Package org.htmlparser.lexer
Class Source
- java.lang.Object
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- java.io.Reader
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- org.htmlparser.lexer.Source
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- All Implemented Interfaces:
java.io.Closeable
,java.io.Serializable
,java.lang.AutoCloseable
,java.lang.Readable
- Direct Known Subclasses:
InputStreamSource
,StringSource
public abstract class Source extends java.io.Reader implements java.io.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
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Field Summary
Fields Modifier and Type Field Description static int
EOF
Return value when the source is exhausted.
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Constructor Summary
Constructors Constructor Description Source()
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description 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(java.lang.StringBuffer buffer, int offset, int length)
Append characters already read into aStringBuffer
.abstract java.lang.String
getEncoding()
Get the encoding being used to convert characters.abstract java.lang.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(java.lang.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.
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Field Detail
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EOF
public static final int EOF
Return value when the source is exhausted. Has a value of -1.- See Also:
- Constant Field Values
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Method Detail
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getEncoding
public abstract java.lang.String getEncoding()
Get the encoding being used to convert characters.- Returns:
- The current encoding.
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setEncoding
public abstract void setEncoding(java.lang.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.
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close
public abstract void close() throws java.io.IOException
Does nothing. It's supposed to close the source, but usedestroy()
instead.- Specified by:
close
in interfacejava.lang.AutoCloseable
- Specified by:
close
in interfacejava.io.Closeable
- Specified by:
close
in classjava.io.Reader
- Throws:
java.io.IOException
- not used- See Also:
destroy()
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read
public abstract int read() throws java.io.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 classjava.io.Reader
- Returns:
- The character read, as an integer in the range 0 to 65535
(0x00-0xffff), or
EOF
if the source is exhausted. - Throws:
java.io.IOException
- If an I/O error occurs.
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read
public abstract int read(char[] cbuf, int off, int len) throws java.io.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 classjava.io.Reader
- Parameters:
cbuf
- Destination bufferoff
- Offset at which to start storing characterslen
- Maximum number of characters to read- Returns:
- The number of characters read, or
EOF
if the source is exhausted. - Throws:
java.io.IOException
- If an I/O error occurs.
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read
public abstract int read(char[] cbuf) throws java.io.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 classjava.io.Reader
- Parameters:
cbuf
- Destination buffer.- Returns:
- The number of characters read, or
EOF
if the source is exhausted. - Throws:
java.io.IOException
- If an I/O error occurs.
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ready
public abstract boolean ready() throws java.io.IOException
Tell whether this source is ready to be read.- Overrides:
ready
in classjava.io.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:
java.io.IOException
- If an I/O error occurs.
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reset
public abstract void reset()
Reset the source. Repositions the read point to begin at zero.- Overrides:
reset
in classjava.io.Reader
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markSupported
public abstract boolean markSupported()
Tell whether this source supports the mark() operation.- Overrides:
markSupported
in classjava.io.Reader
- Returns:
true
if and only if this source supports the mark operation.
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mark
public abstract void mark(int readAheadLimit) throws java.io.IOException
Mark the present position. Subsequent calls toreset()
will attempt to reposition the source to this point. Not all sources support the mark() operation.- Overrides:
mark
in classjava.io.Reader
- Parameters:
readAheadLimit
- The minimum number of characters that can be read before this mark becomes invalid.- Throws:
java.io.IOException
- If an I/O error occurs.
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skip
public abstract long skip(long n) throws java.io.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 classjava.io.Reader
- Parameters:
n
- The number of characters to skip.- Returns:
- The number of characters actually skipped
- Throws:
java.io.IOException
- If an I/O error occurs.
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unread
public abstract void unread() throws java.io.IOException
Undo the read of a single character.- Throws:
java.io.IOException
- If the source is closed or no characters have been read.
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getCharacter
public abstract char getCharacter(int offset) throws java.io.IOException
Retrieve a character again.- Parameters:
offset
- The offset of the character.- Returns:
- The character at
offset
. - Throws:
java.io.IOException
- If the source is closed or the offset is beyondoffset()
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getCharacters
public abstract void getCharacters(char[] array, int offset, int start, int end) throws java.io.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:
java.io.IOException
- If the source is closed or the start or end is beyondoffset()
.
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getString
public abstract java.lang.String getString(int offset, int length) throws java.io.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 atoffset
. - Throws:
java.io.IOException
- If the source is closed.
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getCharacters
public abstract void getCharacters(java.lang.StringBuffer buffer, int offset, int length) throws java.io.IOException
Append characters already read into aStringBuffer
.- Parameters:
buffer
- The buffer to append to.offset
- The offset of the first character.length
- The number of characters to retrieve.- Throws:
java.io.IOException
- If the source is closed or the offset or (offset + length) is beyondoffset()
.
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destroy
public abstract void destroy() throws java.io.IOException
Close the source. Once a source has been closed, furtherread
,ready
,mark
,reset
,skip
,unread
,getCharacter
orgetString
invocations will throw an IOException. Closing a previously-closed source, however, has no effect.- Throws:
java.io.IOException
- If an I/O error occurs.
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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.
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available
public abstract int available()
Get the number of available characters.- Returns:
- The number of characters that can be read without blocking.
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