java.io
public class LineNumberInputStream extends FilterInputStream
Deprecated: This class is deprecated in favor if
LineNumberReader because it operates on ASCII bytes
instead of an encoded character stream. This class is for backward
compatibility only and should not be used in new applications.
InputStream
except that it counts line numbers, and canonicalizes newline
characters. As data is read, whenever the byte sequences "\r",
"\n", or "\r\n" are encountered, the running line count is
incremeted by one. Additionally, the whatever line termination
sequence was encountered will be converted to a "\n" byte. Note
that this class numbers lines from 0. When the first line
terminator is encountered, the line number is incremented to 1, and
so on.
This class counts only line termination characters. If the last line read from the stream does not end in a line termination sequence, it will not be counted as a line.
Note that since this class operates as a filter on an underlying
stream, it has the same mark/reset functionality as the underlying
stream. The mark() and reset() methods
in this class handle line numbers correctly. Calling
reset() resets the line number to the point at which
mark() was called if the subordinate stream supports
that functionality.
| Constructor Summary | |
|---|---|
| LineNumberInputStream(InputStream in)
Create a new LineNumberInputStream that reads from the
specified subordinate InputStream
| |
| Method Summary | |
|---|---|
| int | available()
This method returns the number of bytes that can be read from the
stream before the stream can block. |
| int | getLineNumber()
This method returns the current line number
|
| void | mark(int readlimit)
This method marks a position in the input to which the stream can
be "reset" byte calling the reset() method. |
| int | read()
This method reads an unsigned byte from the input stream and returns it
as an int in the range of 0-255. |
| int | read(byte[] b, int off, int len)
This method reads bytes from a stream and stores them into a caller
supplied buffer. |
| void | reset()
This method resets a stream to the point where the
mark() method was called. |
| void | setLineNumber(int lineNumber)
This method sets the current line number to the specified value.
|
| long | skip(long n)
This method skips up to the requested number of bytes in the
input stream. |
LineNumberInputStream that reads from the
specified subordinate InputStream
Parameters: in The subordinate InputStream to read from
InputStream might return
only "\r\n" characters, which are replaced by a single "\n"
character by the read() method of this class. So
this method can only guarantee that in.available() /
2 bytes can actually be read before blocking. In
practice, considerably more bytes might be read before blocking
Note that the stream may not block if additional bytes beyond the count returned by this method are read.
Returns: The number of bytes that can be read before blocking could occur
Throws: IOException If an error occurs
Returns: The current line number
reset() method. The
parameter readlimit is the number of bytes that can
be read from the stream after setting the mark before the mark
becomes invalid. For example, if mark() is called
with a read limit of 10, then when 11 bytes of data are read from
the stream before the reset() method is called, then
the mark is invalid and the stream object instance is not
required to remember the mark.
In this class, this method will remember the current line number
as well as the current position in the stream. When the
reset() method is called, the line number will be
restored to the saved line number in addition to the stream
position.
This method only works if the subordinate stream supports mark/reset functionality.
Parameters: readlimit The number of bytes that can be read before the mark becomes invalid
Note that if a line termination sequence is encountered (ie, "\r", "\n", or "\r\n") then that line termination sequence is converted to a single "\n" value which is returned from this method. This means that it is possible this method reads two bytes from the subordinate stream instead of just one.
Note that this method will block until a byte of data is available to be read.
Returns: The byte read or -1 if end of stream
Throws: IOException If an error occurs
offset into
the buffer and attemps to read len bytes. This method can
return before reading the number of bytes requested. The actual number
of bytes read is returned as an int. A -1 is returned to indicated the
end of the stream.
This method will block until some data can be read.
Note that if a line termination sequence is encountered (ie, "\r", "\n", or "\r\n") then that line termination sequence is converted to a single "\n" value which is stored in the buffer. Only a single byte is counted towards the number of bytes read in this case.
Parameters: b The array into which the bytes read should be stored off The offset into the array to start storing bytes len The requested number of bytes to read
Returns: The actual number of bytes read, or -1 if end of stream
Throws: IOException If an error occurs.
mark() method was called. Any bytes that were read
after the mark point was set will be re-read during subsequent
reads.
In this class, this method will also restore the line number that was
current when the mark() method was called.
This method only works if the subordinate stream supports mark/reset functionality.
Throws: IOException If an error occurs
Parameters: lineNumber The new line number
Parameters: n requested number of bytes to skip.
Returns: The actual number of bytes skipped.
Throws: IOException If an error occurs.