org.htmlparser.lexer
Class InputStreamSource

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

All Implemented Interfaces:

Closeable, Serializable, Readable

public class InputStreamSource
extends Source

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

See Also:

Serialized Form

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

Fields inherited from class java.io.Reader

lock

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

read

Methods inherited from class java.lang.Object

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

Field Detail

BUFFER_SIZE

public static int BUFFER_SIZE

An initial buffer size. Has a default value of {16384}.

mStream

protected transient InputStream mStream

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

mEncoding

protected String mEncoding

The character set in use.

mReader

protected transient InputStreamReader mReader

The converter from bytes to characters.

mBuffer

protected char[] mBuffer

The characters read so far.

mLevel

protected int mLevel

The number of valid bytes in the buffer.

mOffset

protected int mOffset

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

mMark

protected int mMark

The bookmark.

Constructor Detail

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.

Throws:

UnsupportedEncodingException - If the default character set is unsupported.

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.

Throws:

UnsupportedEncodingException - If the character set is unsupported.

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.

Throws:

UnsupportedEncodingException - If the character set is unsupported.

Method Detail

getStream

public InputStream getStream()

Get the input stream being used.

Returns:

The current input stream.

getEncoding

public String getEncoding()

Get the encoding being used to convert characters.

Specified by:

getEncoding in class Source

Returns:

The current encoding.

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.

Specified by:

setEncoding in class 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.

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.

Throws:

IOException - If the underlying reader read() throws one.

close

public 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 Source

Throws:

IOException - not used

See Also:

destroy()

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.

Specified by:

read in class 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

Throws:

IOException - If an I/O error occurs.

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.

Specified by:

read in class 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

Throws:

IOException - If an I/O error occurs.

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.

Specified by:

read in class Source

Parameters:

cbuf - Destination buffer.

Returns:

The number of characters read, or EOF if the end of the stream has been reached.

Throws:

IOException - If an I/O error occurs.

reset

public void reset()
           throws IllegalStateException

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

Specified by:

reset in class Source

Throws:

IllegalStateException - If the source has been closed.

markSupported

public boolean markSupported()

Tell whether this source supports the mark() operation.

Specified by:

markSupported in class Source

Returns:

true.

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.

Specified by:

mark in class Source

Parameters:

readAheadLimit - Not used.

Throws:

IOException - If the source is closed.

ready

public boolean ready()
              throws IOException

Tell whether this source is ready to be read.

Specified by:

ready in class 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.

Throws:

IOException - If the source is closed.

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

Specified by:

skip in class Source

Parameters:

n - The number of characters to skip.

Returns:

The number of characters actually skipped

Throws:

IllegalArgumentException - If n is negative.

IOException - If an I/O error occurs.

unread

public void unread()
            throws IOException

Undo the read of a single character.

Specified by:

unread in class Source

Throws:

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

getCharacter

public char getCharacter(int offset)
                  throws IOException

Retrieve a character again.

Specified by:

getCharacter in class Source

Parameters:

offset - The offset of the character.

Returns:

The character at offset.

Throws:

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

getCharacters

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

Retrieve characters again.

Specified by:

getCharacters in class 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.

Throws:

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

getString

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

Retrieve a string.

Specified by:

getString in class 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.

Throws:

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

getCharacters

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

Append characters already read into a StringBuffer.

Specified by:

getCharacters in class Source

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

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.

Specified by:

destroy in class Source

Throws:

IOException - If an I/O error occurs

offset

public int offset()

Get the position (in characters).

Specified by:

offset in class Source

Returns:

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

available

public int available()

Get the number of available characters.

Specified by:

available in class Source

Returns:

The number of characters that can be read without blocking or zero if the source is closed.