Java Reference
In-Depth Information
2.4 Program
Echo
is similar to program
TCPEchoClient
from Sect.
2.2.1
, but has a
GUI front-end similar to that of program
GetRemoteTime
from Sect.
2.3
. It
provides an implementation of the
echo
protocol (on port 7). This implementa-
tion sends one-line messages to a server and uses the following components:
a text fi eld for input of messages (in addition to the text fi eld for input of host
name);
a text area for the (cumulative) echoed responses from the server;
a button to close the connection to the host.
Some of the code for this program has been provided for you in fi le
Echo.java
, a
printed copy of which appears at the end of this chapter. Examine this code and
make the necessary additions in the places indicated by the commented lines. When
you have completed the program, run it and supply the name of any convenient
server when prompted for a server name. If you don't have access to a convenient
server use
localhost
, having changed the port number of
TCPEchoServer
(Sect.
2.2.1
) to 7 and then started that program running.
//For use with exercise 2.2.
import java.io.*;
import java.net.*;
import java.util.*;
public class EmailServer
{
private static ServerSocket serverSocket;
private static fi nal int PORT = 1234;
private static fi nal String client1 = "Dave";
private static fi nal String client2 = "Karen";
private static fi nal int MAX_MESSAGES = 10;
private static String[] mailbox1 =
new String[MAX_MESSAGES];
private static String[] mailbox2 =
new String[MAX_MESSAGES];
private static int messagesInBox1 = 0;
private static int messagesInBox2 = 0;
public static void main(String[] args)
{
System.out.println("Opening connection…\n");
try
{
serverSocket = new ServerSocket(PORT);
}
catch(IOException ioEx)
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