org.apache.commons.net.io

Class DotTerminatedMessageReader


public final class DotTerminatedMessageReader
extends Reader

DotTerminatedMessageReader is a class used to read messages from a server that are terminated by a single dot followed by a <CR><LF> sequence and with double dots appearing at the begining of lines which do not signal end of message yet start with a dot. Various Internet protocols such as NNTP and POP3 produce messages of this type.

This class handles stripping of the duplicate period at the beginning of lines starting with a period, converts NETASCII newlines to the local line separator format, truncates the end of message indicator, and ensures you cannot read past the end of the message.

Constructor Summary

DotTerminatedMessageReader(Reader reader)
Creates a DotTerminatedMessageReader that wraps an existing Reader input source.

Method Summary

@Override
boolean ready()
Determines if the message is ready to be read.
@Override
int read()
Reads and returns the next character in the message.
@Override
int read(char[] buffer)
Reads the next characters from the message into an array and returns the number of characters read.
@Override
int read(char[] buffer, int offset, int length)
Reads the next characters from the message into an array and returns the number of characters read.
@Override
void close()
Closes the message for reading.

Constructor Details

DotTerminatedMessageReader

public DotTerminatedMessageReader(Reader reader)
Creates a DotTerminatedMessageReader that wraps an existing Reader input source.
Parameters:
reader - The Reader input source containing the message.

Method Details

boolean ready

public @Override boolean ready()
            throws IOException
Determines if the message is ready to be read.
Returns:
True if the message is ready to be read, false if not.

int read

public @Override int read()
            throws IOException
Reads and returns the next character in the message. If the end of the message has been reached, returns -1. Note that a call to this method may result in multiple reads from the underlying input stream to decode the message properly (removing doubled dots and so on). All of this is transparent to the programmer and is only mentioned for completeness.
Returns:
The next character in the message. Returns -1 if the end of the message has been reached.

int read

public @Override int read(char[] buffer)
            throws IOException
Reads the next characters from the message into an array and returns the number of characters read. Returns -1 if the end of the message has been reached.
Parameters:
buffer - The character array in which to store the characters.
Returns:
The number of characters read. Returns -1 if the end of the message has been reached.

int read

public @Override int read(char[] buffer,
                          int offset,
                          int length)
            throws IOException
Reads the next characters from the message into an array and returns the number of characters read. Returns -1 if the end of the message has been reached. The characters are stored in the array starting from the given offset and up to the length specified.
Parameters:
buffer - The character array in which to store the characters.
offset - The offset into the array at which to start storing characters.
length - The number of characters to read.
Returns:
The number of characters read. Returns -1 if the end of the message has been reached.

void close

public @Override void close()
            throws IOException
Closes the message for reading. This doesn't actually close the underlying stream. The underlying stream may still be used for communicating with the server and therefore is not closed.

If the end of the message has not yet been reached, this method will read the remainder of the message until it reaches the end, so that the underlying stream may continue to be used properly for communicating with the server. If you do not fully read a message, you MUST close it, otherwise your program will likely hang or behave improperly.