org.dom4j.io

Class HTMLWriter

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 {@link OutputFormat OutputFormat}for details. Here are the rules for this class based on an OutputFormat, "format", passed in to the constructor:

Examples

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

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

Basically, {@link OutputFormat.isXHTML() OutputFormat.isXHTML()} == true will produce valid XML, while {@link org.dom4j.io.OutputFormat#isExpandEmptyElements() 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: {@link#setPreformattedTags(java.util.Set) setPreformattedTags}

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:
{@link #prettyPrintHTML(String) prettyPrintHTML(String)}or
{@link #prettyPrintHTML(String,boolean,boolean,boolean,boolean) prettyPrintHTML(String,boolean,boolean,boolean,boolean)} or,
{@link #prettyPrintXHTML(String) 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 {@link #setPreformattedTags(java.util.Set) 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 OutputFormatDEFAULT_HTML_FORMAT
protected static HashSetDEFAULT_PREFORMATTED_TAGS
Constructor Summary
HTMLWriter(Writer writer)
HTMLWriter(Writer writer, OutputFormat format)
HTMLWriter()
HTMLWriter(OutputFormat format)
HTMLWriter(OutputStream out)
HTMLWriter(OutputStream out, OutputFormat format)
Method Summary
voidendCDATA()
SetgetOmitElementCloseSet()
A clone of the Set of elements that can have their close-tags omitted.
SetgetPreformattedTags()
booleanisPreformattedTag(String qualifiedName)
DOCUMENT ME!
protected voidloadOmitElementCloseSet(Set set)
protected booleanomitElementClose(String qualifiedName)
static StringprettyPrintHTML(String html)
Convenience method to just get a String result.
static StringprettyPrintHTML(String html, boolean newlines, boolean trim, boolean isXHTML, boolean expandEmpty)
DOCUMENT ME!
static StringprettyPrintXHTML(String html)
Convenience method to just get a String result, but As XHTML .
voidsetOmitElementCloseSet(Set newSet)
To use the empty set, pass an empty Set, or null:
 
 
       setOmitElementCloseSet(new HashSet());
     or
       setOmitElementCloseSet(null);
 
  
 
voidsetPreformattedTags(Set newSet)

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

voidstartCDATA()
protected voidwriteCDATA(String text)
protected voidwriteClose(String qualifiedName)
Overriden method to not close certain element names to avoid wierd behaviour from browsers for versions up to 5.x
protected voidwriteDeclaration()
protected voidwriteElement(Element element)
This override handles any elements that should not remove whitespace, such as <PRE>, <SCRIPT>, <STYLE>, and <TEXTAREA>.
protected voidwriteEmptyElementClose(String qualifiedName)
protected voidwriteEntity(Entity entity)
protected voidwriteString(String text)

Field Detail

DEFAULT_HTML_FORMAT

protected static final OutputFormat DEFAULT_HTML_FORMAT

DEFAULT_PREFORMATTED_TAGS

protected static final HashSet DEFAULT_PREFORMATTED_TAGS

Constructor Detail

HTMLWriter

public HTMLWriter(Writer writer)

HTMLWriter

public HTMLWriter(Writer writer, OutputFormat format)

HTMLWriter

public HTMLWriter()

HTMLWriter

public HTMLWriter(OutputFormat format)

HTMLWriter

public HTMLWriter(OutputStream out)

HTMLWriter

public HTMLWriter(OutputStream out, OutputFormat format)

Method Detail

endCDATA

public void endCDATA()

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.

getPreformattedTags

public Set getPreformattedTags()

See Also: setPreformattedTags

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

loadOmitElementCloseSet

protected void loadOmitElementCloseSet(Set set)

omitElementClose

protected boolean omitElementClose(String qualifiedName)

prettyPrintHTML

public static String prettyPrintHTML(String html)
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: java.io.IOException java.io.UnsupportedEncodingException org.dom4j.DocumentException

prettyPrintHTML

public static String prettyPrintHTML(String html, boolean newlines, boolean trim, boolean isXHTML, boolean expandEmpty)
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: java.io.IOException java.io.UnsupportedEncodingException org.dom4j.DocumentException

prettyPrintXHTML

public static String prettyPrintXHTML(String html)
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: java.io.IOException java.io.UnsupportedEncodingException org.dom4j.DocumentException

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!

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!

startCDATA

public void startCDATA()

writeCDATA

protected void writeCDATA(String text)

writeClose

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

Parameters: qualifiedName DOCUMENT ME!

Throws: IOException DOCUMENT ME!

writeDeclaration

protected void writeDeclaration()

writeElement

protected void writeElement(Element element)
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.

Parameters: element DOCUMENT ME!

Throws: IOException When the stream could not be written to.

See Also: setPreformattedTags

writeEmptyElementClose

protected void writeEmptyElementClose(String qualifiedName)

writeEntity

protected void writeEntity(Entity entity)

writeString

protected void writeString(String text)
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