Supermarket operation support system - Software Development Case Studies in Java - page 377

import java.io.OutputStream;
public class SocketProxy
implements MarketProxy {
// the socket and the associated in and out streams
private Socket socket;
private InputStream in;
private OutputStream out;
// the name of the host where the market server runs
private String host;
public SocketProxy(String host){
this .host # host;
}
// send a synchronous message to the market
// server and returns the reply
private String sendMessage(String request)
throws Exception {
out.write((request ! "\n").getBytes());
out.flush();
byte [] buffer # new byte[1024];
int en;
len # in.read(buffer);
String reply # new String(buffer,0,len);
return reply;
}
// connect to the market server providing the employee
// code and pwd the server authenticates the employee
public String connect( long employee, String password)
throws Exception{
socket # new Socket(host,Const.SERVER_PORT);
in # socket.getInputStream();
out # socket.getOutputStream();
String reply # sendMessage(Const.AUTHENTICATE ! " " !
employee ! " " ! password);
if (reply.startsWith(Const.OK)){
return reply.substring(Const.OK.length());
} else {
return null ;
}
}
// return the name of a product given the code
public String getName( long item) throws Exception {
String reply # sendMessage(Const.GET_NAME ! " "
! item);
if (reply.startsWith(Const.OK)){
return reply.substring(Const.OK.length());
} else {