWriter(QName qname) {
        /*
         * No one really wants xmlns= in their XML, prefixes are preferred.
         * If the input qname has no prefix, go ahead and use the constructor that will
         * generate one.
         */
        if ("".equals(qname.getPrefix())) {
            return new ElementWriter(writer, qname.getLocalPart(), qname.getNamespaceURI());
        } else {
            return new ElementWriter(writer, qname.getLocalPart(), 
                                     qname.getNamespaceURI(), 
                                     qname.getPrefix());
        }
    }

    public String getNamespace() {
        return namespace;
    }

    public void close() {
        try {
            writer.writeEndElement();
            writer.flush();
        } catch (XMLStreamException e) {
            throw new DatabindingException("Error writing document.", e);
        }
    }

    public void flush() throws XMLStreamException {
        writer.flush();
    }

    public XMLStreamWriter getXMLStreamWriter() {
        return writer;
    }

    public MessageWriter getAttributeWriter(String nm) {
        return new AttributeWriter(writer, nm, namespace);
    }

    public MessageWriter getAttributeWriter(String nm, String ns) {
        return new AttributeWriter(writer, nm, ns);
    }

    public MessageWriter getAttributeWriter(QName qname) {
        return new AttributeWriter(writer, qname.getLocalPart(), qname.getNamespaceURI());
    }

    public String getPrefixForNamespace(String ns) {
        try {
            String pfx = writer.getPrefix(ns);

            if (pfx == null) {
                pfx = StaxUtils.getUniquePrefix(writer);

                writer.setPrefix(pfx, ns);
                writer.writeNamespace(pfx, ns);
            }

            return prefix;
        } catch (XMLStreamException e) {
            throw new DatabindingException("Error writing document.", e);
        }
    }

    public String getPrefixForNamespace(String ns, String hint) {
        try {
            String pfx = writer.getPrefix(ns);
            String contextPfx = writer.getNamespaceContext().getPrefix(ns);

            if (pfx == null) {
                String ns2 = writer.getNamespaceContext().getNamespaceURI(hint);
                // if the hint is "" (the default) and the context does 
                if (ns2 == null && !"".equals(hint)) { 
                    pfx = hint;
                } else if (ns.equals(ns2)) {
                    // just because it's in the context, doesn't mean it has been written.
                    pfx = hint;
                } else if (contextPfx != null) {
                    pfx = contextPfx;
                } else {
                    pfx = StaxUtils.getUniquePrefix(writer);
                }

                writer.setPrefix(pfx, ns);
                writer.writeNamespace(pfx, ns);
            }

            return pfx;
        } catch (XMLStreamException e) {
            throw new DatabindingException("Error writing document.", e);
        }
    }
}

Other Apache CXF examples (source code examples)

Here is a short list of links related to this Apache CXF ElementWriter.java source code file:

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