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

Class HTMLDocument.HTMLReader

java.lang.Object
javax.swing.text.html.HTMLEditorKit.ParserCallback
javax.swing.text.html.HTMLDocument.HTMLReader
Enclosing class:
HTMLDocument
public class HTMLDocument.HTMLReader extends HTMLEditorKit.ParserCallback
An HTML reader to load an HTML document with an HTML element structure. This is a set of callbacks from the parser, implemented to create a set of elements tagged with attributes. The parse builds up tokens (ElementSpec) that describe the element subtree desired, and burst it into the document under the protection of a write lock using the insert method on the document outer class.

The reader can be configured by registering actions (of type HTMLDocument.HTMLReader.TagAction) that describe how to handle the action. The idea behind the actions provided is that the most natural text editing operations can be provided if the element structure boils down to paragraphs with runs of some kind of style in them. Some things are more naturally specified structurally, so arbitrary structure should be allowed above the paragraphs, but will need to be edited with structural actions. The implication of this is that some of the HTML elements specified in the stream being parsed will be collapsed into attributes, and in some cases paragraphs will be synthesized. When HTML elements have been converted to attributes, the attribute key will be of type HTML.Tag, and the value will be of type AttributeSet so that no information is lost. This enables many of the existing actions to work so that the user can type input, hit the return key, backspace, delete, etc and have a reasonable result. Selections can be created, and attributes applied or removed, etc. With this in mind, the work done by the reader can be categorized into the following kinds of tasks:

Block
Build the structure like it's specified in the stream. This produces elements that contain other elements.
Paragraph
Like block except that it's expected that the element will be used with a paragraph view so a paragraph element won't need to be synthesized.
Character
Contribute the element as an attribute that will start and stop at arbitrary text locations. This will ultimately be mixed into a run of text, with all of the currently flattened HTML character elements.
Special
Produce an embedded graphical element.
Form
Produce an element that is like the embedded graphical element, except that it also has a component model associated with it.
Hidden
Create an element that is hidden from view when the document is being viewed read-only, and visible when the document is being edited. This is useful to keep the model from losing information, and used to store things like comments and unrecognized tags.

Currently, <APPLET>, <PARAM>, <MAP>, <AREA>, <LINK>, <SCRIPT> and <STYLE> are unsupported.

The assignment of the actions described is shown in the following table for the tags defined in HTML.Tag.

HTML tags and assigned actions
Tag Action
HTML.Tag.A CharacterAction
HTML.Tag.ADDRESS CharacterAction
HTML.Tag.APPLET HiddenAction
HTML.Tag.AREA AreaAction
HTML.Tag.B CharacterAction
HTML.Tag.BASE BaseAction
HTML.Tag.BASEFONT CharacterAction
HTML.Tag.BIG CharacterAction
HTML.Tag.BLOCKQUOTE BlockAction
HTML.Tag.BODY BlockAction
HTML.Tag.BR SpecialAction
HTML.Tag.CAPTION BlockAction
HTML.Tag.CENTER BlockAction
HTML.Tag.CITE CharacterAction
HTML.Tag.CODE CharacterAction
HTML.Tag.DD BlockAction
HTML.Tag.DFN CharacterAction
HTML.Tag.DIR BlockAction
HTML.Tag.DIV BlockAction
HTML.Tag.DL BlockAction
HTML.Tag.DT ParagraphAction
HTML.Tag.EM CharacterAction
HTML.Tag.FONT CharacterAction
HTML.Tag.FORM As of 1.4 a BlockAction
HTML.Tag.FRAME SpecialAction
HTML.Tag.FRAMESET BlockAction
HTML.Tag.H1 ParagraphAction
HTML.Tag.H2 ParagraphAction
HTML.Tag.H3 ParagraphAction
HTML.Tag.H4 ParagraphAction
HTML.Tag.H5 ParagraphAction
HTML.Tag.H6 ParagraphAction
HTML.Tag.HEAD HeadAction
HTML.Tag.HR SpecialAction
HTML.Tag.HTML BlockAction
HTML.Tag.I CharacterAction
HTML.Tag.IMG SpecialAction
HTML.Tag.INPUT FormAction
HTML.Tag.ISINDEX IsndexAction
HTML.Tag.KBD CharacterAction
HTML.Tag.LI BlockAction
HTML.Tag.LINK LinkAction
HTML.Tag.MAP MapAction
HTML.Tag.MENU BlockAction
HTML.Tag.META MetaAction
HTML.Tag.NOFRAMES BlockAction
HTML.Tag.OBJECT SpecialAction
HTML.Tag.OL BlockAction
HTML.Tag.OPTION FormAction
HTML.Tag.P ParagraphAction
HTML.Tag.PARAM HiddenAction
HTML.Tag.PRE PreAction
HTML.Tag.SAMP CharacterAction
HTML.Tag.SCRIPT HiddenAction
HTML.Tag.SELECT FormAction
HTML.Tag.SMALL CharacterAction
HTML.Tag.STRIKE CharacterAction
HTML.Tag.S CharacterAction
HTML.Tag.STRONG CharacterAction
HTML.Tag.STYLE StyleAction
HTML.Tag.SUB CharacterAction
HTML.Tag.SUP CharacterAction
HTML.Tag.TABLE BlockAction
HTML.Tag.TD BlockAction
HTML.Tag.TEXTAREA FormAction
HTML.Tag.TH BlockAction
HTML.Tag.TITLE TitleAction
HTML.Tag.TR BlockAction
HTML.Tag.TT CharacterAction
HTML.Tag.U CharacterAction
HTML.Tag.UL BlockAction
HTML.Tag.VAR CharacterAction

Once </html> is encountered, the Actions are no longer notified.

  • Field Details

  • Constructor Details

    • HTMLReader

      public HTMLReader(int offset)
      Constructs an HTMLReader using default pop and push depth and no tag to insert.
      Parameters:
      offset - the starting offset

    • HTMLReader

      public HTMLReader(int offset, int popDepth, int pushDepth, HTML.Tag insertTag)
      Constructs an HTMLReader.
      Parameters:
      offset - the starting offset
      popDepth - how many parents to ascend before insert new element
      pushDepth - how many parents to descend (relative to popDepth) before inserting
      insertTag - a tag to insert (may be null)

  • Method Details

    • flush

      public void flush() throws BadLocationException
      The last method called on the reader. It allows any pending changes to be flushed into the document. Since this is currently loading synchronously, the entire set of changes are pushed in at this point.
      Overrides:
      flush in class HTMLEditorKit.ParserCallback
      Throws:
      BadLocationException - if the given position does not represent a valid location in the associated document.

    • handleText

      public void handleText(char[] data, int pos)
      Called by the parser to indicate a block of text was encountered.
      Overrides:
      handleText in class HTMLEditorKit.ParserCallback
      Parameters:
      data - a data
      pos - a position

    • handleStartTag

      public void handleStartTag(HTML.Tag t, MutableAttributeSet a, int pos)
      Callback from the parser. Route to the appropriate handler for the tag.
      Overrides:
      handleStartTag in class HTMLEditorKit.ParserCallback
      Parameters:
      t - an HTML tag
      a - a set of attributes
      pos - a position

    • handleEndTag

      public void handleEndTag(HTML.Tag t, int pos)
      Callback from the parser. Route to the appropriate handler for the tag.
      Overrides:
      handleEndTag in class HTMLEditorKit.ParserCallback
      Parameters:
      t - an HTML tag
      pos - a position

    • handleSimpleTag

      public void handleSimpleTag(HTML.Tag t, MutableAttributeSet a, int pos)
      Callback from the parser. Route to the appropriate handler for the tag.
      Overrides:
      handleSimpleTag in class HTMLEditorKit.ParserCallback
      Parameters:
      t - an HTML tag
      a - a set of attributes
      pos - a position

    • handleEndOfLineString

      public void handleEndOfLineString(String eol)
      This is invoked after the stream has been parsed, but before flush. eol will be one of \n, \r or \r\n, which ever is encountered the most in parsing the stream.
      Overrides:
      handleEndOfLineString in class HTMLEditorKit.ParserCallback
      Parameters:
      eol - value of eol
      Since:
      1.3

    • registerTag

      protected void registerTag(HTML.Tag t, HTMLDocument.HTMLReader.TagAction a)
      Registers a handler for the given tag. By default all of the well-known tags will have been registered. This can be used to change the handling of a particular tag or to add support for custom tags.
      Parameters:
      t - an HTML tag
      a - tag action handler

    • pushCharacterStyle

      protected void pushCharacterStyle()
      Pushes the current character style on a stack in preparation for forming a new nested character style.

    • popCharacterStyle

      protected void popCharacterStyle()
      Pops a previously pushed character style off the stack to return to a previous style.

    • textAreaContent

      protected void textAreaContent(char[] data)
      Adds the given content to the textarea document. This method gets called when we are in a textarea context. Therefore all text that is seen belongs to the text area and is hence added to the TextAreaDocument associated with the text area.
      Parameters:
      data - the given content

    • preContent

      protected void preContent(char[] data)
      Adds the given content that was encountered in a PRE element. This synthesizes lines to hold the runs of text, and makes calls to addContent to actually add the text.
      Parameters:
      data - the given content

    • blockOpen

      protected void blockOpen(HTML.Tag t, MutableAttributeSet attr)
      Adds an instruction to the parse buffer to create a block element with the given attributes.
      Parameters:
      t - an HTML tag
      attr - the attribute set

    • blockClose

      protected void blockClose(HTML.Tag t)
      Adds an instruction to the parse buffer to close out a block element of the given type.
      Parameters:
      t - the HTML tag

    • addContent

      protected void addContent(char[] data, int offs, int length)
      Adds some text with the current character attributes.
      Parameters:
      data - the content to add
      offs - the initial offset
      length - the length

    • addContent

      protected void addContent(char[] data, int offs, int length, boolean generateImpliedPIfNecessary)
      Adds some text with the current character attributes.
      Parameters:
      data - the content to add
      offs - the initial offset
      length - the length
      generateImpliedPIfNecessary - whether to generate implied paragraphs

    • addSpecialElement

      protected void addSpecialElement(HTML.Tag t, MutableAttributeSet a)
      Adds content that is basically specified entirely in the attribute set.
      Parameters:
      t - an HTML tag
      a - the attribute set