Top Description Fields Constructors Methods
org.glassfish.jaxb.core.marshaller

public Class XMLWriter

extends XMLFilterImpl
Class Inheritance
Known Direct Subclasses
org.glassfish.jaxb.core.marshaller.DataWriter
Imports
java.io.IOException, .OutputStreamWriter, .Writer, java.util.HashMap, .Map, org.xml.sax.Attributes, .SAXException, org.xml.sax.helpers.AttributesImpl, .XMLFilterImpl

Filter to write an XML document from a SAX event stream.

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.

The client creates a document by invoking the methods for standard SAX2 events, always beginning with the startDocument method and ending with the 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

w.startElement("foo");

is equivalent to the regular SAX2 ContentHandler method

w.startElement("", "foo", "", new AttributesImpl());

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:

XMLWriter w = new XMLWriter();

w.startDocument();
w.startElement("greeting");
w.characters("Hello, world!");
w.endElement("greeting");
w.endDocument();

The resulting document will look like this:

<?xml version="1.0" standalone="yes"?>

<greeting>Hello, world!</greeting>

In fact, there is an even simpler convenience method, dataElement, designed for writing elements that contain only character data, so the code to generate the document could be shortened to

XMLWriter w = new XMLWriter();

w.startDocument();
w.dataElement("greeting", "Hello, world!");
w.endDocument();

Whitespace

According to the XML Recommendation, all 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

w.dataElement("item", "1");
w.dataElement("item", "2");
w.dataElement("item", "3");

you will end up with

<item>1</item><item>3</item><item>3</item>

You need to invoke one of the characters methods explicitly to add newlines or indentation. Alternatively, you can use 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).

Namespace Support

The writer contains extensive support for XML Namespaces, so that a client application does not have to keep track of prefixes and supply xmlns 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:

w.startDocument();
w.emptyElement("http://www.foo.com/ns/", "foo");
w.endDocument();

The resulting document will look like this:

<?xml version="1.0" standalone="yes"?>

<_NS1:foo xmlns:_NS1="http://www.foo.com/ns/"/>

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:

  1. the qualified name

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).

The resulting document will look like this:

<?xml version="1.0" standalone="yes"?>

<foo:foo xmlns:foo="http://www.foo.com/ns/"/>

The default Namespace simply uses an empty string as the prefix:

w.setPrefix("http://www.foo.com/ns/", "");
w.startDocument();
w.emptyElement("http://www.foo.com/ns/", "foo");
w.endDocument();

The resulting document will look like this:

<?xml version="1.0" standalone="yes"?>

<foo xmlns="http://www.foo.com/ns/"/>

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:

<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>

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:

w.forceNSDecl("http://www.purl.org/dc/");

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:

<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>

This approach is also useful for declaring Namespace prefixes that be used by qualified names appearing in attribute values or character data.

Author
David Megginson, [email protected]
Since
JAXB 1.0
Version
0.2
See Also
org.xml.sax.XMLFilter, org.xml.sax.ContentHandler

Field Summary

Modifier and TypeField and Description
private int
private final Attributes
private String
private final CharacterEscapeHandler
private String
header

This string will be written right after the xml declaration without any escaping.

private final HashMap<String, String>
private Writer
private boolean
private boolean

Constructor Summary

AccessConstructor and Description
public
XMLWriter(Writer
The output destination, or null to use standard output.
writer
,
String
If non-null string is specified, it is written as a part of the XML declaration.
encoding
,
CharacterEscapeHandler _escapeHandler)

Create a new XML writer.

public
XMLWriter(Writer writer, String encoding)

Method Summary

Modifier and TypeMethod and Description
public void
characters(char[]
The array of characters to write.
ch
,
int
The starting position in the array.
start
,
int
The number of characters to write.
len
)

Overrides org.xml.sax.helpers.XMLFilterImpl.characters.

Implements org.xml.sax.ContentHandler.characters.

Write character data.

public void
characters(String
The character data.
data
)

Write a string of character data, with XML escaping.

public void
dataElement(String
The element's Namespace URI.
uri
,
String
The element's local name.
localName
,
String
The element's default qualified name.
qName
,
Attributes
The element's attributes.
atts
,
String
The character data content.
content
)

Write an element with character data content.

public void
dataElement(String
The element's Namespace URI.
uri
,
String
The element's local name.
localName
,
String
The character data content.
content
)

Write an element with character data content but no attributes.

public void
dataElement(String
The element's local name.
localName
,
String
The character data content.
content
)

Write an element with character data content but no attributes or Namespace URI.

public void
endDocument()

Overrides org.xml.sax.helpers.XMLFilterImpl.endDocument.

Implements org.xml.sax.ContentHandler.endDocument.

Write a newline at the end of the document.

public void
endElement(String
The Namespace URI, or the empty string if none is available.
uri
,
String
The element's local (unprefixed) name (required).
localName
,
String
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.
qName
)

Overrides org.xml.sax.helpers.XMLFilterImpl.endElement.

Implements org.xml.sax.ContentHandler.endElement.

Write an end tag.

public void
endElement(String
The element's Namespace URI.
uri
,
String
The element's local name.
localName
)

End an element without a qname.

public void
endElement(String
The element's local name.
localName
)

End an element without a Namespace URI or qname.

public void
flush()

Flush the output.

public void
ignorableWhitespace(char[]
The array of characters to write.
ch
,
int
The starting position in the array.
start
,
int
The number of characters to write.
length
)

Overrides org.xml.sax.helpers.XMLFilterImpl.ignorableWhitespace.

Implements org.xml.sax.ContentHandler.ignorableWhitespace.

Write ignorable whitespace.

private void
init(Writer
The output destination, or null to use standard output.
writer
,
String encoding)

Internal initialization method.

public void
processingInstruction(String
The PI target.
target
,
String
The PI data.
data
)

Overrides org.xml.sax.helpers.XMLFilterImpl.processingInstruction.

Implements org.xml.sax.ContentHandler.processingInstruction.

Write a processing instruction.

public void
reset()

Reset the writer.

public void
setHeader(String
passing null will work as if the empty string is passed.
_header
)

Sets the header string.

public void
setOutput(Writer
The output destination, or null to use standard output.
writer
,
String _encoding)

Set a new output destination for the document.

public void
setXmlDecl(boolean _writeXmlDecl)

Set whether the writer should print out the XML declaration (<?xml version='1.0' ...

public void
startDocument()

Overrides org.xml.sax.helpers.XMLFilterImpl.startDocument.

Implements org.xml.sax.ContentHandler.startDocument.

Write the XML declaration at the beginning of the document.

public void
startElement(String
The Namespace URI, or the empty string if none is available.
uri
,
String
The element's local (unprefixed) name (required).
localName
,
String
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.
qName
,
Attributes
The element's attribute list (must not be null).
atts
)

Overrides org.xml.sax.helpers.XMLFilterImpl.startElement.

Implements org.xml.sax.ContentHandler.startElement.

Write a start tag.

public void
startElement(String
The element's Namespace URI.
uri
,
String
The element's local name.
localName
)

Start a new element without a qname or attributes.

public void
startElement(String
The element's local name.
localName
)

Start a new element without a qname, attributes or a Namespace URI.

public void
startPrefixMapping(String prefix, String uri)

Overrides org.xml.sax.helpers.XMLFilterImpl.startPrefixMapping.

Implements org.xml.sax.ContentHandler.startPrefixMapping.

Filter a start Namespace prefix mapping event.

protected final void
write(char
The character to write.
c
)

Write a raw character.

protected final void
write(String s)

Write a raw string.

private void
writeAttributes(Attributes
The attribute list to write.
atts
)

Write out an attribute list, escaping values.

private void
writeEsc(char[]
The array of characters.
ch
,
int
The starting position.
start
,
int
The number of characters to use.
length
,
boolean
true if this is an attribute value literal.
isAttVal
)

Write an array of data characters with escaping.

protected void
Inherited from org.xml.sax.helpers.XMLFilterImpl:
endPrefixMappingerrorfatalErrorgetContentHandlergetDTDHandlergetEntityResolvergetErrorHandlergetFeaturegetParentgetPropertynotationDeclparseparseresolveEntitysetContentHandlersetDocumentLocatorsetDTDHandlersetEntityResolversetErrorHandlersetFeaturesetParentsetPropertyskippedEntityunparsedEntityDeclwarning

Field Detail

elementLevelback to summary
private int elementLevel
EMPTY_ATTSback to summary
private final Attributes EMPTY_ATTS
encodingback to summary
private String encoding
escapeHandlerback to summary
private final CharacterEscapeHandler escapeHandler
locallyDeclaredPrefixback to summary
private final HashMap<String, String> locallyDeclaredPrefix
outputback to summary
private Writer output
startTagIsClosedback to summary
private boolean startTagIsClosed
writeXmlDeclback to summary
private boolean writeXmlDecl

Constructor Detail

XMLWriterback to summary
public XMLWriter(Writer writer, String encoding, CharacterEscapeHandler _escapeHandler)

Create a new XML writer.

Write to the writer provided.

Parameters
writer:Writer

The output destination, or null to use standard output.

encoding:String

If non-null string is specified, it is written as a part of the XML declaration.

XMLWriterback to summary
public XMLWriter(Writer writer, String encoding)

Method Detail

charactersback to summary
public void characters(char[] ch, int start, int len) throws SAXException

Overrides org.xml.sax.helpers.XMLFilterImpl.characters.

Implements org.xml.sax.ContentHandler.characters.

Write character data. Pass the event on down the filter chain for further processing.

Parameters
ch:char[]

The array of characters to write.

start:int

The starting position in the array.

len:int

The number of characters to write.

Annotations
@Override
Exceptions
SAXException:
If there is an error writing the characters, or if a handler further down the filter chain raises an exception.
See Also
org.xml.sax.ContentHandler#characters(char[], int, int)
charactersback to summary
public void characters(String data) throws SAXException

Write a string of character data, with XML escaping.

This is a convenience method that takes an XML String, converts it to a character array, then invokes characters(char[], int, int).

Parameters
data:String

The character data.

Exceptions
SAXException:
If there is an error writing the string, or if a handler further down the filter chain raises an exception.
See Also
characters(char[], int, int)
dataElementback to summary
public void dataElement(String uri, String localName, String qName, Attributes atts, String content) throws SAXException

Write an element with character data content.

This is a convenience method to write a complete element with character data content, including the start tag and end tag.

This method invokes startElement(String, String, String, Attributes), followed by characters(String), followed by endElement(String, String, String).

Parameters
uri:String

The element's Namespace URI.

localName:String

The element's local name.

qName:String

The element's default qualified name.

atts:Attributes

The element's attributes.

content:String

The character data content.

Exceptions
SAXException:
If there is an error writing the empty tag, or if a handler further down the filter chain raises an exception.
See Also
startElement(String, String, String, Attributes), characters(String), endElement(String, String, String)
dataElementback to summary
public void dataElement(String uri, String localName, String content) throws SAXException

Write an element with character data content but no attributes.

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.

This method invokes startElement(String, String, String, Attributes), followed by characters(String), followed by endElement(String, String, String).

Parameters
uri:String

The element's Namespace URI.

localName:String

The element's local name.

content:String

The character data content.

Exceptions
SAXException:
If there is an error writing the empty tag, or if a handler further down the filter chain raises an exception.
See Also
startElement(String, String, String, Attributes), characters(String), endElement(String, String, String)
dataElementback to summary
public void dataElement(String localName, String content) throws SAXException

Write an element with character data content but no attributes or Namespace URI.

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.

This method invokes startElement(String, String, String, Attributes), followed by characters(String), followed by endElement(String, String, String).

Parameters
localName:String

The element's local name.

content:String

The character data content.

Exceptions
SAXException:
If there is an error writing the empty tag, or if a handler further down the filter chain raises an exception.
See Also
startElement(String, String, String, Attributes), characters(String), endElement(String, String, String)
endDocumentback to summary
public void endDocument() throws SAXException

Overrides org.xml.sax.helpers.XMLFilterImpl.endDocument.

Implements org.xml.sax.ContentHandler.endDocument.

Write a newline at the end of the document. Pass the event on down the filter chain for further processing.

Annotations
@Override
Exceptions
SAXException:
If there is an error writing the newline, or if a handler further down the filter chain raises an exception.
See Also
org.xml.sax.ContentHandler#endDocument()
endElementback to summary
public void endElement(String uri, String localName, String qName) throws SAXException

Overrides org.xml.sax.helpers.XMLFilterImpl.endElement.

Implements org.xml.sax.ContentHandler.endElement.

Write an end tag. Pass the event on down the filter chain for further processing.

Parameters
uri:String

The Namespace URI, or the empty string if none is available.

localName:String

The element's local (unprefixed) name (required).

qName:String

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.

Annotations
@Override
Exceptions
SAXException:
If there is an error writing the end tag, or if a handler further down the filter chain raises an exception.
See Also
org.xml.sax.ContentHandler#endElement(java.lang.String, java.lang.String, java.lang.String)
endElementback to summary
public void endElement(String uri, String localName) throws SAXException

End an element without a qname.

This method will supply an empty string for the qName. It invokes endElement(String, String, String) directly.

Parameters
uri:String

The element's Namespace URI.

localName:String

The element's local name.

Exceptions
SAXException:
If there is an error writing the end tag, or if a handler further down the filter chain raises an exception.
See Also
endElement(String, String, String)
endElementback to summary
public void endElement(String localName) throws SAXException

End an element without a Namespace URI or qname.

This method will supply an empty string for the qName and an empty string for the Namespace URI. It invokes endElement(String, String, String) directly.

Parameters
localName:String

The element's local name.

Exceptions
SAXException:
If there is an error writing the end tag, or if a handler further down the filter chain raises an exception.
See Also
endElement(String, String, String)
flushback to summary
public void flush() throws IOException

Flush the output.

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.

This method is invoked automatically by the endDocument method after writing a document.

See Also
reset()
ignorableWhitespaceback to summary
public void ignorableWhitespace(char[] ch, int start, int length) throws SAXException

Overrides org.xml.sax.helpers.XMLFilterImpl.ignorableWhitespace.

Implements org.xml.sax.ContentHandler.ignorableWhitespace.

Write ignorable whitespace. Pass the event on down the filter chain for further processing.

Parameters
ch:char[]

The array of characters to write.

start:int

The starting position in the array.

length:int

The number of characters to write.

Annotations
@Override
Exceptions
SAXException:
If there is an error writing the whitespace, or if a handler further down the filter chain raises an exception.
See Also
org.xml.sax.ContentHandler#ignorableWhitespace(char[], int, int)
initback to summary
private void init(Writer writer, String encoding)

Internal initialization method.

All of the public constructors invoke this method.

Parameters
writer:Writer

The output destination, or null to use standard output.

processingInstructionback to summary
public void processingInstruction(String target, String data) throws SAXException

Overrides org.xml.sax.helpers.XMLFilterImpl.processingInstruction.

Implements org.xml.sax.ContentHandler.processingInstruction.

Write a processing instruction. Pass the event on down the filter chain for further processing.

Parameters
target:String

The PI target.

data:String

The PI data.

Annotations
@Override
Exceptions
SAXException:
If there is an error writing the PI, or if a handler further down the filter chain raises an exception.
See Also
org.xml.sax.ContentHandler#processingInstruction(java.lang.String, java.lang.String)
resetback to summary
public void reset()

Reset the writer.

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 flush before resetting the writer, to make sure that no output is lost.

This method is invoked automatically by the startDocument method before writing a new document.

Note

this method will not clear the prefix or URI information in the writer or the selected output writer.

See Also
flush()
setHeaderback to summary
public void setHeader(String _header)

Sets the header string. This string will be written right after the xml declaration without any escaping. Useful for generating a boiler-plate DOCTYPE decl, PIs, and comments.

Parameters
_header:String

passing null will work as if the empty string is passed.

setOutputback to summary
public void setOutput(Writer writer, String _encoding)

Set a new output destination for the document.

Parameters
writer:Writer

The output destination, or null to use standard output.

See Also
flush()
setXmlDeclback to summary
public void setXmlDecl(boolean _writeXmlDecl)

Set whether the writer should print out the XML declaration (<?xml version='1.0' ... ?>).

This option is set to true by default.

startDocumentback to summary
public void startDocument() throws SAXException

Overrides org.xml.sax.helpers.XMLFilterImpl.startDocument.

Implements org.xml.sax.ContentHandler.startDocument.

Write the XML declaration at the beginning of the document. Pass the event on down the filter chain for further processing.

Annotations
@Override
Exceptions
SAXException:
If there is an error writing the XML declaration, or if a handler further down the filter chain raises an exception.
See Also
org.xml.sax.ContentHandler#startDocument()
startElementback to summary
public void startElement(String uri, String localName, String qName, Attributes atts) throws SAXException

Overrides org.xml.sax.helpers.XMLFilterImpl.startElement.

Implements org.xml.sax.ContentHandler.startElement.

Write a start tag. Pass the event on down the filter chain for further processing.

Parameters
uri:String

The Namespace URI, or the empty string if none is available.

localName:String

The element's local (unprefixed) name (required).

qName:String

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.

atts:Attributes

The element's attribute list (must not be null).

Annotations
@Override
Exceptions
SAXException:
If there is an error writing the start tag, or if a handler further down the filter chain raises an exception.
See Also
org.xml.sax.ContentHandler#startElement(java.lang.String, java.lang.String, java.lang.String, org.xml.sax.Attributes)
startElementback to summary
public void startElement(String uri, String localName) throws SAXException

Start a new element without a qname or attributes.

This method will provide a default empty attribute list and an empty string for the qualified name. It invokes startElement(String, String, String, Attributes) directly.

Parameters
uri:String

The element's Namespace URI.

localName:String

The element's local name.

Exceptions
SAXException:
If there is an error writing the start tag, or if a handler further down the filter chain raises an exception.
See Also
startElement(String, String, String, Attributes)
startElementback to summary
public void startElement(String localName) throws SAXException

Start a new element without a qname, attributes or a Namespace URI.

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.

Parameters
localName:String

The element's local name.

Exceptions
SAXException:
If there is an error writing the start tag, or if a handler further down the filter chain raises an exception.
See Also
startElement(String, String, String, Attributes)
startPrefixMappingback to summary
public void startPrefixMapping(String prefix, String uri) throws SAXException

Overrides org.xml.sax.helpers.XMLFilterImpl.startPrefixMapping.

Implements org.xml.sax.ContentHandler.startPrefixMapping.

Doc from org.xml.sax.helpers.XMLFilterImpl.startPrefixMapping.

Filter a start Namespace prefix mapping event.

Annotations
@Override
Exceptions
SAXException:
The client may throw an exception during processing.
writeback to summary
protected final void write(char c) throws IOException

Write a raw character.

Parameters
c:char

The character to write.

writeback to summary
protected final void write(String s) throws IOException

Write a raw string.

writeAttributesback to summary
private void writeAttributes(Attributes atts) throws IOException

Write out an attribute list, escaping values. The names will have prefixes added to them.

Parameters
atts:Attributes

The attribute list to write.

writeEscback to summary
private void writeEsc(char[] ch, int start, int length, boolean isAttVal) throws IOException

Write an array of data characters with escaping.

Parameters
ch:char[]

The array of characters.

start:int

The starting position.

length:int

The number of characters to use.

isAttVal:boolean

true if this is an attribute value literal.

writeXmlDeclback to summary
protected void writeXmlDecl(String decl) throws IOException