AddressVerifier.java Connects to an SMTP server and issues a expn request to display details about a mailbox on the server. Uses the following classes:
import java.net.*;
import java.io.*;
/** Given an e-mail address of the form user@host,
* connect to port 25 of the host and issue an
* 'expn' request for the user. Print the results.
*
* Taken from Core Web Programming from
* Prentice Hall and Sun Microsystems Press,
* .
* © 2001 Marty Hall and Larry Brown;
* may be freely used or adapted.
*/
public class AddressVerifier extends NetworkClient {
private String username;
public static void main(String[] args) {
if (args.length != 1) {
usage();
}
MailAddress address = new MailAddress(args[0]);
AddressVerifier verifier
= new AddressVerifier(address.getUsername(),
address.getHostname(), 25);
verifier.connect();
}
public AddressVerifier(String username, String hostname,
int port) {
super(hostname, port);
this.username = username;
}
/** NetworkClient, the parent class, automatically establishes
* the connection and then passes the Socket to
* handleConnection. This method does all the real work
* of talking to the mail server.
*/
// You can't use readLine, because it blocks. Blocking I/O
// by readLine is only appropriate when you know how many
// lines to read. Note that mail servers send a varying
// number of lines when you first connect or send no line
// closing the connection (as HTTP servers do), yielding
// null for readLine. Also, we'll assume that 1000 bytes
// is more than enough to handle any server welcome
// message and the actual EXPN response.
protected void handleConnection(Socket client) {
try {
PrintWriter out = SocketUtil.getWriter(client);
InputStream in = client.getInputStream();
byte[] response = new byte[1000];
// Clear out mail server's welcome message.
in.read(response);
out.println("EXPN " + username);
// Read the response to the EXPN command.
int numBytes = in.read(response);
// The 0 means to use normal ASCII encoding.
System.out.write(response, 0, numBytes);
out.println("QUIT");
client.close();
} catch(IOException ioe) {
System.out.println("Couldn't make connection: " + ioe);
}
}
/** If the wrong arguments, thn warn user. */
public static void usage() {
System.out.println ("You must supply an email address " +
"of the form 'username@hostname'.");
System.exit(-1);
}
}
MailAddress.java Separates the user and host components of an email address.
import java.util.*;
/** Takes a string of the form "user@host" and
* separates it into the "user" and "host" parts.
*
* Taken from Core Web Programming from
* Prentice Hall and Sun Microsystems Press,
* .
* © 2001 Marty Hall and Larry Brown;
* may be freely used or adapted.
*/
public class MailAddress {
private String username, hostname;
public MailAddress(String emailAddress) {
StringTokenizer tokenizer
= new StringTokenizer(emailAddress, "@");
this.username = getArg(tokenizer);
this.hostname = getArg(tokenizer);
}
private static String getArg(StringTokenizer tok) {
try { return(tok.nextToken()); }
catch (NoSuchElementException nsee) {
System.out.println("Illegal email address");
System.exit(-1);
return(null);
}
}
public String getUsername() {
return(username);
}
public String getHostname() {
return(hostname);
}
}
NetworkClient.java Starting point for a network client to communicate with a remote computer.
import java.net.*;
import java.io.*;
/** A starting point for network clients. You'll need to
* override handleConnection, but in many cases connect can
* remain unchanged. It uses SocketUtil to simplify the
* creation of the PrintWriter and BufferedReader.
*
* Taken from Core Web Programming from
* Prentice Hall and Sun Microsystems Press,
* .
* © 2001 Marty Hall and Larry Brown;
* may be freely used or adapted.
*/
public class NetworkClient {
protected String host;
protected int port;
/** Register host and port. The connection won't
* actually be established until you call
* connect.
*/
public NetworkClient(String host, int port) {
this.host = host;
this.port = port;
}
/** Establishes the connection, then passes the socket
* to handleConnection.
*/
public void connect() {
try {
Socket client = new Socket(host, port);
handleConnection(client);
} catch(UnknownHostException uhe) {
System.out.println("Unknown host: " + host);
uhe.printStackTrace();
} catch(IOException ioe) {
System.out.println("IOException: " + ioe);
ioe.printStackTrace();
}
}
/** This is the method you will override when
* making a network client for your task.
* The default version sends a single line
* ("Generic Network Client") to the server,
* reads one line of response, prints it, then exits.
*/
protected void handleConnection(Socket client)
throws IOException {
PrintWriter out = SocketUtil.getWriter(client);
BufferedReader in = SocketUtil.getReader(client);
out.println("Generic Network Client");
System.out.println
("Generic Network Client:n" +
"Made connection to " + host +
" and got '" + in.readLine() + "' in response");
client.close();
}
/** The hostname of the server we're contacting. */
public String getHost() {
return(host);
}
/** The port connection will be made on. */
public int getPort() {
return(port);
}
}
SocketUtil.java Provides utilities for wrapping a BufferedReader and PrintWriter around the Socket's input and output streams, respectively.
import java.net.*;
import java.io.*;
/** A shorthand way to create BufferedReaders and
* PrintWriters associated with a Socket.
*
* Taken from Core Web Programming from
* Prentice Hall and Sun Microsystems Press,
* .
* © 2001 Marty Hall and Larry Brown;
* may be freely used or adapted.
*/
public class SocketUtil {
/** Make a BufferedReader to get incoming data. */
public static BufferedReader getReader(Socket s)
throws IOException {
return(new BufferedReader(
new InputStreamReader(s.getInputStream())));
}
/** Make a PrintWriter to send outgoing data.
* This PrintWriter will automatically flush stream
* when println is called.
*/
public static PrintWriter getWriter(Socket s)
throws IOException {
// Second argument of true means autoflush.
return(new PrintWriter(s.getOutputStream(), true));
}
}
Note: Brought from our old site: http://www.salearningschool.com/example_codes/ on Jan 2nd, 2017 From: http://sitestree.com/?p=10229
Categories:Programming Code Examples, Java/J2EE/J2ME, Network Programming
Tags:Java/J2EE/J2MENetwork Programming
Post Data:2017-01-02 16:04:28
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