Module java.desktop

Class DocumentParser

All Implemented Interfaces:

public class DocumentParser extends Parser
A Parser for HTML Documents (actually, you can specify a DTD, but you should really only use this class with the html dtd in swing). Reads an InputStream of HTML and invokes the appropriate methods in the ParserCallback class. This is the default parser used by HTMLEditorKit to parse HTML url's.

This will message the callback for all valid tags, as well as tags that are implied but not explicitly specified. For example, the html string (<p>blah) only has a p tag defined. The callback will see the following methods:

  1. handleStartTag(html, ...)
  2. handleStartTag(head, ...)
  3. handleEndTag(head)
  4. handleStartTag(body, ...)
  5. handleStartTag(p, ...)
  6. handleText(...)
  7. handleEndTag(p)
  8. handleEndTag(body)
  9. handleEndTag(html)
The items in italic are implied, that is, although they were not explicitly specified, to be correct html they should have been present (head isn't necessary, but it is still generated). For tags that are implied, the AttributeSet argument will have a value of Boolean.TRUE for the key HTMLEditorKit.ParserCallback.IMPLIED.

HTML.Attributes defines a type safe enumeration of html attributes. If an attribute key of a tag is defined in HTML.Attribute, the HTML.Attribute will be used as the key, otherwise a String will be used. For example <p foo=bar class=neat> has two attributes. foo is not defined in HTML.Attribute, where as class is, therefore the AttributeSet will have two values in it, HTML.Attribute.CLASS with a String value of 'neat' and the String key 'foo' with a String value of 'bar'.

The position argument will indicate the start of the tag, comment or text. Similar to arrays, the first character in the stream has a position of 0. For tags that are implied the position will indicate the location of the next encountered tag. In the first example, the implied start body and html tags will have the same position as the p tag, and the implied end p, html and body tags will all have the same position.

As html skips whitespace the position for text will be the position of the first valid character, eg in the string '\n\n\nblah' the text 'blah' will have a position of 3, the newlines are skipped.

For attributes that do not have a value, eg in the html string <foo blah> the attribute blah does not have a value, there are two possible values that will be placed in the AttributeSet's value:

  • If the DTD does not contain an definition for the element, or the definition does not have an explicit value then the value in the AttributeSet will be HTML.NULL_ATTRIBUTE_VALUE.
  • If the DTD contains an explicit value, as in: <!ATTLIST OPTION selected (selected) #IMPLIED> this value from the dtd (in this case selected) will be used.

Once the stream has been parsed, the callback is notified of the most likely end of line string. The end of line string will be one of \n, \r or \r\n, which ever is encountered the most in parsing the stream.

  • Constructor Details

    • DocumentParser

      public DocumentParser(DTD dtd)
      Creates document parser with the specified dtd.
      dtd - the dtd.
  • Method Details

    • parse

      public void parse(Reader in, HTMLEditorKit.ParserCallback callback, boolean ignoreCharSet) throws IOException
      Parse an HTML stream, given a DTD.
      in - the reader to read the source from
      callback - the callback
      ignoreCharSet - if true the charset is ignored
      IOException - if an I/O error occurs
    • handleStartTag

      protected void handleStartTag(TagElement tag)
      Handle Start Tag.
      handleStartTag in class Parser
      tag - the tag being handled
    • handleEmptyTag

      protected void handleEmptyTag(TagElement tag) throws ChangedCharSetException
      Handle Empty Tag.
      handleEmptyTag in class Parser
      tag - the tag being handled
      ChangedCharSetException - if the document charset was changed
    • handleEndTag

      protected void handleEndTag(TagElement tag)
      Handle End Tag.
      handleEndTag in class Parser
      tag - the tag being handled
    • handleText

      protected void handleText(char[] data)
      Handle Text.
      handleText in class Parser
      data - the section text