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:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected DTD
    dtd
    The dtd.
    protected boolean
    strict
    This flag determines whether or not the Parser will be strict in enforcing SGML compatibility.

    Fields declared in interface DTDConstants

    ANY, CDATA, CONREF, CURRENT, DEFAULT, EMPTY, ENDTAG, ENTITIES, ENTITY, FIXED, GENERAL, ID, IDREF, IDREFS, IMPLIED, MD, MODEL, MS, NAME, NAMES, NMTOKEN, NMTOKENS, NOTATION, NUMBER, NUMBERS, NUTOKEN, NUTOKENS, PARAMETER, PI, PUBLIC, RCDATA, REQUIRED, SDATA, STARTTAG, SYSTEM
    Modifier and Type
    Field
    Description
    static final int
    ANY
    The DTD constant corresponds to ANY
    static final int
    CDATA
    The DTD constant corresponds to CDATA
    static final int
    CONREF
    The DTD constant corresponds to CONREF
    static final int
    CURRENT
    The DTD constant corresponds to CURRENT
    static final int
    DEFAULT
    The DTD constant corresponds to DEFAULT
    static final int
    EMPTY
    The DTD constant corresponds to EMPTY
    static final int
    ENDTAG
    The DTD constant corresponds to ENDTAG
    static final int
    ENTITIES
    The DTD constant corresponds to ENTITIES
    static final int
    ENTITY
    The DTD constant corresponds to ENTITY
    static final int
    FIXED
    The DTD constant corresponds to FIXED
    static final int
    GENERAL
    The DTD constant corresponds to GENERAL
    static final int
    ID
    The DTD constant corresponds to ID
    static final int
    IDREF
    The DTD constant corresponds to IDREF
    static final int
    IDREFS
    The DTD constant corresponds to IDREFS
    static final int
    IMPLIED
    The DTD constant corresponds to IMPLIED
    static final int
    MD
    The DTD constant corresponds to MD
    static final int
    MODEL
    The DTD constant corresponds to MODEL
    static final int
    MS
    The DTD constant corresponds to MS
    static final int
    NAME
    The DTD constant corresponds to NAME
    static final int
    NAMES
    The DTD constant corresponds to NAMES
    static final int
    NMTOKEN
    The DTD constant corresponds to NMTOKEN
    static final int
    NMTOKENS
    The DTD constant corresponds to NMTOKENS
    static final int
    NOTATION
    The DTD constant corresponds to NOTATION
    static final int
    NUMBER
    The DTD constant corresponds to NUMBER
    static final int
    NUMBERS
    The DTD constant corresponds to NUMBERS
    static final int
    NUTOKEN
    The DTD constant corresponds to NUTOKEN
    static final int
    NUTOKENS
    The DTD constant corresponds to NUTOKENS
    static final int
    PARAMETER
    The DTD constant corresponds to PARAMETER
    static final int
    PI
    The DTD constant corresponds to PI
    static final int
    PUBLIC
    The DTD constant corresponds to PUBLIC
    static final int
    RCDATA
    The DTD constant corresponds to RCDATA
    static final int
    REQUIRED
    The DTD constant corresponds to REQUIRED
    static final int
    SDATA
    The DTD constant corresponds to SDATA
    static final int
    STARTTAG
    The DTD constant corresponds to STARTTAG
    static final int
    SYSTEM
    The DTD constant corresponds to SYSTEM

  • Constructor Summary

    Constructors
    Constructor
    Description
    Parser(DTD dtd)
    Creates parser with the specified dtd.

  • Method Summary

    Modifier and Type
    Method
    Description
    protected void
    endTag(boolean omitted)
    Handle an end tag.
    protected void
    error(String err)
    Invokes the error handler with the 1st, 2nd and 3rd error message argument "?".
    protected void
    error(String err, String arg1)
    Invokes the error handler with the 2nd and 3rd error message argument "?".
    protected void
    error(String err, String arg1, String arg2)
    Invokes the error handler with the 3rd error message argument "?".
    protected void
    error(String err, String arg1, String arg2, String arg3)
    Invokes the error handler.
    protected void
    flushAttributes()
    Removes the current attributes.
    protected SimpleAttributeSet
    getAttributes()
    Returns attributes for the current tag.
    protected int
    getCurrentLine()
    Returns the line number of the line currently being parsed.
    protected int
    getCurrentPos()
    Returns the current position.
    protected void
    handleComment(char[] text)
    Called when an HTML comment is encountered.
    protected void
    handleEmptyTag(TagElement tag)
    Called when an empty tag is encountered.
    protected void
    handleEndTag(TagElement tag)
    Called when an end tag is encountered.
    protected void
    handleEOFInComment()
    Called when the content terminates without closing the HTML comment.
    protected void
    handleError(int ln, String msg)
    An error has occurred.
    protected void
    handleStartTag(TagElement tag)
    Called when a start tag is encountered.
    protected void
    handleText(char[] text)
    Called when PCDATA is encountered.
    protected void
    handleTitle(char[] text)
    Called when an HTML title tag is encountered.
    protected TagElement
    makeTag(Element elem)
    Makes a TagElement.
    protected TagElement
    makeTag(Element elem, boolean fictional)
    Makes a TagElement.
    protected void
    markFirstTime(Element elem)
    Marks the first time a tag has been seen in a document
    void
    parse(Reader in)
    Parse an HTML stream, given a DTD.
    String
    parseDTDMarkup()
    Parses the Document Type Declaration markup declaration.
    protected boolean
    parseMarkupDeclarations(StringBuffer strBuff)
    Parse markup declarations.
    protected void
    startTag(TagElement tag)
    Handle a start tag.

    Methods declared in class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    Modifier and Type
    Method
    Description
    protected Object
    clone()
    Creates and returns a copy of this object.
    boolean
    equals(Object obj)
    Indicates whether some other object is "equal to" this one.
    protected void
    finalize()
    Deprecated, for removal: This API element is subject to removal in a future version.
    Finalization is deprecated and subject to removal in a future release.
    final Class<?>
    getClass()
    Returns the runtime class of this Object.
    int
    hashCode()
    Returns a hash code value for this object.
    final void
    notify()
    Wakes up a single thread that is waiting on this object's monitor.
    final void
    notifyAll()
    Wakes up all threads that are waiting on this object's monitor.
    String
    toString()
    Returns a string representation of the object.
    final void
    wait()
    Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
    final void
    wait(long timeoutMillis)
    Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
    final void
    wait(long timeoutMillis, int nanos)
    Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

  • 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.
      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