Java – IMAP client in Java: JavaMail API or Apache Commons Net

apache-commonsemailimapjakarta-mailjava

I have to implement an IMAP Client in Java.

Which advantages has using the Apache Commons Net library? Does it make the implementation robust and more flexible?

How do I have to handle return values, it always produces strings.

For example:

public static void main(String[] args) throws Exception {
    IMAPClient client = new IMAPClient();
    client.connect(SERVER);
    client.login(USERNAME, PASSWORD);
    client.select("INBOX");
    client.fetch("1", "body[header]");
}

and we can direct the output to string by

client.addProtocolCommandListener(new PrintCommandListener(System.out, true));

But how can I get a list of folders as folder instances instead of pure string output?

Best Answer

Short story : it depends on your real requirements.

If your client is mainly focused on sending and reading mail, the JavaMail API is a de-facto standard high-level API, and it will be much simpler to compose mail, add headers and/or attachements.

On the other hand, if you intend to offer all the possibilities of the IMAP protocol, the lower-level Apache Commons Net library will allow more detailed operations, at the cost of more boiler plate code for simple operations.

Just to complete this answer, you should not forget Apache Commons Email, which according to the home page of the project is built on top of the Java Mail API, which it aims to simplify. It is much closer to JavaMail than to Commons Net.

Without knowing more of what one wants to do, it is hard to give a more precise answer...

Steps to create a sample Project:

MailSenderActivity.java:

public class MailSenderActivity extends Activity {
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        final Button send = (Button) this.findViewById(R.id.send);
        send.setOnClickListener(new View.OnClickListener() {
            
            public void onClick(View v) {
                try {   
                    GMailSender sender = new GMailSender("username@gmail.com", "password");
                    sender.sendMail("This is Subject",   
                            "This is Body",   
                            "user@gmail.com",   
                            "user@yahoo.com");   
                } catch (Exception e) {   
                    Log.e("SendMail", e.getMessage(), e);   
                } 
                
            }
        });
        
    }
}

GMailSender.java:

public class GMailSender extends javax.mail.Authenticator {   
    private String mailhost = "smtp.gmail.com";   
    private String user;   
    private String password;   
    private Session session;   
  
    static {   
        Security.addProvider(new com.provider.JSSEProvider());   
    }  
  
    public GMailSender(String user, String password) {   
        this.user = user;   
        this.password = password;   
  
        Properties props = new Properties();   
        props.setProperty("mail.transport.protocol", "smtp");   
        props.setProperty("mail.host", mailhost);   
        props.put("mail.smtp.auth", "true");   
        props.put("mail.smtp.port", "465");   
        props.put("mail.smtp.socketFactory.port", "465");   
        props.put("mail.smtp.socketFactory.class",   
                "javax.net.ssl.SSLSocketFactory");   
        props.put("mail.smtp.socketFactory.fallback", "false");   
        props.setProperty("mail.smtp.quitwait", "false");   
  
        session = Session.getDefaultInstance(props, this);   
    }   
  
    protected PasswordAuthentication getPasswordAuthentication() {   
        return new PasswordAuthentication(user, password);   
    }   
  
    public synchronized void sendMail(String subject, String body, String sender, String recipients) throws Exception {   
        try{
        MimeMessage message = new MimeMessage(session);   
        DataHandler handler = new DataHandler(new ByteArrayDataSource(body.getBytes(), "text/plain"));   
        message.setSender(new InternetAddress(sender));   
        message.setSubject(subject);   
        message.setDataHandler(handler);   
        if (recipients.indexOf(',') > 0)   
            message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(recipients));   
        else  
            message.setRecipient(Message.RecipientType.TO, new InternetAddress(recipients));   
        Transport.send(message);   
        }catch(Exception e){
            
        }
    }   
  
    public class ByteArrayDataSource implements DataSource {   
        private byte[] data;   
        private String type;   
  
        public ByteArrayDataSource(byte[] data, String type) {   
            super();   
            this.data = data;   
            this.type = type;   
        }   
  
        public ByteArrayDataSource(byte[] data) {   
            super();   
            this.data = data;   
        }   
  
        public void setType(String type) {   
            this.type = type;   
        }   
  
        public String getContentType() {   
            if (type == null)   
                return "application/octet-stream";   
            else  
                return type;   
        }   
  
        public InputStream getInputStream() throws IOException {   
            return new ByteArrayInputStream(data);   
        }   
  
        public String getName() {   
            return "ByteArrayDataSource";   
        }   
  
        public OutputStream getOutputStream() throws IOException {   
            throw new IOException("Not Supported");   
        }   
    }   
}

JSSEProvider.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.
 */

/**
 * @author Alexander Y. Kleymenov
 * @version $Revision$
 */


import java.security.AccessController;
import java.security.Provider;

public final class JSSEProvider extends Provider {

    public JSSEProvider() {
        super("HarmonyJSSE", 1.0, "Harmony JSSE Provider");
        AccessController.doPrivileged(new java.security.PrivilegedAction<Void>() {
            public Void run() {
                put("SSLContext.TLS",
                        "org.apache.harmony.xnet.provider.jsse.SSLContextImpl");
                put("Alg.Alias.SSLContext.TLSv1", "TLS");
                put("KeyManagerFactory.X509",
                        "org.apache.harmony.xnet.provider.jsse.KeyManagerFactoryImpl");
                put("TrustManagerFactory.X509",
                        "org.apache.harmony.xnet.provider.jsse.TrustManagerFactoryImpl");
                return null;
            }
        });
    }
}

ADD 3 jars found in the following link to your Android Project

Click here - How to add External Jars

And don't forget to add this line in your manifest:

<uses-permission android:name="android.permission.INTERNET" />

Just click below link to change account access for less secure apps https://www.google.com/settings/security/lesssecureapps

Run the project and check your recipient mail account for the mail. Cheers!

P.S. And don't forget that you cannot do network operation from any Activity in android. Hence it is recommended to use AsyncTask or IntentService to avoid network on main thread exception.

Jar files: https://code.google.com/archive/p/javamail-android/

Java – Accessing emails from gmail using IMAP ( javamail API)

Is one of the accounts using non-english UI by any chance?

Gmail folder names are localized with respect to the user localization settings.

Currently the only way to get the name of the localized folder is by using XLIST command.

Best Answer

Related Solutions

Java – Sending Email in Android using JavaMail API without using the default/built-in app

Steps to create a sample Project:

Java – Accessing emails from gmail using IMAP ( javamail API)

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