Class 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 OutputFormat.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: setPreformattedTags(java.util.Set) 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 $
  • Field Details

    • lineSeparator

      private static String lineSeparator
    • DEFAULT_PREFORMATTED_TAGS

      protected static final HashSet<String> DEFAULT_PREFORMATTED_TAGS
    • DEFAULT_HTML_FORMAT

      protected static final OutputFormat DEFAULT_HTML_FORMAT
    • formatStack

      private Stack<HTMLWriter.FormatState> formatStack
    • lastText

      private String lastText
    • tagsOuput

      private int tagsOuput
    • newLineAfterNTags

      private int newLineAfterNTags
    • preformattedTags

      private HashSet<String> preformattedTags
    • omitElementCloseSet

      private HashSet<String> omitElementCloseSet
      Used to store the qualified element names which should have no close element tag
  • Constructor Details

  • Method Details

    • 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)
    • internalGetOmitElementCloseSet

      private HashSet<String> internalGetOmitElementCloseSet()
    • loadOmitElementCloseSet

      protected void loadOmitElementCloseSet(Set<String> set)
    • getOmitElementCloseSet

      public Set<String> 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<String> 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<String> getPreformattedTags()
      Returns:
      DOCUMENT ME!
      See Also:
    • setPreformattedTags

      public void setPreformattedTags(Set<String> 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:
    • 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:
    • justSpaces

      private String justSpaces(String text)
    • lazyInitNewLinesAfterNTags

      private void lazyInitNewLinesAfterNTags()
    • 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 - DOCUMENT ME!
      UnsupportedEncodingException - DOCUMENT ME!
      DocumentException - DOCUMENT ME!
    • 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 - DOCUMENT ME!
      UnsupportedEncodingException - DOCUMENT ME!
      DocumentException - DOCUMENT ME!
    • 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 - DOCUMENT ME!
      UnsupportedEncodingException - DOCUMENT ME!
      DocumentException - DOCUMENT ME!