HTMLWriter (dom4j 1.6.1 API)

dom4j API

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org.dom4j.io Class HTMLWriter

java.lang.Object
  extended byorg.xml.sax.helpers.XMLFilterImpl
      extended byorg.dom4j.io.XMLWriter
          extended byorg.dom4j.io.HTMLWriter
All Implemented Interfaces:
ContentHandler, DTDHandler, EntityResolver, ErrorHandler, LexicalHandler, XMLFilter, XMLReader
public class HTMLWriter
extends XMLWriter

HTMLWriter takes a DOM4J tree and formats it to a stream as HTML. This formatter is similar to XMLWriter but it outputs the text of CDATA and Entity sections rather than the serialised format as in XML, it has an XHTML mode, it retains whitespace in certain elements such as <PRE>, and it supports certain elements which have no corresponding close tag such as for <BR> and <P>.

The OutputFormat passed in to the constructor is checked for isXHTML() and isExpandEmptyElements(). See OutputFormatfor details. Here are the rules for this class based on an OutputFormat, "format", passed in to the constructor:

  • If an element is in getOmitElementCloseSet, then it is treated specially:
    • It never expands, since some browsers treat this as two separate Horizontal Rules: <HR></HR>
    • If format.isXHTML(), then it has a space before the closing single-tag slash, since Netscape 4.x- treats this: <HR /> as an element named "HR" with an attribute named "/", but that's better than when it refuses to recognize this: <hr/> which it thinks is an element named "HR/".
  • If format.isXHTML(), all elements must have either a close element, or be a closed single tag.
  • If format.isExpandEmptyElements()() is true, all elements are expanded except as above.
Examples

If isXHTML == true, CDATA sections look like this: 

 
 <myelement><![CDATA[My data]]></myelement>
Otherwise, they look like this: 
 
 <myelement>My data</myelement>

Basically, OutputFormat.isXHTML() == true will produce valid XML, while format.isExpandEmptyElements() determines whether empty elements are expanded if isXHTML is true, excepting the special HTML single tags.

Also, HTMLWriter handles tags whose contents should be preformatted, that is, whitespace-preserved. By default, this set includes the tags <PRE>, <SCRIPT>, <STYLE>, and <TEXTAREA>, case insensitively. It does not include <IFRAME>. Other tags, such as <CODE>, <KBD>, <TT>, <VAR>, are usually rendered in a different font in most browsers, but don't preserve whitespace, so they also don't appear in the default list. HTML Comments are always whitespace-preserved. However, the parser you use may store comments with linefeed-only text nodes (\n) even if your platform uses another line.separator character, and HTMLWriter outputs Comment nodes exactly as the DOM is set up by the parser. See examples and discussion here:

Examples

Pretty Printing

This example shows how to pretty print a string containing a valid HTML document to a string. You can also just call the static methods of this class:
prettyPrintHTML(String)or
prettyPrintHTML(String,boolean,boolean,boolean,boolean) or,
prettyPrintXHTML(String)for XHTML (note the X) 

 String testPrettyPrint(String html) {
     StringWriter sw = new StringWriter();
     OutputFormat format = OutputFormat.createPrettyPrint();
     // These are the default values for createPrettyPrint,
     // so you needn't set them:
     // format.setNewlines(true);
     // format.setTrimText(true);</font>
     format.setXHTML(true);
     HTMLWriter writer = new HTMLWriter(sw, format);
     Document document = DocumentHelper.parseText(html);
     writer.write(document);
     writer.flush();
     return sw.toString();
 }

This example shows how to create a "squeezed" document, but one that will work in browsers even if the browser line length is limited. No newlines are included, no extra whitespace at all, except where it it required by setPreformattedTags. 

 String testCrunch(String html) {
     StringWriter sw = new StringWriter();
     OutputFormat format = OutputFormat.createPrettyPrint();
     format.setNewlines(false);
     format.setTrimText(true);
     format.setIndent("");
     format.setXHTML(true);
     format.setExpandEmptyElements(false);
     format.setNewLineAfterNTags(20);
     org.dom4j.io.HTMLWriter writer = new HTMLWriter(sw, format);
     org.dom4j.Document document = DocumentHelper.parseText(html);
     writer.write(document);
     writer.flush();
     return sw.toString();
 }

Version:
$Revision: 1.21 $
Author:
James Strachan , Laramie Crocker

Field Summary
protected static OutputFormat DEFAULT_HTML_FORMAT
           
protected static HashSet DEFAULT_PREFORMATTED_TAGS
           
 
Fields inherited from class org.dom4j.io.XMLWriter
DEFAULT_FORMAT, lastOutputNodeType, LEXICAL_HANDLER_NAMES, preserve, writer
 
Constructor Summary
HTMLWriter()
           
HTMLWriter(OutputFormat format)
           
HTMLWriter(OutputStream out)
           
HTMLWriter(OutputStream out, OutputFormat format)
           
HTMLWriter(Writer writer)
           
HTMLWriter(Writer writer, OutputFormat format)
           
 
Method Summary
 void endCDATA()
           
 Set getOmitElementCloseSet()
          A clone of the Set of elements that can have their close-tags omitted.
 Set getPreformattedTags()
           
 boolean isPreformattedTag(String qualifiedName)
          DOCUMENT ME!
protected  void loadOmitElementCloseSet(Set set)
           
protected  boolean omitElementClose(String qualifiedName)
           
static String prettyPrintHTML(String html)
          Convenience method to just get a String result.
static String prettyPrintHTML(String html, boolean newlines, boolean trim, boolean isXHTML, boolean expandEmpty)
          DOCUMENT ME!
static String prettyPrintXHTML(String html)
          Convenience method to just get a String result, but As XHTML .
 void setOmitElementCloseSet(Set newSet)
          To use the empty set, pass an empty Set, or null: setOmitElementCloseSet(new HashSet()); or setOmitElementCloseSet(null);
 void setPreformattedTags(Set newSet)
           Override the default set, which includes PRE, SCRIPT, STYLE, and TEXTAREA, case insensitively.
 void startCDATA()
           
protected  void writeCDATA(String text)
           
protected  void writeClose(String qualifiedName)
          Overriden method to not close certain element names to avoid wierd behaviour from browsers for versions up to 5.x
protected  void writeDeclaration()
           This will write the declaration to the given Writer.
protected  void writeElement(Element element)
          This override handles any elements that should not remove whitespace, such as <PRE>, <SCRIPT>, <STYLE>, and <TEXTAREA>.
protected  void writeEmptyElementClose(String qualifiedName)
           
protected  void writeEntity(Entity entity)
           
protected  void writeString(String text)
           
 
Methods inherited from class org.dom4j.io.XMLWriter
characters, close, comment, createWriter, defaultMaximumAllowedCharacter, endDocument, endDTD, endElement, endEntity, endPrefixMapping, escapeAttributeEntities, escapeElementEntities, flush, getLexicalHandler, getMaximumAllowedCharacter, getOutputFormat, getProperty, handleException, ignorableWhitespace, indent, installLexicalHandler, isElementSpacePreserved, isEscapeText, isExpandEmptyElements, isNamespaceDeclaration, notationDecl, parse, println, processingInstruction, resolveEntityRefs, setDocumentLocator, setEscapeText, setIndentLevel, setLexicalHandler, setMaximumAllowedCharacter, setOutputStream, setProperty, setResolveEntityRefs, setWriter, shouldEncodeChar, startDocument, startDTD, startElement, startEntity, startPrefixMapping, unparsedEntityDecl, write, write, write, write, write, write, write, write, write, write, write, write, write, writeAttribute, writeAttribute, writeAttributes, writeAttributes, writeClose, writeComment, writeDocType, writeDocType, writeElementContent, writeEntityRef, writeEscapeAttributeEntities, writeNamespace, writeNamespace, writeNamespaces, writeNode, writeNodeText, writeOpen, writePrintln, writeProcessingInstruction
 
Methods inherited from class org.xml.sax.helpers.XMLFilterImpl
error, fatalError, getContentHandler, getDTDHandler, getEntityResolver, getErrorHandler, getFeature, getParent, parse, resolveEntity, setContentHandler, setDTDHandler, setEntityResolver, setErrorHandler, setFeature, setParent, skippedEntity, warning
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

DEFAULT_PREFORMATTED_TAGS

protected static final HashSet DEFAULT_PREFORMATTED_TAGS

DEFAULT_HTML_FORMAT

protected static final OutputFormat DEFAULT_HTML_FORMAT
Constructor Detail

HTMLWriter

public HTMLWriter(Writer writer)

HTMLWriter

public HTMLWriter(Writer writer,
                  OutputFormat format)

HTMLWriter

public HTMLWriter()
           throws UnsupportedEncodingException

HTMLWriter

public HTMLWriter(OutputFormat format)
           throws UnsupportedEncodingException

HTMLWriter

public HTMLWriter(OutputStream out)
           throws UnsupportedEncodingException

HTMLWriter

public HTMLWriter(OutputStream out,
                  OutputFormat format)
           throws UnsupportedEncodingException
Method Detail

startCDATA

public void startCDATA()
                throws SAXException
Specified by:
startCDATA in interface LexicalHandler
Overrides:
startCDATA in class XMLWriter
Throws:
SAXException

endCDATA

public void endCDATA()
              throws SAXException
Specified by:
endCDATA in interface LexicalHandler
Overrides:
endCDATA in class XMLWriter
Throws:
SAXException

writeCDATA

protected void writeCDATA(String text)
                   throws IOException
Overrides:
writeCDATA in class XMLWriter
Throws:
IOException

writeEntity

protected void writeEntity(Entity entity)
                    throws IOException
Overrides:
writeEntity in class XMLWriter
Throws:
IOException

writeDeclaration

protected void writeDeclaration()
                         throws IOException
Description copied from class: XMLWriter

This will write the declaration to the given Writer. Assumes XML version 1.0 since we don't directly know.

Overrides:
writeDeclaration in class XMLWriter
Throws:
IOException - DOCUMENT ME!

writeString

protected void writeString(String text)
                    throws IOException
Overrides:
writeString in class XMLWriter
Throws:
IOException

writeClose

protected void writeClose(String qualifiedName)
                   throws IOException
Overriden method to not close certain element names to avoid wierd behaviour from browsers for versions up to 5.x

Overrides:
writeClose in class XMLWriter
Parameters:
qualifiedName - DOCUMENT ME!
Throws:
IOException - DOCUMENT ME!

writeEmptyElementClose

protected void writeEmptyElementClose(String qualifiedName)
                               throws IOException
Overrides:
writeEmptyElementClose in class XMLWriter
Throws:
IOException

omitElementClose

protected boolean omitElementClose(String qualifiedName)

loadOmitElementCloseSet

protected void loadOmitElementCloseSet(Set set)

getOmitElementCloseSet

public Set getOmitElementCloseSet()
A clone of the Set of elements that can have their close-tags omitted. By default it should be "AREA", "BASE", "BR", "COL", "HR", "IMG", "INPUT", "LINK", "META", "P", "PARAM"

Returns:
A clone of the Set.

setOmitElementCloseSet

public void setOmitElementCloseSet(Set newSet)
To use the empty set, pass an empty Set, or null: 
 
 
       setOmitElementCloseSet(new HashSet());
     or
       setOmitElementCloseSet(null);

Parameters:
newSet - DOCUMENT ME!

getPreformattedTags

public Set getPreformattedTags()
See Also:
setPreformattedTags

setPreformattedTags

public void setPreformattedTags(Set newSet)

Override the default set, which includes PRE, SCRIPT, STYLE, and TEXTAREA, case insensitively.

Setting Preformatted Tags

Pass in a Set of Strings, one for each tag name that should be treated like a PRE tag. You may pass in null or an empty Set to assign the empty set, in which case no tags will be treated as preformatted, except that HTML Comments will continue to be preformatted. If a tag is included in the set of preformatted tags, all whitespace within the tag will be preserved, including whitespace on the same line preceding the close tag. This will generally make the close tag not line up with the start tag, but it preserves the intention of the whitespace within the tag.

The browser considers leading whitespace before the close tag to be significant, but leading whitespace before the open tag to be insignificant. For example, if the HTML author doesn't put the close TEXTAREA tag flush to the left margin, then the TEXTAREA control in the browser will have spaces on the last line inside the control. This may be the HTML author's intent. Similarly, in a PRE, the browser treats a flushed left close PRE tag as different from a close tag with leading whitespace. Again, this must be left up to the HTML author.

Examples

Here is an example of how you can set the PreformattedTags list using setPreformattedTags to include IFRAME, as well as the default set, if you have an instance of this class named myHTMLWriter: 

 Set current = myHTMLWriter.getPreformattedTags();
 current.add("IFRAME");
 myHTMLWriter.setPreformattedTags(current);
 
 //The set is now <b>PRE, SCRIPT, STYLE, TEXTAREA, IFRAME</b>
Similarly, you can simply replace it with your own: 
 
 
       HashSet newset = new HashSet();
       newset.add("PRE");
       newset.add("TEXTAREA");
       myHTMLWriter.setPreformattedTags(newset);
 
       //The set is now <b>{PRE, TEXTAREA}</b>
You can remove all tags from the preformatted tags list, with an empty set, like this: 
 
 
       myHTMLWriter.setPreformattedTags(new HashSet());
 
       //The set is now <b>{}</b>
or with null, like this: 
 
 
       myHTMLWriter.setPreformattedTags(null);
 
       //The set is now <b>{}</b>

Parameters:
newSet - DOCUMENT ME!

isPreformattedTag

public boolean isPreformattedTag(String qualifiedName)
DOCUMENT ME!

Parameters:
qualifiedName - DOCUMENT ME!
Returns:
true if the qualifiedName passed in matched (case-insensitively) a tag in the preformattedTags set, or false if not found or if the set is empty or null.
See Also:
setPreformattedTags

writeElement

protected void writeElement(Element element)
                     throws IOException
This override handles any elements that should not remove whitespace, such as <PRE>, <SCRIPT>, <STYLE>, and <TEXTAREA>. Note: the close tags won't line up with the open tag, but we can't alter that. See javadoc note at setPreformattedTags.

Overrides:
writeElement in class XMLWriter
Parameters:
element - DOCUMENT ME!
Throws:
IOException - When the stream could not be written to.
See Also:
setPreformattedTags

prettyPrintHTML

public static String prettyPrintHTML(String html)
                              throws IOException,
                                     UnsupportedEncodingException,
                                     DocumentException
Convenience method to just get a String result.

Parameters:
html - DOCUMENT ME!
Returns:
a pretty printed String from the source string, preserving whitespace in the defaultPreformattedTags set, and leaving the close tags off of the default omitElementCloseSet set. Use one of the write methods if you want stream output.
Throws:
IOException
UnsupportedEncodingException
DocumentException

prettyPrintXHTML

public static String prettyPrintXHTML(String html)
                               throws IOException,
                                      UnsupportedEncodingException,
                                      DocumentException
Convenience method to just get a String result, but As XHTML .

Parameters:
html - DOCUMENT ME!
Returns:
a pretty printed String from the source string, preserving whitespace in the defaultPreformattedTags set, but conforming to XHTML: no close tags are omitted (though if empty, they will be converted to XHTML empty tags: <HR/> Use one of the write methods if you want stream output.
Throws:
IOException
UnsupportedEncodingException
DocumentException

prettyPrintHTML

public static String prettyPrintHTML(String html,
                                     boolean newlines,
                                     boolean trim,
                                     boolean isXHTML,
                                     boolean expandEmpty)
                              throws IOException,
                                     UnsupportedEncodingException,
                                     DocumentException
DOCUMENT ME!

Parameters:
html - DOCUMENT ME!
newlines - DOCUMENT ME!
trim - DOCUMENT ME!
isXHTML - DOCUMENT ME!
expandEmpty - DOCUMENT ME!
Returns:
a pretty printed String from the source string, preserving whitespace in the defaultPreformattedTags set, and leaving the close tags off of the default omitElementCloseSet set. This override allows you to specify various formatter options. Use one of the write methods if you want stream output.
Throws:
IOException
UnsupportedEncodingException
DocumentException
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