org.htmlparser.lexer
Class Page

java.lang.Object
  org.htmlparser.lexer.Page

All Implemented Interfaces:

Serializable

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).

See Also:

Serialized Form

Field Summary

static String	DEFAULT_CHARSET The default charset.
static String	DEFAULT_CONTENT_TYPE The default content type.
static char	EOF Character value when the page is exhausted.
protected String	mBaseUrl The base URL for this page.
protected URLConnection	mConnection The connection this page is coming from or null.
protected static ConnectionManager	mConnectionManager Connection control (proxy, cookies, authorization).
protected PageIndex	mIndex Character positions of the first character in each line.
protected Source	mSource The source of characters.
protected String	mUrl The URL this page is coming from.

Constructor Summary

Page()
Construct an empty page.

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

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

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

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

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

Method Summary

void	close() Close the page by destroying the source of characters.
int	column(Cursor cursor) Get the column number for a cursor.
int	column(int position) Get the column number for a cursor.
URL	constructUrl(String link, String base) Build a URL from the link and base provided using non-strict rules.
URL	constructUrl(String link, String base, boolean strict) Build a URL from the link and base provided.
protected void	finalize() Clean up this page, releasing resources.
static String	findCharset(String name, String fallback) Lookup a character set name.
String	getAbsoluteURL(String link) Create an absolute URL from a relative link.
String	getAbsoluteURL(String link, boolean strict) Create an absolute URL from a relative link.
String	getBaseUrl() Gets the baseUrl.
char	getCharacter(Cursor cursor) Read the character at the given cursor position.
String	getCharset(String content) Get a CharacterSet name corresponding to a charset parameter.
URLConnection	getConnection() Get the connection, if any.
static ConnectionManager	getConnectionManager() Get the connection manager all Parsers use.
String	getContentType() Try and extract the content type from the HTTP header.
String	getEncoding() Get the current encoding being used.
String	getLine(Cursor cursor) Get the text line the position of the cursor lies on.
String	getLine(int position) Get the text line the position of the cursor lies on.
Source	getSource() Get the source this page is reading from.
String	getText() Get all text read so far from the source.
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.
String	getText(int start, int end) Get the text identified by the given limits.
void	getText(StringBuffer buffer) Put all text read so far from the source into the given buffer.
void	getText(StringBuffer buffer, int start, int end) Put the text identified by the given limits into the given buffer.
String	getUrl() Get the URL for this page.
void	reset() Reset the page by resetting the source of characters.
int	row(Cursor cursor) Get the line number for a cursor.
int	row(int position) Get the line number for a cursor.
void	setBaseUrl(String url) Sets the baseUrl.
void	setConnection(URLConnection connection) Set the URLConnection to be used by this page.
static void	setConnectionManager(ConnectionManager manager) Set the connection manager to use.
void	setEncoding(String character_set) Begins reading from the source with the given character set.
void	setUrl(String url) Set the URL for this page.
String	toString() Display some of this page as a string.
void	ungetCharacter(Cursor cursor) Return a character.

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

DEFAULT_CHARSET

public static final String DEFAULT_CHARSET

The default charset. This should be "ISO-8859-1", see RFC 2616 (http://www.ietf.org/rfc/rfc2616.txt?number=2616) section 3.7.1

Another alias is "8859_1".

See Also:

Constant Field Values

DEFAULT_CONTENT_TYPE

public static final String DEFAULT_CONTENT_TYPE

The default content type. In the absence of alternate information, assume html content ("text/html").

See Also:

Constant Field Values

EOF

public static final char EOF

Character value when the page is exhausted. Has a value of 65535.

See Also:

Constant Field Values

mUrl

protected String mUrl

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

mBaseUrl

protected String mBaseUrl

The base URL for this page.

mSource

protected Source mSource

The source of characters.

mIndex

protected PageIndex mIndex

Character positions of the first character in each line.

mConnection

protected transient URLConnection mConnection

The connection this page is coming from or null.

mConnectionManager

protected static ConnectionManager mConnectionManager

Connection control (proxy, cookies, authorization).

Constructor Detail

Page

public Page()

Construct an empty page.

Page

public Page(URLConnection connection)
     throws ParserException

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)
     throws UnsupportedEncodingException

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 getEncoding(). 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

getConnectionManager

public static ConnectionManager getConnectionManager()

Get the connection manager all Parsers use.

Returns:

The connection manager.

setConnectionManager

public static void setConnectionManager(ConnectionManager manager)

Set the connection manager to use.

Parameters:

manager - The new connection manager.

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:

findCharset(java.lang.String, java.lang.String), DEFAULT_CHARSET

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.

reset

public void reset()

Reset the page by resetting the source of characters.

close

public void close()
           throws IOException

Close the page by destroying the source of characters.

Throws:

IOException - If destroying the source encounters an error.

finalize

protected void finalize()
                 throws Throwable

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

Overrides:

finalize in class Object

Throws:

Throwable - if close() throws an IOException.

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.

setConnection

public void setConnection(URLConnection connection)
                   throws ParserException

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.

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.

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.

getBaseUrl

public String getBaseUrl()

Gets the baseUrl.

Returns:

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

setBaseUrl

public void setBaseUrl(String url)

Sets the baseUrl.

Parameters:

url - The base url for this page.

getSource

public Source getSource()

Get the source this page is reading from.

Returns:

The current source.

getContentType

public String getContentType()

Try and extract the content type from the HTTP header.

Returns:

The content type.

getCharacter

public char getCharacter(Cursor cursor)
                  throws ParserException

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)

ungetCharacter

public void ungetCharacter(Cursor cursor)
                    throws ParserException

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.

getEncoding

public String getEncoding()

Get the current encoding being used.

Returns:

The encoding used to convert characters.

setEncoding

public void setEncoding(String character_set)
                 throws ParserException

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.

constructUrl

public URL constructUrl(String link,
                        String base)
                 throws MalformedURLException

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:

constructUrl(String, String, boolean)

constructUrl

public URL constructUrl(String link,
                        String base,
                        boolean strict)
                 throws MalformedURLException

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.

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.

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.

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.

getText

public String getText(int start,
                      int end)
               throws IllegalArgumentException

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:

getText(StringBuffer, int, int)

getText

public void getText(StringBuffer buffer,
                    int start,
                    int end)
             throws IllegalArgumentException

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(StringBuffer)

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:

getText(StringBuffer,int,int)

getText

public void getText(char[] array,
                    int offset,
                    int start,
                    int end)
             throws IllegalArgumentException

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).

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.

toString

public String toString()

Display some of this page as a string.

Overrides:

toString in class Object

Returns:

The last few characters the source read in.