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Commons Net example source code file (POP3Mail.java)

This example Commons Net source code file (POP3Mail.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons Net tags/keywords

bufferedreader, io, ioexception, ioexception, pop3client, pop3mail, pop3mail, pop3messageinfo, pop3messageinfo, pop3sclient, printcommandlistener, string, string, tls, usage, util

The Commons Net POP3Mail.java source code

/*
 * 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>   [secure protocol, e.g. TLS]
 * <p>
 */
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 final void main(String[] args)
    {
        if (args.length < 3)
        {
            System.err.println(
                "Usage: POP3Mail <pop3 server hostname>   [TLS [true=implicit]]");
            System.exit(1);
        }

        String server = args[0];
        String username = args[1];
        String password = args[2];

        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();
        }
        System.out.println("Connecting to server "+server+" on "+pop3.getDefaultPort());

        // 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();
            System.exit(1);
        }

        try
        {
            if (!pop3.login(username, password))
            {
                System.err.println("Could not login to server.  Check password.");
                pop3.disconnect();
                System.exit(1);
            }

            POP3MessageInfo[] messages = pop3.listMessages();

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

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

                if (reader == null) {
                    System.err.println("Could not retrieve message header.");
                    pop3.disconnect();
                    System.exit(1);
                }
                printMessageInfo(reader, msginfo.number);
            }

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

Other Commons Net examples (source code examples)

Here is a short list of links related to this Commons Net POP3Mail.java source code file:

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