org.htmlparser.lexer
Class Source

java.lang.Object
  java.io.Reader
      org.htmlparser.lexer.Source

All Implemented Interfaces:

Closeable, Serializable, Readable

Direct Known Subclasses:

InputStreamSource, StringSource

public abstract class Source
extends Reader
implements Serializable

A buffered source of characters. A Source is very similar to a Reader, like:

 new InputStreamReader (connection.getInputStream (), charset)
 

It differs from the above, in three ways:

• the fetching of bytes may be asynchronous
• the character set may be changed, which resets the input stream
• characters may be requested more than once, so in general they will be buffered

See Also:

Serialized Form

Field Summary

static int

EOF Return value when the source is exhausted.

Fields inherited from class java.io.Reader

lock

Constructor Summary

Source()

Method Summary

abstract int	available() Get the number of available characters.
abstract void	close() Does nothing.
abstract void	destroy() Close the source.
abstract char	getCharacter(int offset) Retrieve a character again.
abstract void	getCharacters(char[] array, int offset, int start, int end) Retrieve characters again.
abstract void	getCharacters(StringBuffer buffer, int offset, int length) Append characters already read into a StringBuffer.
abstract String	getEncoding() Get the encoding being used to convert characters.
abstract String	getString(int offset, int length) Retrieve a string comprised of characters already read.
abstract void	mark(int readAheadLimit) Mark the present position.
abstract boolean	markSupported() Tell whether this source supports the mark() operation.
abstract int	offset() Get the position (in characters).
abstract int	read() Read a single character.
abstract int	read(char[] cbuf) Read characters into an array.
abstract int	read(char[] cbuf, int off, int len) Read characters into a portion of an array.
abstract boolean	ready() Tell whether this source is ready to be read.
abstract void	reset() Reset the source.
abstract void	setEncoding(String character_set) Set the encoding to the given character set.
abstract long	skip(long n) Skip characters.
abstract void	unread() Undo the read of a single character.

Methods inherited from class java.io.Reader

read

Methods inherited from class java.lang.Object

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

Field Detail

EOF

public static final int EOF

Return value when the source is exhausted. Has a value of -1.

See Also:

Constant Field Values

Constructor Detail

Source

public Source()

Method Detail

getEncoding

public abstract String getEncoding()

Get the encoding being used to convert characters.

Returns:

The current encoding.

setEncoding

public abstract void setEncoding(String character_set)
                          throws ParserException

Set the encoding to 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 source will have been decoded using the given character set.

If characters have already been consumed from this source, it is expected that an exception will be thrown if the characters read so far would be different if the encoding being set was used from the start.

Parameters:

character_set - The character set to use to convert 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 character set is not recognized.

close

public abstract void close()
                    throws IOException

Does nothing. It's supposed to close the source, but use destroy() instead.

Specified by:

close in interface Closeable

Specified by:

close in class Reader

Throws:

IOException - not used

See Also:

destroy()

read

public abstract int read()
                  throws IOException

Read a single character. This method will block until a character is available, an I/O error occurs, or the source is exhausted.

Overrides:

read in class Reader

Returns:

The character read, as an integer in the range 0 to 65535 (0x00-0xffff), or EOF if the source is exhausted.

Throws:

IOException - If an I/O error occurs.

read

public abstract int read(char[] cbuf,
                         int off,
                         int len)
                  throws IOException

Read characters into a portion of an array. This method will block until some input is available, an I/O error occurs, or the source is exhausted.

Specified by:

read in class Reader

Parameters:

cbuf - Destination buffer

off - Offset at which to start storing characters

len - Maximum number of characters to read

Returns:

The number of characters read, or EOF if the source is exhausted.

Throws:

IOException - If an I/O error occurs.

read

public abstract int read(char[] cbuf)
                  throws IOException

Read characters into an array. This method will block until some input is available, an I/O error occurs, or the source is exhausted.

Overrides:

read in class Reader

Parameters:

cbuf - Destination buffer.

Returns:

The number of characters read, or EOF if the source is exhausted.

Throws:

IOException - If an I/O error occurs.

ready

public abstract boolean ready()
                       throws IOException

Tell whether this source is ready to be read.

Overrides:

ready in class Reader

Returns:

true if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.

Throws:

IOException - If an I/O error occurs.

reset

public abstract void reset()

Reset the source. Repositions the read point to begin at zero.

Overrides:

reset in class Reader

markSupported

public abstract boolean markSupported()

Tell whether this source supports the mark() operation.

Overrides:

markSupported in class Reader

Returns:

true if and only if this source supports the mark operation.

mark

public abstract void mark(int readAheadLimit)
                   throws IOException

Mark the present position. Subsequent calls to reset() will attempt to reposition the source to this point. Not all sources support the mark() operation.

Overrides:

mark in class Reader

Parameters:

readAheadLimit - The minimum number of characters that can be read before this mark becomes invalid.

Throws:

IOException - If an I/O error occurs.

skip

public abstract long skip(long n)
                   throws IOException

Skip characters. This method will block until some characters are available, an I/O error occurs, or the source is exhausted. Note: n is treated as an int

Overrides:

skip in class Reader

Parameters:

n - The number of characters to skip.

Returns:

The number of characters actually skipped

Throws:

IOException - If an I/O error occurs.

unread

public abstract void unread()
                     throws IOException

Undo the read of a single character.

Throws:

IOException - If the source is closed or no characters have been read.

getCharacter

public abstract char getCharacter(int offset)
                           throws IOException

Retrieve a character again.

Parameters:

offset - The offset of the character.

Returns:

The character at offset.

Throws:

IOException - If the source is closed or the offset is beyond offset().

getCharacters

public abstract void getCharacters(char[] array,
                                   int offset,
                                   int start,
                                   int end)
                            throws IOException

Retrieve characters again.

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:

IOException - If the source is closed or the start or end is beyond offset().

getString

public abstract String getString(int offset,
                                 int length)
                          throws IOException

Retrieve a string comprised of characters already read.

Parameters:

offset - The offset of the first character.

length - The number of characters to retrieve.

Returns:

A string containing the length characters at offset.

Throws:

IOException - If the source is closed.

getCharacters

public abstract void getCharacters(StringBuffer buffer,
                                   int offset,
                                   int length)
                            throws IOException

Append characters already read into a StringBuffer.

Parameters:

buffer - The buffer to append to.

offset - The offset of the first character.

length - The number of characters to retrieve.

Throws:

IOException - If the source is closed or the offset or (offset + length) is beyond offset().

destroy

public abstract void destroy()
                      throws IOException

Close the source. Once a source has been closed, further read, ready, mark, reset, skip, unread, getCharacter or getString invocations will throw an IOException. Closing a previously-closed source, however, has no effect.

Throws:

IOException - If an I/O error occurs.

offset

public abstract int offset()

Get the position (in characters).

Returns:

The number of characters that have already been read, or EOF if the source is closed.

available

public abstract int available()

Get the number of available characters.

Returns:

The number of characters that can be read without blocking.