org.htmlparser.lexer

Class Page

public class Page extends Object implements Serializable

Represents the contents of an HTML page. Contains the source of characters and an index of positions of line separators (actually the first character position on the next line).
Field Summary
static StringDEFAULT_CHARSET
The default charset.
static StringDEFAULT_CONTENT_TYPE
The default content type.
static charEOF
Character value when the page is exhausted.
protected StringmBaseUrl
The base URL for this page.
protected URLConnectionmConnection
The connection this page is coming from or null.
protected static ConnectionManagermConnectionManager
Connection control (proxy, cookies, authorization).
protected PageIndexmIndex
Character positions of the first character in each line.
protected SourcemSource
The source of characters.
protected StringmUrl
The URL this page is coming from.
Constructor Summary
Page()
Construct an empty page.
Page(URLConnection connection)
Construct a page reading from a URL connection.
Page(InputStream stream, String charset)
Construct a page from a stream encoded with the given charset.
Page(String text, String charset)
Construct a page from the given string.
Page(String text)
Construct a page from the given string.
Page(Source source)
Construct a page from a source.
Method Summary
voidclose()
Close the page by destroying the source of characters.
intcolumn(Cursor cursor)
Get the column number for a cursor.
intcolumn(int position)
Get the column number for a cursor.
URLconstructUrl(String link, String base)
Build a URL from the link and base provided using non-strict rules.
URLconstructUrl(String link, String base, boolean strict)
Build a URL from the link and base provided.
protected voidfinalize()
Clean up this page, releasing resources.
static StringfindCharset(String name, String fallback)
Lookup a character set name.
StringgetAbsoluteURL(String link)
Create an absolute URL from a relative link.
StringgetAbsoluteURL(String link, boolean strict)
Create an absolute URL from a relative link.
StringgetBaseUrl()
Gets the baseUrl.
chargetCharacter(Cursor cursor)
Read the character at the given cursor position.
StringgetCharset(String content)
Get a CharacterSet name corresponding to a charset parameter.
URLConnectiongetConnection()
Get the connection, if any.
static ConnectionManagergetConnectionManager()
Get the connection manager all Parsers use.
StringgetContentType()
Try and extract the content type from the HTTP header.
StringgetEncoding()
Get the current encoding being used.
StringgetLine(Cursor cursor)
Get the text line the position of the cursor lies on.
StringgetLine(int position)
Get the text line the position of the cursor lies on.
SourcegetSource()
Get the source this page is reading from.
StringgetText(int start, int end)
Get the text identified by the given limits.
voidgetText(StringBuffer buffer, int start, int end)
Put the text identified by the given limits into the given buffer.
StringgetText()
Get all text read so far from the source.
voidgetText(StringBuffer buffer)
Put all text read so far from the source into the given buffer.
voidgetText(char[] array, int offset, int start, int end)
Put the text identified by the given limits into the given array at the specified offset.
StringgetUrl()
Get the URL for this page.
voidreset()
Reset the page by resetting the source of characters.
introw(Cursor cursor)
Get the line number for a cursor.
introw(int position)
Get the line number for a cursor.
voidsetBaseUrl(String url)
Sets the baseUrl.
voidsetConnection(URLConnection connection)
Set the URLConnection to be used by this page.
static voidsetConnectionManager(ConnectionManager manager)
Set the connection manager to use.
voidsetEncoding(String character_set)
Begins reading from the source with the given character set.
voidsetUrl(String url)
Set the URL for this page.
StringtoString()
Display some of this page as a string.
voidungetCharacter(Cursor cursor)
Return a character.

Field Detail

DEFAULT_CHARSET

public static final String DEFAULT_CHARSET
The default charset. This should be {@value }, see RFC 2616 (http://www.ietf.org/rfc/rfc2616.txt?number=2616) section 3.7.1

Another alias is "8859_1".

DEFAULT_CONTENT_TYPE

public static final String DEFAULT_CONTENT_TYPE
The default content type. In the absence of alternate information, assume html content ({@value }).

EOF

public static final char EOF
Character value when the page is exhausted. Has a value of {@value }.

mBaseUrl

protected String mBaseUrl
The base URL for this page.

mConnection

protected transient URLConnection mConnection
The connection this page is coming from or null.

mConnectionManager

protected static ConnectionManager mConnectionManager
Connection control (proxy, cookies, authorization).

mIndex

protected PageIndex mIndex
Character positions of the first character in each line.

mSource

protected Source mSource
The source of characters.

mUrl

protected String mUrl
The URL this page is coming from. Cached value of getConnection().toExternalForm() or setUrl().

Constructor Detail

Page

public Page()
Construct an empty page.

Page

public Page(URLConnection connection)
Construct a page reading from a URL connection.

Parameters: connection A fully conditioned connection. The connect() method will be called so it need not be connected yet.

Throws: ParserException An exception object wrapping a number of possible error conditions, some of which are outlined below.

  • IOException If an i/o exception occurs creating the source.
  • UnsupportedEncodingException if the character set specified in the HTTP header is not supported.
  • Page

    public Page(InputStream stream, String charset)
    Construct a page from a stream encoded with the given charset.

    Parameters: stream The source of bytes. charset The encoding used. If null, defaults to the DEFAULT_CHARSET.

    Throws: UnsupportedEncodingException If the given charset is not supported.

    Page

    public Page(String text, String charset)
    Construct a page from the given string.

    Parameters: text The HTML text. charset Optional. The character set encoding that will be reported by Page. If charset is null the default character set is used.

    Page

    public Page(String text)
    Construct a page from the given string. The page will report that it is using an encoding of DEFAULT_CHARSET.

    Parameters: text The HTML text.

    Page

    public Page(Source source)
    Construct a page from a source.

    Parameters: source The source of characters.

    Method Detail

    close

    public void close()
    Close the page by destroying the source of characters.

    Throws: IOException If destroying the source encounters an error.

    column

    public int column(Cursor cursor)
    Get the column number for a cursor.

    Parameters: cursor The character offset into the page.

    Returns: The character offset into the line this cursor is on.

    column

    public int column(int position)
    Get the column number for a cursor.

    Parameters: position The character offset into the page.

    Returns: The character offset into the line this cursor is on.

    constructUrl

    public URL constructUrl(String link, String base)
    Build a URL from the link and base provided using non-strict rules.

    Parameters: link The (relative) URI. base The base URL of the page, either from the <BASE> tag or, if none, the URL the page is being fetched from.

    Returns: An absolute URL.

    Throws: MalformedURLException If creating the URL fails.

    See Also: Page

    constructUrl

    public URL constructUrl(String link, String base, boolean strict)
    Build a URL from the link and base provided.

    Parameters: link The (relative) URI. base The base URL of the page, either from the <BASE> tag or, if none, the URL the page is being fetched from. strict If true a link starting with '?' is handled according to RFC 2396, otherwise the common interpretation of a query appended to the base is used instead.

    Returns: An absolute URL.

    Throws: MalformedURLException If creating the URL fails.

    finalize

    protected void finalize()
    Clean up this page, releasing resources. Calls close().

    Throws: Throwable if close() throws an IOException.

    findCharset

    public static String findCharset(String name, String fallback)
    Lookup a character set name. Vacuous for JVM's without java.nio.charset. This uses reflection so the code will still run under prior JDK's but in that case the default is always returned.

    Parameters: name The name to look up. One of the aliases for a character set. fallback The name to return if the lookup fails.

    Returns: The character set name.

    getAbsoluteURL

    public String getAbsoluteURL(String link)
    Create an absolute URL from a relative link.

    Parameters: link The reslative portion of a URL.

    Returns: The fully qualified URL or the original link if it was absolute already or a failure occured.

    getAbsoluteURL

    public String getAbsoluteURL(String link, boolean strict)
    Create an absolute URL from a relative link.

    Parameters: link The reslative portion of a URL. strict If true a link starting with '?' is handled according to RFC 2396, otherwise the common interpretation of a query appended to the base is used instead.

    Returns: The fully qualified URL or the original link if it was absolute already or a failure occured.

    getBaseUrl

    public String getBaseUrl()
    Gets the baseUrl.

    Returns: The base URL for this page, or null if not set.

    getCharacter

    public char getCharacter(Cursor cursor)
    Read the character at the given cursor position. The cursor position can be only behind or equal to the current source position. Returns end of lines (EOL) as \n, by converting \r and \r\n to \n, and updates the end-of-line index accordingly. Advances the cursor position by one (or two in the \r\n case).

    Parameters: cursor The position to read at.

    Returns: The character at that position, and modifies the cursor to prepare for the next read. If the source is exhausted a zero is returned.

    Throws: ParserException If an IOException on the underlying source occurs, or an attempt is made to read characters in the future (the cursor position is ahead of the underlying stream)

    getCharset

    public String getCharset(String content)
    Get a CharacterSet name corresponding to a charset parameter.

    Parameters: content A text line of the form:

     text/html; charset=Shift_JIS
     
    which is applicable both to the HTTP header field Content-Type and the meta tag http-equiv="Content-Type". Note this method also handles non-compliant quoted charset directives such as:
     text/html; charset="UTF-8"
     
    and
     text/html; charset='UTF-8'
     

    Returns: The character set name to use when reading the input stream. For JDKs that have the Charset class this is qualified by passing the name to findCharset() to render it into canonical form. If the charset parameter is not found in the given string, the default character set is returned.

    See Also: Page DEFAULT_CHARSET

    getConnection

    public URLConnection getConnection()
    Get the connection, if any.

    Returns: The connection object for this page, or null if this page is built from a stream or a string.

    getConnectionManager

    public static ConnectionManager getConnectionManager()
    Get the connection manager all Parsers use.

    Returns: The connection manager.

    getContentType

    public String getContentType()
    Try and extract the content type from the HTTP header.

    Returns: The content type.

    getEncoding

    public String getEncoding()
    Get the current encoding being used.

    Returns: The encoding used to convert characters.

    getLine

    public String getLine(Cursor cursor)
    Get the text line the position of the cursor lies on.

    Parameters: cursor The position to calculate for.

    Returns: The contents of the URL or file corresponding to the line number containing the cursor position.

    getLine

    public String getLine(int position)
    Get the text line the position of the cursor lies on.

    Parameters: position The position to calculate for.

    Returns: The contents of the URL or file corresponding to the line number containg the cursor position.

    getSource

    public Source getSource()
    Get the source this page is reading from.

    Returns: The current source.

    getText

    public String getText(int start, int end)
    Get the text identified by the given limits.

    Parameters: start The starting position, zero based. end The ending position (exclusive, i.e. the character at the ending position is not included), zero based.

    Returns: The text from start to end.

    Throws: IllegalArgumentException If an attempt is made to get characters ahead of the current source offset (character position).

    See Also: Page

    getText

    public void getText(StringBuffer buffer, int start, int end)
    Put the text identified by the given limits into the given buffer.

    Parameters: buffer The accumulator for the characters. start The starting position, zero based. end The ending position (exclusive, i.e. the character at the ending position is not included), zero based.

    Throws: IllegalArgumentException If an attempt is made to get characters ahead of the current source offset (character position).

    getText

    public String getText()
    Get all text read so far from the source.

    Returns: The text from the source.

    See Also: getText

    getText

    public void getText(StringBuffer buffer)
    Put all text read so far from the source into the given buffer.

    Parameters: buffer The accumulator for the characters.

    See Also: Page

    getText

    public void getText(char[] array, int offset, int start, int end)
    Put the text identified by the given limits into the given array at the specified offset.

    Parameters: array The array of characters. offset The starting position in the array where characters are to be placed. start The starting position, zero based. end The ending position (exclusive, i.e. the character at the ending position is not included), zero based.

    Throws: IllegalArgumentException If an attempt is made to get characters ahead of the current source offset (character position).

    getUrl

    public String getUrl()
    Get the URL for this page. This is only available if the page has a connection (getConnection() returns non-null), or the document base has been set via a call to setUrl().

    Returns: The url for the connection, or null if there is no conenction or the document base has not been set.

    reset

    public void reset()
    Reset the page by resetting the source of characters.

    row

    public int row(Cursor cursor)
    Get the line number for a cursor.

    Parameters: cursor The character offset into the page.

    Returns: The line number the character is in.

    row

    public int row(int position)
    Get the line number for a cursor.

    Parameters: position The character offset into the page.

    Returns: The line number the character is in.

    setBaseUrl

    public void setBaseUrl(String url)
    Sets the baseUrl.

    Parameters: url The base url for this page.

    setConnection

    public void setConnection(URLConnection connection)
    Set the URLConnection to be used by this page. Starts reading from the given connection. This also resets the current url.

    Parameters: connection The connection to use. It will be connected by this method.

    Throws: ParserException If the connect() method fails, or an I/O error occurs opening the input stream or the character set designated in the HTTP header is unsupported.

    setConnectionManager

    public static void setConnectionManager(ConnectionManager manager)
    Set the connection manager to use.

    Parameters: manager The new connection manager.

    setEncoding

    public void setEncoding(String character_set)
    Begins reading from the source with the given character set. If the current encoding is the same as the requested encoding, this method is a no-op. Otherwise any subsequent characters read from this page will have been decoded using the given character set.

    Some magic happens here to obtain this result if characters have already been consumed from this page. Since a Reader cannot be dynamically altered to use a different character set, the underlying stream is reset, a new Source is constructed and a comparison made of the characters read so far with the newly read characters up to the current position. If a difference is encountered, or some other problem occurs, an exception is thrown.

    Parameters: character_set The character set to use to convert bytes into characters.

    Throws: ParserException If a character mismatch occurs between characters already provided and those that would have been returned had the new character set been in effect from the beginning. An exception is also thrown if the underlying stream won't put up with these shenanigans.

    setUrl

    public void setUrl(String url)
    Set the URL for this page. This doesn't affect the contents of the page, just the interpretation of relative links from this point forward.

    Parameters: url The new URL.

    toString

    public String toString()
    Display some of this page as a string.

    Returns: The last few characters the source read in.

    ungetCharacter

    public void ungetCharacter(Cursor cursor)
    Return a character. Handles end of lines (EOL) specially, retreating the cursor twice for the '\r\n' case. The cursor position is moved back by one (or two in the \r\n case).

    Parameters: cursor The position to 'unread' at.

    Throws: ParserException If an IOException on the underlying source occurs.

    HTML Parser is an open source library released under LGPL. SourceForge.net