javax.swing.text.html.parser

Class Parser

public class Parser extends Object implements DTDConstants

A simple error-tolerant HTML parser that uses a DTD document to access data on the possible tokens, arguments and syntax.

The parser reads an HTML content from a Reader and calls various notifying methods (which should be overridden in a subclass) when tags or data are encountered.

Some HTML elements need no opening or closing tags. The task of this parser is to invoke the tag handling methods also when the tags are not explicitly specified and must be supposed using information, stored in the DTD. For example, parsing the document

<table><tr><td>a<td>b<td>c</tr>
will invoke exactly the handling methods exactly in the same order (and with the same parameters) as if parsing the document:
<html><head></head><body><table>< tbody><tr><td>a</td><td>b </td><td>c</td></tr>< /tbody></table></body></html>

(supposed tags are given in italics). The parser also supports obsolete elements of HTML syntax.

Field Summary
protected DTD	dtd The document template description that will be used to parse the documents.
protected boolean	strict The value of this field determines whether or not the Parser will be strict in enforcing SGML compatibility.

Constructor Summary
	Parser(DTD a_dtd) Creates a new parser that uses the given DTD to access data on the possible tokens, arguments and syntax.

Method Summary
protected void	endTag(boolean omitted) The method is called when the HTML end (closing) tag is found or if the parser concludes that the one should be present in the current position.
protected void	error(String msg) Invokes the error handler.
protected void	error(String msg, String invalid) Invokes the error handler.
protected void	error(String parm1, String parm2, String parm3) Invokes the error handler.
protected void	error(String parm1, String parm2, String parm3, String parm4) Invokes the error handler.
protected void	flushAttributes() In this implementation, this is never called and returns without action.
protected SimpleAttributeSet	getAttributes() Get the attributes of the current tag.
protected int	getCurrentLine() Get the number of the document line being parsed.
protected int	getCurrentPos() Get the current position in the document being parsed.
protected void	handleComment(char[] comment) Handle HTML comment.
protected void	handleEmptyTag(TagElement tag) Handle the tag with no content, like <br>.
protected void	handleEndTag(TagElement tag) The method is called when the HTML closing tag ((like </table>) is found or if the parser concludes that the one should be present in the current position.
protected void	handleEOFInComment() This is additionally called in when the HTML content terminates without closing the HTML comment.
protected void	handleError(int line, String message)
protected void	handleStartTag(TagElement tag) The method is called when the HTML opening tag ((like <table>) is found or if the parser concludes that the one should be present in the current position.
protected void	handleText(char[] text) Handle the text section.
protected void	handleTitle(char[] title) Handle HTML <title> tag.
protected TagElement	makeTag(Element element) Constructs the tag from the given element.
protected TagElement	makeTag(Element element, boolean isSupposed) Constructs the tag from the given element.
protected void	markFirstTime(Element element) This is called when the tag, representing the given element, occurs first time in the document.
void	parse(Reader reader) Parse the HTML text, calling various methods in response to the occurence of the corresponding HTML constructions.
String	parseDTDMarkup() Parses DTD markup declaration.
protected boolean	parseMarkupDeclarations(StringBuffer strBuff) Parse DTD document declarations.
protected void	startTag(TagElement tag) The method is called when the HTML opening tag ((like <table>) is found or if the parser concludes that the one should be present in the current position.

Field Detail

dtd

protected DTD dtd

The document template description that will be used to parse the documents.

strict

protected boolean strict

The value of this field determines whether or not the Parser will be strict in enforcing SGML compatibility. The default value is false, stating that the parser should do everything to parse and get at least some information even from the incorrectly written HTML input.

Constructor Detail

Parser

public Parser(DTD a_dtd)

Creates a new parser that uses the given DTD to access data on the possible tokens, arguments and syntax. There is no single - step way to get a default DTD; you must either refer to the implementation - specific packages, write your own DTD or obtain the working instance of parser in other way, for example, by calling {@link javax.swing.text.html.HTMLEditorKit#getParser() }.

Parameters: a_dtd A DTD to use.

Method Detail

endTag

protected void endTag(boolean omitted)

The method is called when the HTML end (closing) tag is found or if the parser concludes that the one should be present in the current position. The method is called immediatly before calling the handleEndTag().

Parameters: omitted True if the tag is no actually present in the document, but is supposed by the parser (like </html> at the end of the document).

error

protected void error(String msg)

Invokes the error handler. The default method in this implementation finally delegates the call to handleError, also providing the number of the current line.

error

protected void error(String msg, String invalid)

Invokes the error handler. The default method in this implementation finally delegates the call to error (msg+": '"+invalid+"'").

error

protected void error(String parm1, String parm2, String parm3)

Invokes the error handler. The default method in this implementation finally delegates the call to error (parm1+" "+ parm2+" "+ parm3).

error

protected void error(String parm1, String parm2, String parm3, String parm4)

Invokes the error handler. The default method in this implementation finally delegates the call to error (parm1+" "+ parm2+" "+ parm3+" "+ parm4).

flushAttributes

protected void flushAttributes()

In this implementation, this is never called and returns without action.

getAttributes

protected SimpleAttributeSet getAttributes()

Get the attributes of the current tag.

Returns: The attribute set, representing the attributes of the current tag.

getCurrentLine

protected int getCurrentLine()

Get the number of the document line being parsed.

Returns: The current line.

getCurrentPos

protected int getCurrentPos()

Get the current position in the document being parsed.

Returns: The current position.

handleComment

protected void handleComment(char[] comment)

Handle HTML comment. The default method returns without action.

Parameters: comment The comment being handled

handleEmptyTag

protected void handleEmptyTag(TagElement tag)

Handle the tag with no content, like <br>. The method is called for the elements that, in accordance with the current DTD, has an empty content.

Parameters: tag The tag being handled.

Throws: javax.swing.text.ChangedCharSetException

handleEndTag

protected void handleEndTag(TagElement tag)

The method is called when the HTML closing tag ((like </table>) is found or if the parser concludes that the one should be present in the current position.

Parameters: tag The tag being handled

handleEOFInComment

protected void handleEOFInComment()

This is additionally called in when the HTML content terminates without closing the HTML comment. This can only happen if the HTML document contains errors (for example, the closing --;gt is missing. The default method calls the error handler.

handleError

protected void handleError(int line, String message)

handleStartTag

protected void handleStartTag(TagElement tag)

The method is called when the HTML opening tag ((like <table>) is found or if the parser concludes that the one should be present in the current position.

Parameters: tag The tag being handled

handleText

protected void handleText(char[] text)

Handle the text section.

For non-preformatted section, the parser replaces \t, \r and \n by spaces and then multiple spaces by a single space. Additionaly, all whitespace around tags is discarded.

For pre-formatted text (inside TEXAREA and PRE), the parser preserves all tabs and spaces, but removes one bounding \r, \n or \r\n, if it is present. Additionally, it replaces each occurence of \r or \r\n by a single \n.

Parameters: text A section text.

handleTitle

protected void handleTitle(char[] title)

Handle HTML <title> tag. This method is invoked when both title starting and closing tags are already behind. The passed argument contains the concatenation of all title text sections.

Parameters: title The title text.

makeTag

protected TagElement makeTag(Element element)

Constructs the tag from the given element. In this implementation, this is defined, but never called.

Parameters: element the base element of the tag.

Returns: the tag

makeTag

protected TagElement makeTag(Element element, boolean isSupposed)

Constructs the tag from the given element.

Parameters: element the tag base {@link javax.swing.text.html.parser.Element} isSupposed true if the tag is not actually present in the html input, but the parser supposes that it should to occur in the current location.

Returns: the tag

markFirstTime

protected void markFirstTime(Element element)

This is called when the tag, representing the given element, occurs first time in the document.

Parameters: element

parse

public void parse(Reader reader)

Parse the HTML text, calling various methods in response to the occurence of the corresponding HTML constructions.

Parameters: reader The reader to read the source HTML from.

Throws: IOException If the reader throws one.

parseDTDMarkup

public String parseDTDMarkup()

Parses DTD markup declaration. Currently returns without action.

Returns: null.

Throws: java.io.IOException

parseMarkupDeclarations

protected boolean parseMarkupDeclarations(StringBuffer strBuff)

Parse DTD document declarations. Currently only parses the document type declaration markup.

Parameters: strBuff

Returns: true if this is a valid DTD markup declaration.

Throws: IOException

startTag

protected void startTag(TagElement tag)

The method is called when the HTML opening tag ((like <table>) is found or if the parser concludes that the one should be present in the current position. The method is called immediately before calling the handleStartTag.

Parameters: tag The tag