Mega Code Archive
Connects to a server at a specified host and port It reads text from the console and sends it to the server
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/*
* Copyright (c) 2004 David Flanagan. All rights reserved.
* This code is from the book Java Examples in a Nutshell, 3nd Edition.
* It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
* You may study, use, and modify it for any non-commercial purpose,
* including teaching and use in open-source projects.
* You may distribute it non-commercially as long as you retain this notice.
* For a commercial use license, or to purchase the book,
* please visit http://www.davidflanagan.com/javaexamples3.
*/
//package je3.net;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.Reader;
import java.net.Socket;
/**
* This program connects to a server at a specified host and port. It reads text
* from the console and sends it to the server. It reads text from the server
* and sends it to the console.
*/
public class GenericClient {
public static void main(String[] args) throws IOException {
try {
// Check the number of arguments
if (args.length != 2)
throw new IllegalArgumentException("Wrong number of args");
// Parse the host and port specifications
String host = args[0];
int port = Integer.parseInt(args[1]);
// Connect to the specified host and port
Socket s = new Socket(host, port);
// Set up streams for reading from and writing to the server.
// The from_server stream is final for use in the inner class below
final Reader from_server = new InputStreamReader(s.getInputStream());
PrintWriter to_server = new PrintWriter(s.getOutputStream());
// Set up streams for reading from and writing to the console
// The to_user stream is final for use in the anonymous class below
BufferedReader from_user = new BufferedReader(new InputStreamReader(System.in));
// Pass true for auto-flush on println()
final PrintWriter to_user = new PrintWriter(System.out, true);
// Tell the user that we've connected
to_user.println("Connected to " + s.getInetAddress() + ":" + s.getPort());
// Create a thread that gets output from the server and displays
// it to the user. We use a separate thread for this so that we
// can receive asynchronous output
Thread t = new Thread() {
public void run() {
char[] buffer = new char[1024];
int chars_read;
try {
// Read characters from the server until the
// stream closes, and write them to the console
while ((chars_read = from_server.read(buffer)) != -1) {
to_user.write(buffer, 0, chars_read);
to_user.flush();
}
} catch (IOException e) {
to_user.println(e);
}
// When the server closes the connection, the loop above
// will end. Tell the user what happened, and call
// System.exit(), causing the main thread to exit along
// with this one.
to_user.println("Connection closed by server.");
System.exit(0);
}
};
// Now start the server-to-user thread
t.start();
// In parallel, read the user's input and pass it on to the server.
String line;
while ((line = from_user.readLine()) != null) {
to_server.print(line + "\r\n");
to_server.flush();
}
// If the user types a Ctrl-D (Unix) or Ctrl-Z (Windows) to end
// their input, we'll get an EOF, and the loop above will exit.
// When this happens, we stop the server-to-user thread and close
// the socket.
s.close();
to_user.println("Connection closed by client.");
System.exit(0);
}
// If anything goes wrong, print an error message
catch (Exception e) {
System.err.println(e);
System.err.println("Usage: java GenericClient <hostname> <port>");
}
}
}
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