org.htmlparser.lexer

Class InputStreamSource

Implemented Interfaces:
Serializable

public class InputStreamSource
extends Source

A source of characters based on an InputStream such as from a URLConnection.

Field Summary

static int
BUFFER_SIZE
An initial buffer size.
protected char[]
mBuffer
The characters read so far.
protected String
mEncoding
The character set in use.
protected int
mLevel
The number of valid bytes in the buffer.
protected int
mMark
The bookmark.
protected int
mOffset
The offset of the next byte returned by read().
protected InputStreamReader
mReader
The converter from bytes to characters.
protected InputStream
mStream
The stream of bytes.

Fields inherited from class org.htmlparser.lexer.Source

EOF

Constructor Summary

InputStreamSource(InputStream stream)
Create a source of characters using the default character set.
InputStreamSource(InputStream stream, String charset)
Create a source of characters.
InputStreamSource(InputStream stream, String charset, int size)
Create a source of characters.

Method Summary

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

Methods inherited from class org.htmlparser.lexer.Source

available, close, destroy, getCharacter, getCharacters, getCharacters, getEncoding, getString, mark, markSupported, offset, read, read, read, ready, reset, setEncoding, skip, unread

Field Details

BUFFER_SIZE

public static int BUFFER_SIZE
An initial buffer size. Has a default value of {16384}.

mBuffer

protected char[] mBuffer
The characters read so far.

mEncoding

protected String mEncoding
The character set in use.

mLevel

protected int mLevel
The number of valid bytes in the buffer.

mMark

protected int mMark
The bookmark.

mOffset

protected int mOffset
The offset of the next byte returned by read().

mReader

protected InputStreamReader mReader
The converter from bytes to characters.

mStream

protected InputStream mStream
The stream of bytes. Set to null when the source is closed.

Constructor Details

InputStreamSource

public InputStreamSource(InputStream stream)
            throws UnsupportedEncodingException
Create a source of characters using the default character set.
Parameters:
stream - The stream of bytes to use.

InputStreamSource

public InputStreamSource(InputStream stream,
                         String charset)
            throws UnsupportedEncodingException
Create a source of characters.
Parameters:
stream - The stream of bytes to use.
charset - The character set used in encoding the stream.

InputStreamSource

public InputStreamSource(InputStream stream,
                         String charset,
                         int size)
            throws UnsupportedEncodingException
Create a source of characters.
Parameters:
stream - The stream of bytes to use.
charset - The character set used in encoding the stream.
size - The initial character buffer size.

Method Details

available

public int available()
Get the number of available characters.
Overrides:
available in interface Source
Returns:
The number of characters that can be read without blocking or zero if the source is closed.

close

public void close()
            throws IOException
Does nothing. It's supposed to close the source, but use destroy() instead.
Overrides:
close in interface Source
See Also:
destroy()

destroy

public 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.
Overrides:
destroy in interface Source

fill

protected void fill(int min)
            throws IOException
Fetch more characters from the underlying reader. Has no effect if the underlying reader has been drained.
Parameters:
min - The minimum to read.

getCharacter

public char getCharacter(int offset)
            throws IOException
Retrieve a character again.
Overrides:
getCharacter in interface Source
Parameters:
offset - The offset of the character.
Returns:
The character at offset.

getCharacters

public void getCharacters(StringBuffer buffer,
                          int offset,
                          int length)
            throws IOException
Append characters already read into a StringBuffer.
Overrides:
getCharacters in interface Source
Parameters:
buffer - The buffer to append to.
offset - The offset of the first character.
length - The number of characters to retrieve.

getCharacters

public void getCharacters(char[] array,
                          int offset,
                          int start,
                          int end)
            throws IOException
Retrieve characters again.
Overrides:
getCharacters in interface Source
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 String getEncoding()
Get the encoding being used to convert characters.
Overrides:
getEncoding in interface Source
Returns:
The current encoding.

getStream

public InputStream getStream()
Get the input stream being used.
Returns:
The current input stream.

getString

public String getString(int offset,
                        int length)
            throws IOException
Retrieve a string.
Overrides:
getString in interface Source
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 void mark(int readAheadLimit)
            throws IOException
Mark the present position in the source. Subsequent calls to reset() will attempt to reposition the source to this point.
Overrides:
mark in interface Source
Parameters:
readAheadLimit - Not used.

markSupported

public boolean markSupported()
Tell whether this source supports the mark() operation.
Overrides:
markSupported in interface Source
Returns:
true.

offset

public int offset()
Get the position (in characters).
Overrides:
offset in interface Source
Returns:
The number of characters that have already been read, or EOF if the source is closed.

read

public int read()
            throws IOException
Read a single character. This method will block until a character is available, an I/O error occurs, or the end of the stream is reached.
Overrides:
read in interface Source
Returns:
The character read, as an integer in the range 0 to 65535 (0x00-0xffff), or EOF if the end of the stream has been reached

read

public 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 end of the stream is reached.
Overrides:
read in interface Source
Parameters:
cbuf - Destination buffer.
Returns:
The number of characters read, or EOF if the end of the stream has been reached.

read

public 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 end of the stream is reached.
Overrides:
read in interface Source
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 end of the stream has been reached

ready

public boolean ready()
            throws IOException
Tell whether this source is ready to be read.
Overrides:
ready in interface Source
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 void reset()
            throws IllegalStateException
Reset the source. Repositions the read point to begin at zero.
Overrides:
reset in interface Source

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 source. 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.

Overrides:
setEncoding in interface Source
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.

skip

public long skip(long n)
            throws IOException,
                   IllegalArgumentException
Skip characters. This method will block until some characters are available, an I/O error occurs, or the end of the stream is reached. Note: n is treated as an int
Overrides:
skip in interface Source
Parameters:
n - The number of characters to skip.
Returns:
The number of characters actually skipped

unread

public void unread()
            throws IOException
Undo the read of a single character.
Overrides:
unread in interface Source

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