public class SMTPClient extends SMTP
SocketClient,
you must first connect to the server with
connect
before doing anything, and finally
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:
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);
}
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
getReplyCode after
a success or failure.
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
SMTPReply.SERVICE_NOT_AVAILABLE
response to a command.
When that occurs, the method encountering that reply will throw
an SMTPConnectionClosedException
.
SMTPConectionClosedException
is a subclass of 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 IOException
catch block. When you encounter an
SMTPConnectionClosedException
, you must disconnect the connection with
disconnect() to properly clean up the
system resources used by SMTPClient. Before disconnecting, you may check
the last reply code and text with
getReplyCode ,
getReplyString ,
and
getReplyStrings.
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
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.
_commandSupport_, DEFAULT_PORT, encoding_defaultPort_, _hostname_, _input_, _output_, _serverSocketFactory_, _socket_, _socketFactory_, _timeout_, connectTimeout, NETASCII_EOL| Constructor and Description |
|---|
SMTPClient()
Default SMTPClient constructor.
|
SMTPClient(String encoding)
Overloaded constructor that takes an encoding specification
|
| Modifier and Type | Method and Description |
|---|---|
boolean |
addRecipient(RelayPath path)
Add a recipient for a message using the SMTP RCPT command, specifying
a forward relay path.
|
boolean |
addRecipient(String address)
Add a recipient for a message using the SMTP RCPT command, the
recipient's email address.
|
boolean |
completePendingCommand()
At least one SMTPClient method (
sendMessageData )
does not complete the entire sequence of SMTP commands to complete a
transaction. |
String |
listHelp()
Fetches the system help information from the server and returns the
full string.
|
String |
listHelp(String command)
Fetches the help information for a given command from the server and
returns the full string.
|
boolean |
login()
Login to the SMTP server by sending the HELO command with the
client hostname as an argument.
|
boolean |
login(String hostname)
Login to the SMTP server by sending the HELO command with the
given hostname as an argument.
|
boolean |
logout()
Logout of the SMTP server by sending the QUIT command.
|
boolean |
reset()
Aborts the current mail transaction, resetting all server stored
sender, recipient, and mail data, cleaing all buffers and tables.
|
Writer |
sendMessageData()
Send the SMTP DATA command in preparation to send an email message.
|
boolean |
sendNoOp()
Sends a NOOP command to the SMTP server.
|
boolean |
sendShortMessageData(String message)
A convenience method for sending short messages.
|
boolean |
sendSimpleMessage(String sender,
String[] recipients,
String message)
A convenience method for a sending short email without having to
explicitly set the sender and recipient(s).
|
boolean |
sendSimpleMessage(String sender,
String recipient,
String message)
A convenience method for a sending short email without having to
explicitly set the sender and recipient(s).
|
boolean |
setSender(RelayPath path)
Set the sender of a message using the SMTP MAIL command, specifying
a reverse relay path.
|
boolean |
setSender(String address)
Set the sender of a message using the SMTP MAIL command, specifying
the sender's email address.
|
boolean |
verify(String username)
Verify that a username or email address is valid, i.e., that mail
can be delivered to that mailbox on the server.
|
_connectAction_, data, disconnect, expn, getCommandSupport, getReply, getReplyCode, getReplyString, getReplyStrings, helo, help, help, mail, noop, quit, rcpt, removeProtocolCommandistener, rset, saml, send, sendCommand, sendCommand, sendCommand, sendCommand, soml, turn, vrfyaddProtocolCommandListener, connect, connect, connect, connect, connect, connect, createCommandSupport, fireCommandSent, fireReplyReceived, getCharset, getCharsetName, getConnectTimeout, getDefaultPort, getDefaultTimeout, getKeepAlive, getLocalAddress, getLocalPort, getProxy, getReceiveBufferSize, getRemoteAddress, getRemotePort, getSendBufferSize, getServerSocketFactory, getSoLinger, getSoTimeout, getTcpNoDelay, isAvailable, isConnected, removeProtocolCommandListener, setCharset, setConnectTimeout, setDefaultPort, setDefaultTimeout, setKeepAlive, setProxy, setReceiveBufferSize, setSendBufferSize, setServerSocketFactory, setSocketFactory, setSoLinger, setSoTimeout, setTcpNoDelay, verifyRemotepublic SMTPClient()
public SMTPClient(String encoding)
encoding - The encoding to usepublic boolean completePendingCommand() throws IOException
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.
For example,
writer = client.sendMessageData();
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;
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.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
hostname - The hostname with which to greet the SMTP server.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.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
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.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
path - The reverse relay path pointing back to the sender.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.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
address - The sender's email address.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.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
path - The forward relay path pointing to the recipient.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.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
address - The recipient's email address.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.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
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.
You can use the provided
SimpleSMTPHeader
class to construct a bare minimum header.
To construct more complicated headers you should
refer to RFC 5322. 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.
Upon closing the returned Writer, you need to call
completePendingCommand()
to finalize the transaction and verify its success or failure from
the server reply.
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.IOException - If an I/O error occurs while either sending a
command to the server or receiving a reply from the server.sendShortMessageData(String)public boolean sendShortMessageData(String message) throws IOException
sendMessageData()
and writes the specified String to it. After writing the message,
this method calls completePendingCommand()
to finalize the transaction and returns
its success or failure.
message - The short email message to send.
This must include the headers and the body, but not the trailing "."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.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
setSender and
addRecipient , and then sends the
message using sendShortMessageData .
sender - The email address of the sender.recipient - The email address of the recipient.message - The short email message to send.
This must include the headers and the body, but not the trailing "."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.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
setSender and
addRecipient, and then sends the
message using sendShortMessageData.
Note that the method ignores failures when calling
addRecipient so long as
at least one call succeeds. If no recipients can be successfully
added then the method will fail (and does not attempt to
send the message)
sender - The email address of the sender.recipients - An array of recipient email addresses.message - The short email message to send.
This must include the headers and the body, but not the trailing "."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.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
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.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
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.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
username - The username or email address to validate.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.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
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.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
command - The command on which to ask for help.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.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
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.IOException - If an I/O error occurs while either sending a
command to the server or receiving a reply from the server.Copyright © 2001–2017 The Apache Software Foundation. All rights reserved.