Sending and Receiving Messages - TCP/IP Sockets in Java Practical Guide for Programmers - page 46

1. nextToken() : lines 4-24
Read from input stream until delimiter or end-of-stream.
Test for end-of-stream: lines 8-10
If the input stream is already at end-of-stream, return null .
Create a buffer to hold the bytes of the token: line 12
We use a ByteArrayOutputStream to collect the data byte by byte. The ByteArray[Input|
Output]Stream classes allow a byte array to be handled like a stream of bytes.
Put the last byte read into the buffer : line 14
Get a byte array containing the input so far: line 15
It is very inecient to create a new byte array on each iteration, but it is simple.
Check whether the delimiter is a sux of the current token: lines 16-21
If so, create a new byte array containing the bytes read so far, minus the delimiter
sux, and return it.
Get next byte: line 22
Return the current token on end-of-stream: line 23

2. endswith() : lines 26-35
Compare lengths: lines 28-29
The candidate sequence must be at least as long as the delimiter to be a match.
Compare bytes, return false on any difference: lines 31-33
Compare the last delim.length bytes of the token to the delimiter.
If no difference, return true : line 34

3.4 Implementing Wire Formats in Java

To emphasize the fact that the same information can be represented “on the wire” in different
ways, we define an interface ItemQuoteEncoder , which has a single method that takes an
ItemQuote instance and converts it to a byte[ ] that can be written to an OutputStream or
encapsulated in a DatagramPacket .

ItemQuoteEncoder.java

0 public interface ItemQuoteEncoder {
1

byte[] encode(ItemQuote item) throws Exception;

2 }

ItemQuoteEncoder.java

The specification of the corresponding decoding functionality is given by the ItemQuot−
eDecoder interface, which has methods for parsing messages received via streams or in Data−