org.apache.commons.net.io
Class DotTerminatedMessageReader

java.lang.Object
  java.io.Reader
      java.io.BufferedReader
          org.apache.commons.net.io.DotTerminatedMessageReader

All Implemented Interfaces:

Closeable, Readable

public final class DotTerminatedMessageReader
extends BufferedReader

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, and ensures you cannot read past the end of the message.

Note: versions since 3.0 extend BufferedReader rather than Reader, and no longer change the CRLF into the local EOL. Also only DOT CR LF acts as EOF.

Version:

$Id: DotTerminatedMessageReader.java 1301276 2012-03-15 23:51:31Z sebb $

Field Summary

Fields inherited from class java.io.Reader

lock

Constructor Summary

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

Method Summary

void	close() Closes the message for reading.
int	read() Reads and returns the next character in the message.
int	read(char[] buffer) Reads the next characters from the message into an array and returns the number of characters read.
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.
String	readLine() Read a line of text.

Methods inherited from class java.io.BufferedReader

mark, markSupported, ready, reset, skip

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

Constructor Detail

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 Detail

read

public 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.

Overrides:

read in class BufferedReader

Returns:

The next character in the message. Returns -1 if the end of the message has been reached.

Throws:

IOException - If an error occurs while reading the underlying stream.

read

public 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.

Overrides:

read in class Reader

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.

Throws:

IOException - If an error occurs in reading the underlying stream.

read

public 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.

Overrides:

read in class BufferedReader

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.

Throws:

IOException - If an error occurs in reading the underlying stream.

close

public 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.

Specified by:

close in interface Closeable

Overrides:

close in class BufferedReader

Throws:

IOException - If an error occurs while reading the underlying stream.

readLine

public String readLine()
                throws IOException

Read a line of text. A line is considered to be terminated by carriage return followed immediately by a linefeed. This contrasts with BufferedReader which also allows other combinations.

Overrides:

readLine in class BufferedReader

Throws:

IOException

Since:

3.0