src/main/java/examples/mail/POP3Mail.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package examples.mail;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Locale;

import org.apache.commons.net.PrintCommandListener;
import org.apache.commons.net.pop3.POP3Client;
import org.apache.commons.net.pop3.POP3MessageInfo;
import org.apache.commons.net.pop3.POP3SClient;

/**
 * This is an example program demonstrating how to use the POP3[S]Client class.
 * This program connects to a POP3[S] server and retrieves the message
 * headers of all the messages, printing the From: and Subject: header
 * entries for each message.
 * <p>
 * Usage: POP3Mail <pop3[s] server hostname> <username> <password> [secure protocol, e.g. TLS]
 */
public final class POP3Mail
{

    public static final void printMessageInfo(BufferedReader reader, int id) throws IOException  {
        String from = "";
        String subject = "";
        String line;
        while ((line = reader.readLine()) != null)
        {
            String lower = line.toLowerCase(Locale.ENGLISH);
            if (lower.startsWith("from: ")) {
                from = line.substring(6).trim();
            }  else if (lower.startsWith("subject: ")) {
                subject = line.substring(9).trim();
            }
        }

        System.out.println(Integer.toString(id) + " From: " + from + "  Subject: " + subject);
    }

    public static void main(String[] args)
    {
        if (args.length < 3)
        {
            System.err.println(
                "Usage: POP3Mail <server[:port]> <username> <password|-|*|VARNAME> [TLS [true=implicit]]");
            System.exit(1);
        }

        String arg0[] = args[0].split(":");
        String server=arg0[0];
        String username = args[1];
        String password = args[2];
        // prompt for the password if necessary
        try {
            password = Utils.getPassword(username, password);
        } catch (IOException e1) {
            System.err.println("Could not retrieve password: " + e1.getMessage());
            return;
        }

        String proto = args.length > 3 ? args[3] : null;
        boolean implicit = args.length > 4 ? Boolean.parseBoolean(args[4]) : false;

        POP3Client pop3;

        if (proto != null) {
            System.out.println("Using secure protocol: "+proto);
            pop3 = new POP3SClient(proto, implicit);
        } else {
            pop3 = new POP3Client();
        }

        int port;
        if (arg0.length == 2) {
            port = Integer.parseInt(arg0[1]);
        } else {
            port = pop3.getDefaultPort();
        }
        System.out.println("Connecting to server "+server+" on "+port);

        // We want to timeout if a response takes longer than 60 seconds
        pop3.setDefaultTimeout(60000);

        // suppress login details
        pop3.addProtocolCommandListener(new PrintCommandListener(new PrintWriter(System.out), true));

        try
        {
            pop3.connect(server);
        }
        catch (IOException e)
        {
            System.err.println("Could not connect to server.");
            e.printStackTrace();
            return;
        }

        try
        {
            if (!pop3.login(username, password))
            {
                System.err.println("Could not login to server.  Check password.");
                pop3.disconnect();
                return;
            }

            POP3MessageInfo status = pop3.status();
            if (status == null) {
                System.err.println("Could not retrieve status.");
                pop3.logout();
                pop3.disconnect();
                return;
            }

            System.out.println("Status: " + status);

            POP3MessageInfo[] messages = pop3.listMessages();

            if (messages == null)
            {
                System.err.println("Could not retrieve message list.");
                pop3.logout();
                pop3.disconnect();
                return;
            }
            else if (messages.length == 0)
            {
                System.out.println("No messages");
                pop3.logout();
                pop3.disconnect();
                return;
            }

            System.out.println("Message count: " + messages.length);

            for (POP3MessageInfo msginfo : messages) {
                BufferedReader reader = (BufferedReader) pop3.retrieveMessageTop(msginfo.number, 0);

                if (reader == null) {
                    System.err.println("Could not retrieve message header.");
                    pop3.logout();
                    pop3.disconnect();
                    return;
                }
                printMessageInfo(reader, msginfo.number);
            }

            pop3.logout();
            pop3.disconnect();
        }
        catch (IOException e)
        {
            e.printStackTrace();
            return;
        }
    }
}