xmlserializer.java

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/*
 * Copyright 1999-2002,2004,2005 The Apache Software Foundation.
 * 
 * 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.
 */



// Sep 14, 2000:
//  Fixed problem with namespace handling. Contributed by
//  David Blondeau <[e-mail]>
// Sep 14, 2000:
//  Fixed serializer to report IO exception directly, instead at
//  the end of document processing.
//  Reported by Patrick Higgins <[e-mail]>
// Aug 21, 2000:
//  Fixed bug in startDocument not calling prepare.
//  Reported by Mikael Staldal <[e-mail]>
// Aug 21, 2000:
//  Added ability to omit DOCTYPE declaration.


package com.sun.org.apache.xml.internal.serialize;


import java.io.IOException;
import java.io.OutputStream;
import java.io.Writer;
import java.util.Enumeration;

import com.sun.org.apache.xerces.internal.dom.DOMMessageFormatter;
import com.sun.org.apache.xerces.internal.util.NamespaceSupport;
import com.sun.org.apache.xerces.internal.util.SymbolTable;
import com.sun.org.apache.xerces.internal.util.XMLChar;
import com.sun.org.apache.xerces.internal.util.XMLSymbols;
import com.sun.org.apache.xerces.internal.xni.NamespaceContext;
import org.w3c.dom.Attr;
import org.w3c.dom.DOMError;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.traversal.NodeFilter;
import org.xml.sax.AttributeList;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.AttributesImpl;

/**
 * Implements an XML serializer supporting both DOM and SAX pretty
 * serializing. For usage instructions see {@link Serializer}.
 * <p>
 * If an output stream is used, the encoding is taken from the
 * output format (defaults to <tt>UTF-8</tt>). If a writer is
 * used, make sure the writer uses the same encoding (if applies)
 * as specified in the output format.
 * <p>
 * The serializer supports both DOM and SAX. SAX serializing is done by firing
 * SAX events and using the serializer as a document handler. DOM serializing is done
 * by calling {@link #serialize(Document)} or by using DOM Level 3  
 * {@link org.w3c.dom.ls.DOMSerializer} and
 * serializing with {@link org.w3c.dom.ls.DOMSerializer#write},
 * {@link org.w3c.dom.ls.DOMSerializer#writeToString}.
 * <p>
 * If an I/O exception occurs while serializing, the serializer
 * will not throw an exception directly, but only throw it
 * at the end of serializing (either DOM or SAX's {@link
 * org.xml.sax.DocumentHandler#endDocument}.
 * <p>
 * For elements that are not specified as whitespace preserving,
 * the serializer will potentially break long text lines at space
 * boundaries, indent lines, and serialize elements on separate
 * lines. Line terminators will be regarded as spaces, and
 * spaces at beginning of line will be stripped.
 * @author <a href="mailto:[e-mail]">Assaf Arkin</a>
 * @author <a href="mailto:[e-mail]">Rahul Srivastava</a>
 * @author Elena Litani IBM
 * @version $Revision: 1.2.6.1 $ $Date: 2005/09/09 07:26:18 $
 * @see Serializer
 */
public class XMLSerializer
extends BaseMarkupSerializer {

    //
    // constants
    //

    protected static final boolean DEBUG = false;

    // 
    // data
    //

    // 
    // DOM Level 3 implementation: variables intialized in DOMSerializerImpl
    // 

    /** stores namespaces in scope */
    protected NamespaceSupport fNSBinder;

    /** stores all namespace bindings on the current element */
    protected NamespaceSupport fLocalNSBinder;

    /** symbol table for serialization */
    protected SymbolTable fSymbolTable;    

    protected final static String PREFIX = "NS";

    /**
     * Controls whether namespace fixup should be performed during
     * the serialization. 
     * NOTE: if this field is set to true the following 
     * fields need to be initialized: fNSBinder, fLocalNSBinder, fSymbolTable, 
     * XMLSymbols.EMPTY_STRING, fXmlSymbol, fXmlnsSymbol
     */
    protected boolean fNamespaces = false;

    /**
     * Controls whether namespace prefixes will be printed out during serialization
     */
    protected boolean fNamespacePrefixes = true;
	

    private boolean fPreserveSpace;


    /**
     * Constructs a new serializer. The serializer cannot be used without
     * calling {@link #setOutputCharStream} or {@link #setOutputByteStream}
     * first.
     */
    public XMLSerializer() {
        super( new OutputFormat( Method.XML, null, false ) );
    }


    /**
     * Constructs a new serializer. The serializer cannot be used without
     * calling {@link #setOutputCharStream} or {@link #setOutputByteStream}
     * first.
     */
    public XMLSerializer( OutputFormat format ) {
        super( format != null ? format : new OutputFormat( Method.XML, null, false ) );
        _format.setMethod( Method.XML );
    }


    /**
     * Constructs a new serializer that writes to the specified writer
     * using the specified output format. If <tt>format</tt> is null,
     * will use a default output format.
     *
     * @param writer The writer to use
     * @param format The output format to use, null for the default
     */
    public XMLSerializer( Writer writer, OutputFormat format ) {
        super( format != null ? format : new OutputFormat( Method.XML, null, false ) );
        _format.setMethod( Method.XML );
        setOutputCharStream( writer );
    }


    /**
     * Constructs a new serializer that writes to the specified output
     * stream using the specified output format. If <tt>format</tt>
     * is null, will use a default output format.
     *
     * @param output The output stream to use
     * @param format The output format to use, null for the default
     */
    public XMLSerializer( OutputStream output, OutputFormat format ) {
        super( format != null ? format : new OutputFormat( Method.XML, null, false ) );
        _format.setMethod( Method.XML );
        setOutputByteStream( output );
    }


    public void setOutputFormat( OutputFormat format ) {
        super.setOutputFormat( format != null ? format : new OutputFormat( Method.XML, null, false ) );
    }


    /**
     * This methods turns on namespace fixup algorithm during
     * DOM serialization.
     * @see org.w3c.dom.ls.DOMSerializer
     * 
     * @param namespaces
     */
    public void setNamespaces (boolean namespaces){
        fNamespaces = namespaces;
        if (fNSBinder == null) {
            fNSBinder = new NamespaceSupport();
            fLocalNSBinder = new NamespaceSupport();
            fSymbolTable = new SymbolTable();
        }
    }

    //-----------------------------------------//
    // SAX content handler serializing methods //
    //-----------------------------------------//


    public void startElement( String namespaceURI, String localName,
                              String rawName, Attributes attrs )
    throws SAXException
    {
        int          i;
        boolean      preserveSpace;
        ElementState state;
        String       name;
        String       value;
        boolean      addNSAttr = false;

        if (DEBUG) {
            System.out.println("==>startElement("+namespaceURI+","+localName+
                               ","+rawName+")");
        }

        try {
            if (_printer == null) {
                String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.SERIALIZER_DOMAIN, "NoWriterSupplied", null);
                throw new IllegalStateException(msg);
            }

            state = getElementState();
            if (isDocumentState()) {
                // If this is the root element handle it differently.
                // If the first root element in the document, serialize
                // the document's DOCTYPE. Space preserving defaults
                // to that of the output format.
                if (! _started)
                    startDocument( ( localName == null || localName.length() == 0 ) ? rawName : localName );
            } else {
                // For any other element, if first in parent, then
                // close parent's opening tag and use the parnet's
                // space preserving.
                if (state.empty)
                    _printer.printText( '>' );
                // Must leave CData section first
                if (state.inCData) {
                    _printer.printText( "]]>" );
                    state.inCData = false;
                }
                // Indent this element on a new line if the first
                // content of the parent element or immediately
                // following an element or a comment
                if (_indenting && ! state.preserveSpace &&
                    ( state.empty || state.afterElement || state.afterComment))
                    _printer.breakLine();
            }
            preserveSpace = state.preserveSpace;

            //We remove the namespaces from the attributes list so that they will
            //be in _prefixes
            attrs = extractNamespaces(attrs);

            // Do not change the current element state yet.
            // This only happens in endElement().
            if (rawName == null || rawName.length() == 0) {
                if (localName == null) {
                    String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.SERIALIZER_DOMAIN, "NoName", null);
                    throw new SAXException(msg);
                }
                if (namespaceURI != null && ! namespaceURI.equals( "" )) {
                    String prefix;
                    prefix = getPrefix( namespaceURI );
                    if (prefix != null && prefix.length() > 0)
                        rawName = prefix + ":" + localName;
                    else
                        rawName = localName;
                } else
                    rawName = localName;
                addNSAttr = true;
            }

            _printer.printText( '<' );
            _printer.printText( rawName );
            _printer.indent();

            // For each attribute print it's name and value as one part,
            // separated with a space so the element can be broken on
            // multiple lines.
            if (attrs != null) {
                for (i = 0 ; i < attrs.getLength() ; ++i) {
                    _printer.printSpace();

                    name = attrs.getQName( i );
                    if (name != null && name.length() == 0) {
                        String prefix;
                        String attrURI;

                        name = attrs.getLocalName( i );
                        attrURI = attrs.getURI( i );
                        if (( attrURI != null && attrURI.length() != 0 ) &&
                            ( namespaceURI == null || namespaceURI.length() == 0 ||
                              ! attrURI.equals( namespaceURI ) )) {
                            prefix = getPrefix( attrURI );
                            if (prefix != null && prefix.length() > 0)
                                name = prefix + ":" + name;
                        }
                    }

                    value = attrs.getValue( i );
                    if (value == null)
                        value = "";
                    _printer.printText( name );
                    _printer.printText( "=\"" );
                    printEscaped( value );
                    _printer.printText( '"' );

                    // If the attribute xml:space exists, determine whether
                    // to preserve spaces in this and child nodes based on
                    // its value.
                    if (name.equals( "xml:space" )) {
                        if (value.equals( "preserve" ))
                            preserveSpace = true;
                        else
                            preserveSpace = _format.getPreserveSpace();
                    }
                }
            }

            if (_prefixes != null) {
                Enumeration keys;

                keys = _prefixes.keys();
                while (keys.hasMoreElements()) {
                    _printer.printSpace();
                    value = (String) keys.nextElement();
                    name = (String) _prefixes.get( value );
                    if (name.length() == 0) {
                        _printer.printText( "xmlns=\"" );
                        printEscaped( value );
                        _printer.printText( '"' );
                    } else {
                        _printer.printText( "xmlns:" );
                        _printer.printText( name );
                        _printer.printText( "=\"" );
                        printEscaped( value );
                        _printer.printText( '"' );
                    }
                }
            }

            // Now it's time to enter a new element state
            // with the tag name and space preserving.
            // We still do not change the curent element state.
            state = enterElementState( namespaceURI, localName, rawName, preserveSpace );
            name = ( localName == null || localName.length() == 0 ) ? rawName : namespaceURI + "^" + localName;
            state.doCData = _format.isCDataElement( name );
            state.unescaped = _format.isNonEscapingElement( name );
        } catch (IOException except) {
            throw new SAXException( except );
        }
    }


    public void endElement( String namespaceURI, String localName,