Filter to write an XML document from a SAX event stream
//XMLWriter.java - serialize an XML document.
//Written by David Megginson, david@megginson.com
//NO WARRANTY! This class is in the public domain.
//Modified by John Cowan and Leigh Klotz for the TagSoup project. Still in the public domain.
//New features:
// it is a LexicalHandler
// it prints a comment if the LexicalHandler#comment method is called
// it supports certain XSLT output properties using get/setOutputProperty
//$Id: XMLWriter.java,v 1.1 2004/01/28 05:35:43 joe Exp $
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Properties;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.AttributesImpl;
import org.xml.sax.helpers.NamespaceSupport;
import org.xml.sax.helpers.XMLFilterImpl;
import org.xml.sax.ext.LexicalHandler;
/**
* Filter to write an XML document from a SAX event stream.
*
* <p>
* This class can be used by itself or as part of a SAX event stream: it takes
* as input a series of SAX2 ContentHandler events and uses the information in
* those events to write an XML document. Since this class is a filter, it can
* also pass the events on down a filter chain for further processing (you can
* use the XMLWriter to take a snapshot of the current state at any point in a
* filter chain), and it can be used directly as a ContentHandler for a SAX2
* XMLReader.
* </p>
*
* <p>
* The client creates a document by invoking the methods for standard SAX2
* events, always beginning with the {@link #startDocument startDocument} method
* and ending with the {@link #endDocument endDocument} method. There are
* convenience methods provided so that clients to not have to create empty
* attribute lists or provide empty strings as parameters; for example, the
* method invocation
* </p>
*
* <pre>
* w.startElement("foo");
* </pre>
*
* <p>
* is equivalent to the regular SAX2 ContentHandler method
* </p>
*
* <pre>
* w.startElement("", "foo", "", new AttributesImpl());
* </pre>
*
* <p>
* Except that it is more efficient because it does not allocate a new empty
* attribute list each time. The following code will send a simple XML document
* to standard output:
* </p>
*
* <pre>
* XMLWriter w = new XMLWriter();
*
* w.startDocument();
* w.startElement("greeting");
* w.characters("Hello, world!");
* w.endElement("greeting");
* w.endDocument();
* </pre>
*
* <p>
* The resulting document will look like this:
* </p>
*
* <pre>
* <?xml version="1.0" standalone="yes"?>
*
* <greeting>Hello, world!</greeting>
* </pre>
*
* <p>
* In fact, there is an even simpler convenience method, <var>dataElement</var>,
* designed for writing elements that contain only character data, so the code
* to generate the document could be shortened to
* </p>
*
* <pre>
* XMLWriter w = new XMLWriter();
*
* w.startDocument();
* w.dataElement("greeting", "Hello, world!");
* w.endDocument();
* </pre>
*
* <h2>Whitespace</h2>
*
* <p>
* According to the XML Recommendation, <em>all</em> whitespace in an XML
* document is potentially significant to an application, so this class never
* adds newlines or indentation. If you insert three elements in a row, as in
* </p>
*
* <pre>
* w.dataElement("item", "1");
* w.dataElement("item", "2");
* w.dataElement("item", "3");
* </pre>
*
* <p>
* you will end up with
* </p>
*
* <pre>
* <item>1</item><item>3</item><item>3</item>
* </pre>
*
* <p>
* You need to invoke one of the <var>characters</var> methods explicitly to
* add newlines or indentation. Alternatively, you can use
* {@link com.megginson.sax.DataWriter DataWriter}, which is derived from this
* class -- it is optimized for writing purely data-oriented (or field-oriented)
* XML, and does automatic linebreaks and indentation (but does not support
* mixed content properly).
* </p>
*
*
* <h2>Namespace Support</h2>
*
* <p>
* The writer contains extensive support for XML Namespaces, so that a client
* application does not have to keep track of prefixes and supply <var>xmlns</var>
* attributes. By default, the XML writer will generate Namespace declarations
* in the form _NS1, _NS2, etc., wherever they are needed, as in the following
* example:
* </p>
*
* <pre>
* w.startDocument();
* w.emptyElement("http://www.foo.com/ns/", "foo");
* w.endDocument();
* </pre>
*
* <p>
* The resulting document will look like this:
* </p>
*
* <pre>
* <?xml version="1.0" standalone="yes"?>
*
* <_NS1:foo xmlns:_NS1="http://www.foo.com/ns/"/>
* </pre>
*
* <p>
* In many cases, document authors will prefer to choose their own prefixes
* rather than using the (ugly) default names. The XML writer allows two methods
* for selecting prefixes:
* </p>
*
* <ol>
* <li>the qualified name</li>
* <li>the {@link #setPrefix setPrefix} method.</li>
* </ol>
*
* <p>
* Whenever the XML writer finds a new Namespace URI, it checks to see if a
* qualified (prefixed) name is also available; if so it attempts to use the
* name's prefix (as long as the prefix is not already in use for another
* Namespace URI).
* </p>
*
* <p>
* Before writing a document, the client can also pre-map a prefix to a
* Namespace URI with the setPrefix method:
* </p>
*
* <pre>
* w.setPrefix("http://www.foo.com/ns/", "foo");
* w.startDocument();
* w.emptyElement("http://www.foo.com/ns/", "foo");
* w.endDocument();
* </pre>
*
* <p>
* The resulting document will look like this:
* </p>
*
* <pre>
* <?xml version="1.0" standalone="yes"?>
*
* <foo:foo xmlns:foo="http://www.foo.com/ns/"/>
* </pre>
*
* <p>
* The default Namespace simply uses an empty string as the prefix:
* </p>
*
* <pre>
* w.setPrefix("http://www.foo.com/ns/", "");
* w.startDocument();
* w.emptyElement("http://www.foo.com/ns/", "foo");
* w.endDocument();
* </pre>
*
* <p>
* The resulting document will look like this:
* </p>
*
* <pre>
* <?xml version="1.0" standalone="yes"?>
*
* <foo xmlns="http://www.foo.com/ns/"/>
* </pre>
*
* <p>
* By default, the XML writer will not declare a Namespace until it is actually
* used. Sometimes, this approach will create a large number of Namespace
* declarations, as in the following example:
* </p>
*
* <pre>
* <xml version="1.0" standalone="yes"?>
*
* <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
* <rdf:Description about="http://www.foo.com/ids/books/12345">
* <dc:title xmlns:dc="http://www.purl.org/dc/">A Dark Night</dc:title>
* <dc:creator xmlns:dc="http://www.purl.org/dc/">Jane Smith</dc:title>
* <dc:date xmlns:dc="http://www.purl.org/dc/">2000-09-09</dc:title>
* </rdf:Description>
* </rdf:RDF>
* </pre>
*
* <p>
* The "rdf" prefix is declared only once, because the RDF Namespace is used by
* the root element and can be inherited by all of its descendants; the "dc"
* prefix, on the other hand, is declared three times, because no higher element
* uses the Namespace. To solve this problem, you can instruct the XML writer to
* predeclare Namespaces on the root element even if they are not used there:
* </p>
*
* <pre>
* w.forceNSDecl("http://www.purl.org/dc/");
* </pre>
*
* <p>
* Now, the "dc" prefix will be declared on the root element even though it's
* not needed there, and can be inherited by its descendants:
* </p>
*
* <pre>
* <xml version="1.0" standalone="yes"?>
*
* <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
* xmlns:dc="http://www.purl.org/dc/">
* <rdf:Description about="http://www.foo.com/ids/books/12345">
* <dc:title>A Dark Night</dc:title>
* <dc:creator>Jane Smith</dc:title>
* <dc:date>2000-09-09</dc:title>
* </rdf:Description>
* </rdf:RDF>
* </pre>
*
* <p>
* This approach is also useful for declaring Namespace prefixes that be used by
* qualified names appearing in attribute values or character data.
* </p>
*
* @author David Megginson, david@megginson.com
* @version 0.2
* @see org.xml.sax.XMLFilter
* @see org.xml.sax.ContentHandler
*/
public class XMLWriter extends XMLFilterImpl implements LexicalHandler {
// //////////////////////////////////////////////////////////////////
// Constructors.
// //////////////////////////////////////////////////////////////////
/**
* Create a new XML writer.
*
* <p>
* Write to standard output.
* </p>
*/
public XMLWriter() {
init(null);
}
/**
* Create a new XML writer.
*
* <p>
* Write to the writer provided.
* </p>
*
* @param writer
* The output destination, or null to use standard output.
*/
public XMLWriter(Writer writer) {
init(writer);
}
/**
* Create a new XML writer.
*
* <p>
* Use the specified XML reader as the parent.
* </p>
*
* @param xmlreader
* The parent in the filter chain, or null for no parent.
*/
public XMLWriter(XMLReader xmlreader) {
super(xmlreader);
init(null);
}
/**
* Create a new XML writer.
*
* <p>
* Use the specified XML reader as the parent, and write to the specified
* writer.
* </p>
*
* @param xmlreader
* The parent in the filter chain, or null for no parent.
* @param writer
* The output destination, or null to use standard output.
*/
public XMLWriter(XMLReader xmlreader, Writer writer) {
super(xmlreader);
init(writer);
}
/**
* Internal initialization method.
*
* <p>
* All of the public constructors invoke this method.
*
* @param writer
* The output destination, or null to use standard output.
*/
private void init(Writer writer) {
setOutput(writer);
nsSupport = new NamespaceSupport();
prefixTable = new Hashtable();
forcedDeclTable = new Hashtable();
doneDeclTable = new Hashtable();
outputProperties = new Properties();
}
// //////////////////////////////////////////////////////////////////
// Public methods.
// //////////////////////////////////////////////////////////////////
/**
* Reset the writer.
*
* <p>
* This method is especially useful if the writer throws an exception before
* it is finished, and you want to reuse the writer for a new document. It
* is usually a good idea to invoke {@link #flush flush} before resetting
* the writer, to make sure that no output is lost.
* </p>
*
* <p>
* This method is invoked automatically by the
* {@link #startDocument startDocument} method before writing a new
* document.
* </p>
*
* <p>
* <strong>Note:</strong> this method will <em>not</em> clear the prefix
* or URI information in the writer or the selected output writer.
* </p>
*
* @see #flush
*/
public void reset() {
elementLevel = 0;
prefixCounter = 0;
nsSupport.reset();
}
/**
* Flush the output.
*
* <p>
* This method flushes the output stream. It is especially useful when you
* need to make certain that the entire document has been written to output
* but do not want to close the output stream.
* </p>
*
* <p>
* This method is invoked automatically by the
* {@link #endDocument endDocument} method after writing a document.
* </p>
*
* @see #reset
*/
public void flush() throws IOException {
output.flush();
}
/**
* Set a new output destination for the document.
*
* @param writer
* The output destination, or null to use standard output.
* @return The current output writer.
* @see #flush
*/
public void setOutput(Writer writer) {
if (writer == null) {
output = new OutputStreamWriter(System.out);
} else {
output = writer;
}
}
/**
* Specify a preferred prefix for a Namespace URI.
*
* <p>
* Note that this method does not actually force the Namespace to be
* declared; to do that, use the {@link #forceNSDecl(java.lang.String)
* forceNSDecl} method as well.
* </p>
*
* @param uri
* The Namespace URI.
* @param prefix
* The preferred prefix, or "" to select the default Namespace.
* @see #getPrefix
* @see #forceNSDecl(java.lang.String)
* @see #forceNSDecl(java.lang.String,java.lang.String)
*/
public void setPrefix(String uri, String prefix) {
prefixTable.put(uri, prefix);
}
/**
* Get the current or preferred prefix for a Namespace URI.
*
* @param uri
* The Namespace URI.
* @return The preferred prefix, or "" for the default Namespace.
* @see #setPrefix
*/
public String getPrefix(String uri) {
return (String) prefixTable.get(uri);
}
/**
* Force a Namespace to be declared on the root element.
*
* <p>
* By default, the XMLWriter will declare only the Namespaces needed for an
* element; as a result, a Namespace may be declared many places in a
* document if it is not used on the root element.
* </p>
*
* <p>
* This method forces a Namespace to be declared on the root element even if
* it is not used there, and reduces the number of xmlns attributes in the
* document.
* </p>
*
* @param uri
* The Namespace URI to declare.
* @see #forceNSDecl(java.lang.String,java.lang.String)
* @see #setPrefix
*/
public void forceNSDecl(String uri) {
forcedDeclTable.put(uri, Boolean.TRUE);
}
/**
* Force a Namespace declaration with a preferred prefix.
*
* <p>
* This is a convenience method that invokes {@link #setPrefix setPrefix}
* then {@link #forceNSDecl(java.lang.String) forceNSDecl}.
* </p>
*
* @param uri
* The Namespace URI to declare on the root element.
* @param prefix
* The preferred prefix for the Namespace, or "" for the default
* Namespace.
* @see #setPrefix
* @see #forceNSDecl(java.lang.String)
*/
public void forceNSDecl(String uri, String prefix) {
setPrefix(uri, prefix);
forceNSDecl(uri);
}
// //////////////////////////////////////////////////////////////////
// Methods from org.xml.sax.ContentHandler.
// //////////////////////////////////////////////////////////////////
/**
* Write the XML declaration at the beginning of the document.
*
* Pass the event on down the filter chain for further processing.
*
* @exception org.xml.sax.SAXException
* If there is an error writing the XML declaration, or if a
* handler further down the filter chain raises an exception.
* @see org.xml.sax.ContentHandler#startDocument
*/
public void startDocument() throws SAXException {
reset();
if (!("yes".equals(outputProperties.getProperty(OMIT_XML_DECLARATION,
"no"))))
write("<?xml version=\"1.0\" standalone=\"yes\"?>\n\n");
super.startDocument();
}
/**
* Write a newline at the end of the document.
*
* Pass the event on down the filter chain for further processing.
*
* @exception org.xml.sax.SAXException
* If there is an error writing the newline, or if a handler
* further down the filter chain raises an exception.
* @see org.xml.sax.ContentHandler#endDocument
*/
public void endDocument() throws SAXException {
write('\n');
super.endDocument();
try {
flush();
} catch (IOException e) {
throw new SAXException(e);
}
}
/**
* Write a start tag.
*
* Pass the event on down the filter chain for further processing.
*
* @param uri
* The Namespace URI, or the empty string if none is available.
* @param localName
* The element's local (unprefixed) name (required).
* @param qName
* The element's qualified (prefixed) name, or the empty string
* is none is available. This method will use the qName as a
* template for generating a prefix if necessary, but it is not
* guaranteed to use the same qName.
* @param atts
* The element's attribute list (must not be null).
* @exception org.xml.sax.SAXException
* If there is an error writing the start tag, or if a
* handler further down the filter chain raises an exception.
* @see org.xml.sax.ContentHandler#startElement
*/
public void startElement(String uri, String localName, String qName,
Attributes atts) throws SAXException {
elementLevel++;
nsSupport.pushContext();
write('<');
writeName(uri, localName, qName, true);
writeAttributes(atts);
if (elementLevel == 1) {
forceNSDecls();
}
writeNSDecls();
write('>');
if ("html".equals(outputProperties.getProperty(METHOD, "xml"))
&& (localName.equals("script") || localName.equals("style"))) {
cdataElement = true;
}
super.startElement(uri, localName, qName, atts);
}
/**
* Write an end tag.
*
* Pass the event on down the filter chain for further processing.
*
* @param uri
* The Namespace URI, or the empty string if none is available.
* @param localName
* The element's local (unprefixed) name (required).
* @param qName
* The element's qualified (prefixed) name, or the empty string
* is none is available. This method will use the qName as a
* template for generating a prefix if necessary, but it is not
* guaranteed to use the same qName.
* @exception org.xml.sax.SAXException
* If there is an error writing the end tag, or if a handler
* further down the filter chain raises an exception.
* @see org.xml.sax.ContentHandler#endElement
*/
public void endElement(String uri, String localName, String qName)
throws SAXException {
if (!("html".equals(outputProperties.getProperty(METHOD, "xml"))
&& uri.equals("http://www.w3.org/1999/xhtml") && (localName
.equals("area")
|| localName.equals("base")
|| localName.equals("basefont")
|| localName.equals("br")
|| localName.equals("col")
|| localName.equals("frame")
|| localName.equals("hr")
|| localName.equals("img")
|| localName.equals("input")
|| localName.equals("isindex")
|| localName.equals("link")
|| localName.equals("meta") || localName.equals("param")))) {
write("</");
writeName(uri, localName, qName, true);
write('>');
}
if (elementLevel == 1) {
write('\n');
}
cdataElement = false;
super.endElement(uri, localName, qName);
nsSupport.popContext();
elementLevel--;
}
/**
* Write character data.
*
* Pass the event on down the filter chain for further processing.
*
* @param ch
* The array of characters to write.
* @param start
* The starting position in the array.
* @param length
* The number of characters to write.
* @exception org.xml.sax.SAXException
* If there is an error writing the characters, or if a
* handler further down the filter chain raises an exception.
* @see org.xml.sax.ContentHandler#characters
*/
public void characters(char ch[], int start, int len) throws SAXException {
if (!cdataElement) {
writeEsc(ch, start, len, false);
} else {
for (int i = start; i < start + len; i++) {
write(ch[i]);
}
}
super.characters(ch, start, len);
}
/**
* Write ignorable whitespace.
*
* Pass the event on down the filter chain for further processing.
*
* @param ch
* The array of characters to write.
* @param start
* The starting position in the array.
* @param length
* The number of characters to write.
* @exception org.xml.sax.SAXException
* If there is an error writing the whitespace, or if a
* handler further down the filter chain raises an exception.
* @see org.xml.sax.ContentHandler#ignorableWhitespace
*/
public void ignorableWhitespace(char ch[], int start, int length)
throws SAXException {
writeEsc(ch, start, length, false);
super.ignorableWhitespace(ch, start, length);
}
/**
* Write a processing instruction.
*
* Pass the event on down the filter chain for further processing.
*
* @param target
* The PI target.
* @param data
* The PI data.
* @exception org.xml.sax.SAXException
* If there is an error writing the PI, or if a handler
* further down the filter chain raises an exception.
* @see org.xml.sax.ContentHandler#processingInstruction
*/
public void processingInstruction(String target, String data)
throws SAXException {
write("<?");
write(target);
write(' ');
write(data);
write("?>");
if (elementLevel < 1) {
write('\n');
}
super.processingInstruction(target, data);
}
// //////////////////////////////////////////////////////////////////
// Additional markup.
// //////////////////////////////////////////////////////////////////
/**
* Write an empty element.
*
* This method writes an empty element tag rather than a start tag followed
* by an end tag. Both a {@link #startElement startElement} and an
* {@link #endElement endElement} event will be passed on down the filter
* chain.
*
* @param uri
* The element's Namespace URI, or the empty string if the
* element has no Namespace or if Namespace processing is not
* being performed.
* @param localName
* The element's local name (without prefix). This parameter must
* be provided.
* @param qName
* The element's qualified name (with prefix), or the empty
* string if none is available. This parameter is strictly
* advisory: the writer may or may not use the prefix attached.
* @param atts
* The element's attribute list.
* @exception org.xml.sax.SAXException
* If there is an error writing the empty tag, or if a
* handler further down the filter chain raises an exception.
* @see #startElement
* @see #endElement
*/
public void emptyElement(String uri, String localName, String qName,
Attributes atts) throws SAXException {
nsSupport.pushContext();
write('<');
writeName(uri, localName, qName, true);
writeAttributes(atts);
if (elementLevel == 1) {
forceNSDecls();
}
writeNSDecls();
write("/>");
super.startElement(uri, localName, qName, atts);
super.endElement(uri, localName, qName);
}
// //////////////////////////////////////////////////////////////////
// Convenience methods.
// //////////////////////////////////////////////////////////////////
/**
* Start a new element without a qname or attributes.
*
* <p>
* This method will provide a default empty attribute list and an empty
* string for the qualified name. It invokes {@link #startElement(String,
* String, String, Attributes)} directly.
* </p>
*
* @param uri
* The element's Namespace URI.
* @param localName
* The element's local name.
* @exception org.xml.sax.SAXException
* If there is an error writing the start tag, or if a
* handler further down the filter chain raises an exception.
* @see #startElement(String, String, String, Attributes)
*/
public void startElement(String uri, String localName) throws SAXException {
startElement(uri, localName, "", EMPTY_ATTS);
}
/**
* Start a new element without a qname, attributes or a Namespace URI.
*
* <p>
* This method will provide an empty string for the Namespace URI, and empty
* string for the qualified name, and a default empty attribute list. It
* invokes #startElement(String, String, String, Attributes)} directly.
* </p>
*
* @param localName
* The element's local name.
* @exception org.xml.sax.SAXException
* If there is an error writing the start tag, or if a
* handler further down the filter chain raises an exception.
* @see #startElement(String, String, String, Attributes)
*/
public void startElement(String localName) throws SAXException {
startElement("", localName, "", EMPTY_ATTS);
}
/**
* End an element without a qname.
*
* <p>
* This method will supply an empty string for the qName. It invokes
* {@link #endElement(String, String, String)} directly.
* </p>
*
* @param uri
* The element's Namespace URI.
* @param localName
* The element's local name.
* @exception org.xml.sax.SAXException
* If there is an error writing the end tag, or if a handler
* further down the filter chain raises an exception.
* @see #endElement(String, String, String)
*/
public void endElement(String uri, String localName) throws SAXException {
endElement(uri, localName, "");
}
/**
* End an element without a Namespace URI or qname.
*
* <p>
* This method will supply an empty string for the qName and an empty string
* for the Namespace URI. It invokes
* {@link #endElement(String, String, String)} directly.
* </p>
*
* @param localName
* The element's local name.
* @exception org.xml.sax.SAXException
* If there is an error writing the end tag, or if a handler
* further down the filter chain raises an exception.
* @see #endElement(String, String, String)
*/
public void endElement(String localName) throws SAXException {
endElement("", localName, "");
}
/**
* Add an empty element without a qname or attributes.
*
* <p>
* This method will supply an empty string for the qname and an empty
* attribute list. It invokes
* {@link #emptyElement(String, String, String, Attributes)} directly.
* </p>
*
* @param uri
* The element's Namespace URI.
* @param localName
* The element's local name.
* @exception org.xml.sax.SAXException
* If there is an error writing the empty tag, or if a
* handler further down the filter chain raises an exception.
* @see #emptyElement(String, String, String, Attributes)
*/
public void emptyElement(String uri, String localName) throws SAXException {
emptyElement(uri, localName, "", EMPTY_ATTS);
}
/**
* Add an empty element without a Namespace URI, qname or attributes.
*
* <p>
* This method will supply an empty string for the qname, and empty string
* for the Namespace URI, and an empty attribute list. It invokes
* {@link #emptyElement(String, String, String, Attributes)} directly.
* </p>
*
* @param localName
* The element's local name.
* @exception org.xml.sax.SAXException
* If there is an error writing the empty tag, or if a
* handler further down the filter chain raises an exception.
* @see #emptyElement(String, String, String, Attributes)
*/
public void emptyElement(String localName) throws SAXException {
emptyElement("", localName, "", EMPTY_ATTS);
}
/**
* Write an element with character data content.
*
* <p>
* This is a convenience method to write a complete element with character
* data content, including the start tag and end tag.
* </p>
*
* <p>
* This method invokes
* {@link #startElement(String, String, String, Attributes)}, followed by
* {@link #characters(String)}, followed by
* {@link #endElement(String, String, String)}.
* </p>
*
* @param uri
* The element's Namespace URI.
* @param localName
* The element's local name.
* @param qName
* The element's default qualified name.
* @param atts
* The element's attributes.
* @param content
* The character data content.
* @exception org.xml.sax.SAXException
* If there is an error writing the empty tag, or if a
* handler further down the filter chain raises an exception.
* @see #startElement(String, String, String, Attributes)
* @see #characters(String)
* @see #endElement(String, String, String)
*/
public void dataElement(String uri, String localName, String qName,
Attributes atts, String content) throws SAXException {
startElement(uri, localName, qName, atts);
characters(content);
endElement(uri, localName, qName);
}
/**
* Write an element with character data content but no attributes.
*
* <p>
* This is a convenience method to write a complete element with character
* data content, including the start tag and end tag. This method provides
* an empty string for the qname and an empty attribute list.
* </p>
*
* <p>
* This method invokes
* {@link #startElement(String, String, String, Attributes)}, followed by
* {@link #characters(String)}, followed by
* {@link #endElement(String, String, String)}.
* </p>
*
* @param uri
* The element's Namespace URI.
* @param localName
* The element's local name.
* @param content
* The character data content.
* @exception org.xml.sax.SAXException
* If there is an error writing the empty tag, or if a
* handler further down the filter chain raises an exception.
* @see #startElement(String, String, String, Attributes)
* @see #characters(String)
* @see #endElement(String, String, String)
*/
public void dataElement(String uri, String localName, String content)
throws SAXException {
dataElement(uri, localName, "", EMPTY_ATTS, content);
}
/**
* Write an element with character data content but no attributes or
* Namespace URI.
*
* <p>
* This is a convenience method to write a complete element with character
* data content, including the start tag and end tag. The method provides an
* empty string for the Namespace URI, and empty string for the qualified
* name, and an empty attribute list.
* </p>
*
* <p>
* This method invokes
* {@link #startElement(String, String, String, Attributes)}, followed by
* {@link #characters(String)}, followed by
* {@link #endElement(String, String, String)}.
* </p>
*
* @param localName
* The element's local name.
* @param content
* The character data content.
* @exception org.xml.sax.SAXException
* If there is an error writing the empty tag, or if a
* handler further down the filter chain raises an exception.
* @see #startElement(String, String, String, Attributes)
* @see #characters(String)
* @see #endElement(String, String, String)
*/
public void dataElement(String localName, String content)
throws SAXException {
dataElement("", localName, "", EMPTY_ATTS, content);
}
/**
* Write a string of character data, with XML escaping.
*
* <p>
* This is a convenience method that takes an XML String, converts it to a
* character array, then invokes {@link #characters(char[], int, int)}.
* </p>
*
* @param data
* The character data.
* @exception org.xml.sax.SAXException
* If there is an error writing the string, or if a handler
* further down the filter chain raises an exception.
* @see #characters(char[], int, int)
*/
public void characters(String data) throws SAXException {
char ch[] = data.toCharArray();
characters(ch, 0, ch.length);
}
// //////////////////////////////////////////////////////////////////
// Internal methods.
// //////////////////////////////////////////////////////////////////
/**
* Force all Namespaces to be declared.
*
* This method is used on the root element to ensure that the predeclared
* Namespaces all appear.
*/
private void forceNSDecls() {
Enumeration prefixes = forcedDeclTable.keys();
while (prefixes.hasMoreElements()) {
String prefix = (String) prefixes.nextElement();
doPrefix(prefix, null, true);
}
}
/**
* Determine the prefix for an element or attribute name.
*
* TODO: this method probably needs some cleanup.
*
* @param uri
* The Namespace URI.
* @param qName
* The qualified name (optional); this will be used to indicate
* the preferred prefix if none is currently bound.
* @param isElement
* true if this is an element name, false if it is an attribute
* name (which cannot use the default Namespace).
*/
private String doPrefix(String uri, String qName, boolean isElement) {
String defaultNS = nsSupport.getURI("");
if ("".equals(uri)) {
if (isElement && defaultNS != null)
nsSupport.declarePrefix("", "");
return null;
}
String prefix;
if (isElement && defaultNS != null && uri.equals(defaultNS)) {
prefix = "";
} else {
prefix = nsSupport.getPrefix(uri);
}
if (prefix != null) {
return prefix;
}
prefix = (String) doneDeclTable.get(uri);
if (prefix != null
&& ((!isElement || defaultNS != null) && "".equals(prefix) || nsSupport
.getURI(prefix) != null)) {
prefix = null;
}
if (prefix == null) {
prefix = (String) prefixTable.get(uri);
if (prefix != null
&& ((!isElement || defaultNS != null) && "".equals(prefix) || nsSupport
.getURI(prefix) != null)) {
prefix = null;
}
}
if (prefix == null && qName != null && !"".equals(qName)) {
int i = qName.indexOf(':');
if (i == -1) {
if (isElement && defaultNS == null) {
prefix = "";
}
} else {
prefix = qName.substring(0, i);
}
}
for (; prefix == null || nsSupport.getURI(prefix) != null; prefix = "__NS"
+ ++prefixCounter)
;
nsSupport.declarePrefix(prefix, uri);
doneDeclTable.put(uri, prefix);
return prefix;
}
/**
* Write a raw character.
*
* @param c
* The character to write.
* @exception org.xml.sax.SAXException
* If there is an error writing the character, this method
* will throw an IOException wrapped in a SAXException.
*/
private void write(char c) throws SAXException {
try {
output.write(c);
} catch (IOException e) {
throw new SAXException(e);
}
}
/**
* Write a raw string.
*
* @param s
* @exception org.xml.sax.SAXException
* If there is an error writing the string, this method will
* throw an IOException wrapped in a SAXException
*/
private void write(String s) throws SAXException {
try {
output.write(s);
} catch (IOException e) {
throw new SAXException(e);
}
}
/**
* Write out an attribute list, escaping values.
*
* The names will have prefixes added to them.
*
* @param atts
* The attribute list to write.
* @exception org.xml.SAXException
* If there is an error writing the attribute list, this
* method will throw an IOException wrapped in a
* SAXException.
*/
private void writeAttributes(Attributes atts) throws SAXException {
int len = atts.getLength();
for (int i = 0; i < len; i++) {
char ch[] = atts.getValue(i).toCharArray();
write(' ');
writeName(atts.getURI(i), atts.getLocalName(i), atts.getQName(i),
false);
write("=\"");
writeEsc(ch, 0, ch.length, true);
write('"');
}
}
/**
* Write an array of data characters with escaping.
*
* @param ch
* The array of characters.
* @param start
* The starting position.
* @param length
* The number of characters to use.
* @param isAttVal
* true if this is an attribute value literal.
* @exception org.xml.SAXException
* If there is an error writing the characters, this method
* will throw an IOException wrapped in a SAXException.
*/
private void writeEsc(char ch[], int start, int length, boolean isAttVal)
throws SAXException {
for (int i = start; i < start + length; i++) {
switch (ch[i]) {
case '&':
write("&");
break;
case '<':
write("<");
break;
case '>':
write(">");
break;
case '\"':
if (isAttVal) {
write(""");
} else {
write('\"');
}
break;
default:
write(ch[i]);
}
}
}
/**
* Write out the list of Namespace declarations.
*
* @exception org.xml.sax.SAXException
* This method will throw an IOException wrapped in a
* SAXException if there is an error writing the Namespace
* declarations.
*/
private void writeNSDecls() throws SAXException {
Enumeration prefixes = nsSupport.getDeclaredPrefixes();
while (prefixes.hasMoreElements()) {
String prefix = (String) prefixes.nextElement();
String uri = nsSupport.getURI(prefix);
if (uri == null) {
uri = "";
}
char ch[] = uri.toCharArray();
write(' ');
if ("".equals(prefix)) {
write("xmlns=\"");
} else {
write("xmlns:");
write(prefix);
write("=\"");
}
writeEsc(ch, 0, ch.length, true);
write('\"');
}
}
/**
* Write an element or attribute name.
*
* @param uri
* The Namespace URI.
* @param localName
* The local name.
* @param qName
* The prefixed name, if available, or the empty string.
* @param isElement
* true if this is an element name, false if it is an attribute
* name.
* @exception org.xml.sax.SAXException
* This method will throw an IOException wrapped in a
* SAXException if there is an error writing the name.
*/
private void writeName(String uri, String localName, String qName,
boolean isElement) throws SAXException {
String prefix = doPrefix(uri, qName, isElement);
if (prefix != null && !"".equals(prefix)) {
write(prefix);
write(':');
}
if (localName != null && !"".equals(localName)) {
write(localName);
} else {
int i = qName.indexOf(':');
write(qName.substring(i + 1, qName.length()));
}
}
// //////////////////////////////////////////////////////////////////
// Default LexicalHandler implementation
// //////////////////////////////////////////////////////////////////
public void comment(char[] ch, int start, int length) throws SAXException {
write("<!--");
for (int i = start; i < start + length; i++) {
write(ch[i]);
if (ch[i] == '-' && i + 1 <= start + length && ch[i + 1] == '-')
write(' ');
}
write("-->");
}
public void endCDATA() throws SAXException {
}
public void endDTD() throws SAXException {
}
public void endEntity(String name) throws SAXException {
}
public void startCDATA() throws SAXException {
}
public void startDTD(String name, String publicId, String systemId)
throws SAXException {
}
public void startEntity(String name) throws SAXException {
}
// //////////////////////////////////////////////////////////////////
// Output properties
// //////////////////////////////////////////////////////////////////
public String getOutputProperty(String key) {
return outputProperties.getProperty(key);
}
public void setOutputProperty(String key, String value) {
outputProperties.setProperty(key, value);
}
// //////////////////////////////////////////////////////////////////
// Constants.
// //////////////////////////////////////////////////////////////////
private final Attributes EMPTY_ATTS = new AttributesImpl();
public static final String CDATA_SECTION_ELEMENTS = "cdata-section-elements";
public static final String DOCTYPE_PUBLIC = "doctype-public";
public static final String DOCTYPE_SYSTEM = "doctype-system";
public static final String ENCODING = "encoding";
public static final String INDENT = "indent";
public static final String MEDIA_TYPE = "media-type";
public static final String METHOD = "method";
public static final String OMIT_XML_DECLARATION = "omit-xml-declaration";
public static final String STANDALONE = "standalone";
public static final String VERSION = "version";
// //////////////////////////////////////////////////////////////////
// Internal state.
// //////////////////////////////////////////////////////////////////
private Hashtable prefixTable;
private Hashtable forcedDeclTable;
private Hashtable doneDeclTable;
private int elementLevel = 0;
private Writer output;
private NamespaceSupport nsSupport;
private int prefixCounter = 0;
private Properties outputProperties;
private boolean cdataElement = false;
}
// end of XMLWriter.java
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