org.htmlparser.lexer

Class Source

Implemented Interfaces:
Serializable
Known Direct 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:

Field Summary

static int
EOF
Return value when the source is exhausted.

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(StringBuffer buffer, int offset, int length)
Append characters already read into a StringBuffer.
abstract void
getCharacters(char[] array, int offset, int start, int end)
Retrieve characters again.
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.

Field Details

EOF

public static final int EOF
Return value when the source is exhausted. Has a value of .
Field Value:
-1

Method Details

available

public abstract int available()
Get the number of available characters.
Returns:
The number of characters that can be read without blocking.

close

public abstract void close()
            throws IOException
See Also:
destroy()

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.

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.

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.

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.

getEncoding

public abstract String getEncoding()
Get the encoding being used to convert characters.
Returns:
The current encoding.

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.

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

markSupported

public abstract boolean markSupported()
Tell whether this source supports the mark() operation.
Returns:
true if and only if this source supports the mark operation.

offset

public abstract int offset()
Get the position (in characters).

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.

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.
Parameters:
cbuf - Destination buffer.

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.
Parameters:
cbuf - Destination buffer
off - Offset at which to start storing characters
len - Maximum number of characters to read

ready

public abstract boolean ready()
            throws IOException
Tell whether this source is ready to be read.
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.

reset

public abstract void reset()
Reset the source. Repositions the read point to begin at zero.

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.

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
Parameters:
n - The number of characters to skip.
Returns:
The number of characters actually skipped

unread

public abstract void unread()
            throws IOException
Undo the read of a single character.

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