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Commons Net example source code file (SMTPClient.java)

This example Commons Net source code file (SMTPClient.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

dotterminatedmessagewriter, inetaddress, io, ioexception, ioexception, net, network, smtp, smtpclient, smtpclient, string, string, writer, writer

The Commons Net SMTPClient.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 org.apache.commons.net.smtp;

import java.io.IOException;
import java.io.Writer;
import java.net.InetAddress;

import org.apache.commons.net.io.DotTerminatedMessageWriter;

/***
 * SMTPClient encapsulates all the functionality necessary to send files
 * through an SMTP server.  This class takes care of all
 * low level details of interacting with an SMTP server and provides
 * a convenient higher level interface.  As with all classes derived
 * from {@link org.apache.commons.net.SocketClient},
 * you must first connect to the server with
 * {@link org.apache.commons.net.SocketClient#connect  connect }
 * before doing anything, and finally
 * {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
 * after you're completely finished interacting with the server.
 * Then you need to check the SMTP reply code to see if the connection
 * was successful.  For example:
 * <pre>
 *    try {
 *      int reply;
 *      client.connect("mail.foobar.com");
 *      System.out.print(client.getReplyString());
 *
 *      // After connection attempt, you should check the reply code to verify
 *      // success.
 *      reply = client.getReplyCode();
 *
 *      if(!SMTPReply.isPositiveCompletion(reply)) {
 *        client.disconnect();
 *        System.err.println("SMTP server refused connection.");
 *        System.exit(1);
 *      }
 *
 *      // Do useful stuff here.
 *      ...
 *    } catch(IOException e) {
 *      if(client.isConnected()) {
 *        try {
 *          client.disconnect();
 *        } catch(IOException f) {
 *          // do nothing
 *        }
 *      }
 *      System.err.println("Could not connect to server.");
 *      e.printStackTrace();
 *      System.exit(1);
 *    }
 * </pre>
 * <p>
 * Immediately after connecting is the only real time you need to check the
 * reply code (because connect is of type void).  The convention for all the
 * SMTP command methods in SMTPClient is such that they either return a
 * boolean value or some other value.
 * The boolean methods return true on a successful completion reply from
 * the SMTP server and false on a reply resulting in an error condition or
 * failure.  The methods returning a value other than boolean return a value
 * containing the higher level data produced by the SMTP command, or null if a
 * reply resulted in an error condition or failure.  If you want to access
 * the exact SMTP reply code causing a success or failure, you must call
 * {@link org.apache.commons.net.smtp.SMTP#getReplyCode  getReplyCode } after
 * a success or failure.
 * <p>
 * You should keep in mind that the SMTP server may choose to prematurely
 * close a connection for various reasons.  The SMTPClient class will detect a
 * premature SMTP server connection closing when it receives a
 * {@link org.apache.commons.net.smtp.SMTPReply#SERVICE_NOT_AVAILABLE SMTPReply.SERVICE_NOT_AVAILABLE }
 *  response to a command.
 * When that occurs, the method encountering that reply will throw
 * an {@link org.apache.commons.net.smtp.SMTPConnectionClosedException}
 * .
 * <code>SMTPConectionClosedException
 * is a subclass of <code> IOException  and therefore need not be
 * caught separately, but if you are going to catch it separately, its
 * catch block must appear before the more general <code> IOException 
 * catch block.  When you encounter an
 * {@link org.apache.commons.net.smtp.SMTPConnectionClosedException}
 * , you must disconnect the connection with
 * {@link #disconnect  disconnect() } to properly clean up the
 * system resources used by SMTPClient.  Before disconnecting, you may check
 * the last reply code and text with
 * {@link org.apache.commons.net.smtp.SMTP#getReplyCode  getReplyCode },
 * {@link org.apache.commons.net.smtp.SMTP#getReplyString  getReplyString },
 * and
 * {@link org.apache.commons.net.smtp.SMTP#getReplyStrings getReplyStrings}.
 * <p>
 * Rather than list it separately for each method, we mention here that
 * every method communicating with the server and throwing an IOException
 * can also throw a
 * {@link org.apache.commons.net.MalformedServerReplyException}
 * , which is a subclass
 * of IOException.  A MalformedServerReplyException will be thrown when
 * the reply received from the server deviates enough from the protocol
 * specification that it cannot be interpreted in a useful manner despite
 * attempts to be as lenient as possible.
 * <p>
 * <p>
 * @see SMTP
 * @see SimpleSMTPHeader
 * @see RelayPath
 * @see SMTPConnectionClosedException
 * @see org.apache.commons.net.MalformedServerReplyException
 ***/

public class SMTPClient extends SMTP
{

    /**
     * Default SMTPClient constructor.  Creates a new SMTPClient instance.
     */
    public SMTPClient() {  }

    /**
     * Overloaded constructor that takes an encoding specification
     * @param encoding The encoding to use
     * @since 2.0
     */
    public SMTPClient(String encoding) {
        super(encoding);
    }


    /***
     * At least one SMTPClient method ({@link #sendMessageData  sendMessageData })
     * does not complete the entire sequence of SMTP commands to complete a
     * transaction.  These types of commands require some action by the
     * programmer after the reception of a positive intermediate command.
     * After the programmer's code completes its actions, it must call this
     * method to receive the completion reply from the server and verify the
     * success of the entire transaction.
     * <p>
     * For example,
     * <pre>
     * writer = client.sendMessage();
     * if(writer == null) // failure
     *   return false;
     * header =
     *  new SimpleSMTPHeader("foobar@foo.com", "foo@foobar.com", "Re: Foo");
     * writer.write(header.toString());
     * writer.write("This is just a test");
     * writer.close();
     * if(!client.completePendingCommand()) // failure
     *   return false;
     * </pre>
     * <p>
     * @return True if successfully completed, false if not.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     ***/
    public boolean completePendingCommand() throws IOException
    {
        return SMTPReply.isPositiveCompletion(getReply());
    }


    /***
     * Login to the SMTP server by sending the HELO command with the
     * given hostname as an argument.  Before performing any mail commands,
     * you must first login.
     * <p>
     * @param hostname  The hostname with which to greet the SMTP server.
     * @return True if successfully completed, false if not.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     ***/
    public boolean login(String hostname) throws IOException
    {
        return SMTPReply.isPositiveCompletion(helo(hostname));
    }


    /***
     * Login to the SMTP server by sending the HELO command with the
     * client hostname as an argument.  Before performing any mail commands,
     * you must first login.
     * <p>
     * @return True if successfully completed, false if not.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     ***/
    public boolean login() throws IOException
    {
        String name;
        InetAddress host;

        host = getLocalAddress();
        name = host.getHostName();

        if (name == null)
            return false;

        return SMTPReply.isPositiveCompletion(helo(name));
    }


    /***
     * Set the sender of a message using the SMTP MAIL command, specifying
     * a reverse relay path.  The sender must be set first before any
     * recipients may be specified, otherwise the mail server will reject
     * your commands.
     * <p>
     * @param path  The reverse relay path pointing back to the sender.
     * @return True if successfully completed, false if not.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     ***/
    public boolean setSender(RelayPath path) throws IOException
    {
        return SMTPReply.isPositiveCompletion(mail(path.toString()));
    }


    /***
     * Set the sender of a message using the SMTP MAIL command, specifying
     * the sender's email address. The sender must be set first before any
     * recipients may be specified, otherwise the mail server will reject
     * your commands.
     * <p>
     * @param address  The sender's email address.
     * @return True if successfully completed, false if not.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     ***/
    public boolean setSender(String address) throws IOException
    {
        return SMTPReply.isPositiveCompletion(mail("<" + address + ">"));
    }


    /***
     * Add a recipient for a message using the SMTP RCPT command, specifying
     * a forward relay path.  The sender must be set first before any
     * recipients may be specified, otherwise the mail server will reject
     * your commands.
     * <p>
     * @param path  The forward relay path pointing to the recipient.
     * @return True if successfully completed, false if not.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     ***/
    public boolean addRecipient(RelayPath path) throws IOException
    {
        return SMTPReply.isPositiveCompletion(rcpt(path.toString()));
    }


    /***
     * Add a recipient for a message using the SMTP RCPT command, the
     * recipient's email address.  The sender must be set first before any
     * recipients may be specified, otherwise the mail server will reject
     * your commands.
     * <p>
     * @param address  The recipient's email address.
     * @return True if successfully completed, false if not.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     ***/
    public boolean addRecipient(String address) throws IOException
    {
        return SMTPReply.isPositiveCompletion(rcpt("<" + address + ">"));
    }



    /***
     * Send the SMTP DATA command in preparation to send an email message.
     * This method returns a DotTerminatedMessageWriter instance to which
     * the message can be written.  Null is returned if the DATA command
     * fails.
     * <p>
     * You must not issue any commands to the SMTP server (i.e., call any
     * (other methods) until you finish writing to the returned Writer
     * instance and close it.  The SMTP protocol uses the same stream for
     * issuing commands as it does for returning results.  Therefore the
     * returned Writer actually writes directly to the SMTP connection.
     * After you close the writer, you can execute new commands.  If you
     * do not follow these requirements your program will not work properly.
     * <p>
     * You can use the provided
     * {@link org.apache.commons.net.smtp.SimpleSMTPHeader}
     * class to construct a bare minimum header.
     * To construct more complicated headers you should
     * refer to RFC 822.  When the Java Mail API is finalized, you will be
     * able to use it to compose fully compliant Internet text messages.
     * The DotTerminatedMessageWriter takes care of doubling line-leading
     * dots and ending the message with a single dot upon closing, so all
     * you have to worry about is writing the header and the message.
     * <p>
     * Upon closing the returned Writer, you need to call
     * {@link #completePendingCommand  completePendingCommand() }
     * to finalize the transaction and verify its success or failure from
     * the server reply.
     * <p>
     * @return A DotTerminatedMessageWriter to which the message (including
     *      header) can be written.  Returns null if the command fails.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     ***/
    public Writer sendMessageData() throws IOException
    {
        if (!SMTPReply.isPositiveIntermediate(data()))
            return null;

        return new DotTerminatedMessageWriter(_writer);
    }


    /***
     * A convenience method for sending short messages.  This method fetches
     * the Writer returned by {@link #sendMessageData  sendMessageData() }
     * and writes the specified String to it.  After writing the message,
     * this method calls {@link #completePendingCommand completePendingCommand() }
     *  to finalize the transaction and returns
     * its success or failure.
     * <p>
     * @param message  The short email message to send.
     * @return True if successfully completed, false if not.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     ***/
    public boolean sendShortMessageData(String message) throws IOException
    {
        Writer writer;

        writer = sendMessageData();

        if (writer == null)
            return false;

        writer.write(message);
        writer.close();

        return completePendingCommand();
    }


    /***
     * A convenience method for a sending short email without having to
     * explicitly set the sender and recipient(s).  This method
     * sets the sender and recipient using
     * {@link #setSender  setSender } and
     * {@link #addRecipient  addRecipient }, and then sends the
     * message using {@link #sendShortMessageData  sendShortMessageData }.
     * <p>
     * @param sender  The email address of the sender.
     * @param recipient  The email address of the recipient.
     * @param message  The short email message to send.
     * @return True if successfully completed, false if not.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     ***/
    public boolean sendSimpleMessage(String sender, String recipient,
                                     String message)
    throws IOException
    {
        if (!setSender(sender))
            return false;

        if (!addRecipient(recipient))
            return false;

        return sendShortMessageData(message);
    }



    /***
     * A convenience method for a sending short email without having to
     * explicitly set the sender and recipient(s).  This method
     * sets the sender and recipients using
     * {@link #setSender  setSender } and
     * {@link #addRecipient  addRecipient }, and then sends the
     * message using {@link #sendShortMessageData  sendShortMessageData }.
     * <p>
     * @param sender  The email address of the sender.
     * @param recipients  An array of recipient email addresses.
     * @param message  The short email message to send.
     * @return True if successfully completed, false if not.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     ***/
    public boolean sendSimpleMessage(String sender, String[] recipients,
                                     String message)
    throws IOException
    {
        boolean oneSuccess = false;
        int count;

        if (!setSender(sender))
            return false;

        for (count = 0; count < recipients.length; count++)
        {
            if (addRecipient(recipients[count]))
                oneSuccess = true;
        }

        if (!oneSuccess)
            return false;

        return sendShortMessageData(message);
    }


    /***
     * Logout of the SMTP server by sending the QUIT command.
     * <p>
     * @return True if successfully completed, false if not.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     ***/
    public boolean logout() throws IOException
    {
        return SMTPReply.isPositiveCompletion(quit());
    }



    /***
     * Aborts the current mail transaction, resetting all server stored
     * sender, recipient, and mail data, cleaing all buffers and tables.
     * <p>
     * @return True if successfully completed, false if not.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     ***/
    public boolean reset() throws IOException
    {
        return SMTPReply.isPositiveCompletion(rset());
    }


    /***
     * Verify that a username or email address is valid, i.e., that mail
     * can be delivered to that mailbox on the server.
     * <p>
     * @param username  The username or email address to validate.
     * @return True if the username is valid, false if not.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     ***/
    public boolean verify(String username) throws IOException
    {
        int result;

        result = vrfy(username);

        return (result == SMTPReply.ACTION_OK ||
                result == SMTPReply.USER_NOT_LOCAL_WILL_FORWARD);
    }


    /***
     * Fetches the system help information from the server and returns the
     * full string.
     * <p>
     * @return The system help string obtained from the server.  null if the
     *       information could not be obtained.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *  command to the server or receiving a reply from the server.
     ***/
    public String listHelp() throws IOException
    {
        if (SMTPReply.isPositiveCompletion(help()))
            return getReplyString();
        return null;
    }


    /***
     * Fetches the help information for a given command from the server and
     * returns the full string.
     * <p>
     * @param command The command on which to ask for help.
     * @return The command help string obtained from the server.  null if the
     *       information could not be obtained.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *  command to the server or receiving a reply from the server.
     ***/
    public String listHelp(String command) throws IOException
    {
        if (SMTPReply.isPositiveCompletion(help(command)))
            return getReplyString();
        return null;
    }


    /***
     * Sends a NOOP command to the SMTP server.  This is useful for preventing
     * server timeouts.
     * <p>
     * @return True if successfully completed, false if not.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     ***/
    public boolean sendNoOp() throws IOException
    {
        return SMTPReply.isPositiveCompletion(noop());
    }

}

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