Module java.desktop
Package javax.swing.text.html.parser

Class Parser

java.lang.Object
javax.swing.text.html.parser.Parser
All Implemented Interfaces:
DTDConstants
Direct Known Subclasses:
DocumentParser
public class Parser
extends Object
implements DTDConstants
A simple DTD-driven HTML parser. The parser reads an HTML file from an InputStream and calls various methods (which should be overridden in a subclass) when tags and data are encountered.

Unfortunately there are many badly implemented HTML parsers out there, and as a result there are many badly formatted HTML files. This parser attempts to parse most HTML files. This means that the implementation sometimes deviates from the SGML specification in favor of HTML.

The parser treats \r and \r\n as \n. Newlines after starttags and before end tags are ignored just as specified in the SGML/HTML specification.

The html spec does not specify how spaces are to be coalesced very well. Specifically, the following scenarios are not discussed (note that a space should be used here, but I am using &nbsp to force the space to be displayed):

'<b>blah <i> <strike> foo' which can be treated as: '<b>blah <i><strike>foo'

as well as: '<p><a href="xx"> <em>Using</em></a></p>' which appears to be treated as: '<p><a href="xx"><em>Using</em></a></p>'

If strict is false, when a tag that breaks flow, (TagElement.breaksFlows) or trailing whitespace is encountered, all whitespace will be ignored until a non whitespace character is encountered. This appears to give behavior closer to the popular browsers.

See Also:
DTD, TagElement, SimpleAttributeSet

  • Field Details

    • dtd

      protected DTD dtd
      The dtd.

    • strict

      protected boolean strict
      This flag determines whether or not the Parser will be strict in enforcing SGML compatibility. If false, it will be lenient with certain common classes of erroneous HTML constructs. Strict or not, in either case an error will be recorded.

  • Constructor Details

    • Parser

      public Parser​(DTD dtd)
      Creates parser with the specified dtd.
      Parameters:
      dtd - the dtd.

  • Method Details

    • getCurrentLine

      protected int getCurrentLine()
      Returns:
      the line number of the line currently being parsed

    • makeTag

      protected TagElement makeTag​(Element elem, boolean fictional)
      Makes a TagElement.
      Parameters:
      elem - the element storing the tag definition
      fictional - the value of the flag "fictional" to be set for the tag
      Returns:
      the created TagElement

    • makeTag

      protected TagElement makeTag​(Element elem)
      Makes a TagElement.
      Parameters:
      elem - the element storing the tag definition
      Returns:
      the created TagElement

    • getAttributes

      protected SimpleAttributeSet getAttributes()
      Returns attributes for the current tag.
      Returns:
      SimpleAttributeSet containing the attributes

    • flushAttributes

      protected void flushAttributes()
      Removes the current attributes.

    • handleText

      protected void handleText​(char[] text)
      Called when PCDATA is encountered.
      Parameters:
      text - the section text

    • handleTitle

      protected void handleTitle​(char[] text)
      Called when an HTML title tag is encountered.
      Parameters:
      text - the title text

    • handleComment

      protected void handleComment​(char[] text)
      Called when an HTML comment is encountered.
      Parameters:
      text - the comment being handled

    • handleEOFInComment

      protected void handleEOFInComment()
      Called when the content terminates without closing the HTML comment.

    • handleEmptyTag

      protected void handleEmptyTag​(TagElement tag) throws ChangedCharSetException
      Called when an empty tag is encountered.
      Parameters:
      tag - the tag being handled
      Throws:
      ChangedCharSetException - if the document charset was changed

    • handleStartTag

      protected void handleStartTag​(TagElement tag)
      Called when a start tag is encountered.
      Parameters:
      tag - the tag being handled

    • handleEndTag

      protected void handleEndTag​(TagElement tag)
      Called when an end tag is encountered.
      Parameters:
      tag - the tag being handled

    • handleError

      protected void handleError​(int ln, String msg)
      An error has occurred.
      Parameters:
      ln - the number of line containing the error
      msg - the error message

    • error

      protected void error​(String err, String arg1, String arg2, String arg3)
      Invokes the error handler.
      Parameters:
      err - the error type
      arg1 - the 1st error message argument
      arg2 - the 2nd error message argument
      arg3 - the 3rd error message argument

    • error

      protected void error​(String err, String arg1, String arg2)
      Invokes the error handler with the 3rd error message argument "?".
      Parameters:
      err - the error type
      arg1 - the 1st error message argument
      arg2 - the 2nd error message argument

    • error

      protected void error​(String err, String arg1)
      Invokes the error handler with the 2nd and 3rd error message argument "?".
      Parameters:
      err - the error type
      arg1 - the 1st error message argument

    • error

      protected void error​(String err)
      Invokes the error handler with the 1st, 2nd and 3rd error message argument "?".
      Parameters:
      err - the error type

    • startTag

      protected void startTag​(TagElement tag) throws ChangedCharSetException
      Handle a start tag. The new tag is pushed onto the tag stack. The attribute list is checked for required attributes.
      Parameters:
      tag - the tag
      Throws:
      ChangedCharSetException - if the document charset was changed

    • endTag

      protected void endTag​(boolean omitted)
      Handle an end tag. The end tag is popped from the tag stack.
      Parameters:
      omitted - true if the tag is no actually present in the document, but is supposed by the parser

    • markFirstTime

      protected void markFirstTime​(Element elem)
      Marks the first time a tag has been seen in a document
      Parameters:
      elem - the element represented by the tag

    • parseDTDMarkup

      public String parseDTDMarkup() throws IOException
      Parses the Document Type Declaration markup declaration. Currently ignores it.
      Returns:
      the string representation of the markup declaration
      Throws:
      IOException - if an I/O error occurs

    • parseMarkupDeclarations

      protected boolean parseMarkupDeclarations​(StringBuffer strBuff) throws IOException
      Parse markup declarations. Currently only handles the Document Type Declaration markup. Returns true if it is a markup declaration false otherwise.
      Parameters:
      strBuff - the markup declaration
      Returns:
      true if this is a valid markup declaration; otherwise false
      Throws:
      IOException - if an I/O error occurs

    • parse

      public void parse​(Reader in) throws IOException
      Parse an HTML stream, given a DTD.
      Parameters:
      in - the reader to read the source from
      Throws:
      IOException - if an I/O error occurs

    • getCurrentPos

      protected int getCurrentPos()
      Returns the current position.
      Returns:
      the current position