linearprocessor.java

java 开发的邮件服务器平台。支持以下协议。 协议可以修改为自己的专门标识

        //  the array indicates which matcher/mailet (stage in the linear
        //  processor) that this Mail needs to be processed.
        //  e.g., a Mail in unprocessed[0] needs to be
        //  processed by the first matcher/mailet.
        //
        //  It is a List of Mail objects at each array spot as multiple Mail
        //  objects could be at the same stage.
        //
        //  Note that every Mail object in this array will either be the 
        //  original Mail object passed in, or a result of this method's
        //  (and hence this thread's) processing.

        List[] unprocessed = new List[matchers.size() + 1];

        for (int i = 0; i < unprocessed.length; i++) {
            // No need to use synchronization, as this is totally
            // local to the method
            unprocessed[i] = new ArrayList();
        }

        //Add the object to the bottom of the list
        unprocessed[0].add(mail);

        //This is the original state of the message
        String originalState = mail.getState();

        //We'll use these as temporary variables in the loop
        mail = null;  // the message we're currently processing
        int i = 0;    // where in the stage we're looking
        while (true) {
            //  The last element in the unprocessed array has mail messages
            //  that have completed all stages.  We want them to just die,
            //  so we clear that spot to allow garbage collection of the
            //  objects.
            //
            //  Please note that the presence of the terminating mailet at the end
            //  of the chain is critical to the proper operation
            //  of the LinearProcessor code.  If this mailet is not placed
            //  at the end of the chain with a terminating matcher, there is a 
            //  potential for configuration or implementation errors to 
            //  lead to mails trapped in the spool.  This matcher/mailet
            //  combination is added when the closeProcessorList method
            //  is called.
            unprocessed[unprocessed.length - 1].clear();

            //initialize the mail reference we will be searching on
            mail = null;

            //Scan through all stages, trying to find a message to process
            for (i = 0; i < unprocessed.length; i++) {
                if (unprocessed[i].size() > 0) {
                    //Get the first element from the queue, and remove it from there
                    mail = (MailImpl)unprocessed[i].remove(0);
                    break;
                }
            }

            //Check it we found anything
            if (mail == null) {
                //We found no messages to process... we're done servicing the mail object
                return;
            }


            //Call the matcher and find what recipients match
            Collection recipients = null;
            Matcher matcher = (Matcher) matchers.get(i);
            StringBuffer logMessageBuffer = null;
            if (getLogger().isDebugEnabled()) {
                logMessageBuffer =
                    new StringBuffer(128)
                            .append("Checking ")
                            .append(mail.getName())
                            .append(" with ")
                            .append(matcher);
                getLogger().debug(logMessageBuffer.toString());
            }
            try {
                recipients = matcher.match(mail);
                if (recipients == null) {
                    //In case the matcher returned null, create an empty Collection
                    recipients = new ArrayList(0);
                } else if (recipients != mail.getRecipients()) {
                    //Make sure all the objects are MailAddress objects
                    verifyMailAddresses(recipients);
                }
            } catch (MessagingException me) {
                // look in the matcher's mailet's init attributes
                MailetConfig mailetConfig = ((Mailet) mailets.get(i)).getMailetConfig();
                String onMatchException = ((MailetConfigImpl) mailetConfig).getInitAttribute("onMatchException");
                if (onMatchException == null) {
                    onMatchException = Mail.ERROR;
                } else {
                    onMatchException = onMatchException.trim().toLowerCase(Locale.US);
                }
                if (onMatchException.compareTo("nomatch") == 0) {
                    //In case the matcher returned null, create an empty Collection
                    recipients = new ArrayList(0);
                } else if (onMatchException.compareTo("matchall") == 0) {
                    recipients = mail.getRecipients();
                    // no need to verify addresses
                } else {
                    handleException(me, mail, matcher.getMatcherConfig().getMatcherName(), onMatchException);
                }
            }

            // Split the recipients into two pools.  notRecipients will contain the
            // recipients on the message that the matcher did not return.
            Collection notRecipients;
            if (recipients == mail.getRecipients() || recipients.size() == 0) {
                notRecipients = new ArrayList(0);
            } else {
                notRecipients = new ArrayList(mail.getRecipients());
                notRecipients.removeAll(recipients);
            }

            if (recipients.size() == 0) {
                //Everything was not a match... store it in the next spot in the array
                unprocessed[i + 1].add(mail);
                continue;
            }
            if (notRecipients.size() != 0) {
                // There are a mix of recipients and not recipients.
                // We need to clone this message, put the notRecipients on the clone
                // and store it in the next spot
                MailImpl notMail = (MailImpl)mail.duplicate(newName(mail));
                notMail.setRecipients(notRecipients);
                unprocessed[i + 1].add(notMail);
                //We have to set the reduce possible recipients on the old message
                mail.setRecipients(recipients);
            }
            // We have messages that need to process... time to run the mailet.
            Mailet mailet = (Mailet) mailets.get(i);
            if (getLogger().isDebugEnabled()) {
                logMessageBuffer =
                    new StringBuffer(128)
                            .append("Servicing ")
                            .append(mail.getName())
                            .append(" by ")
                            .append(mailet.getMailetInfo());
                getLogger().debug(logMessageBuffer.toString());
            }
            try {
                mailet.service(mail);
                // Make sure all the recipients are still MailAddress objects
                verifyMailAddresses(mail.getRecipients());
            } catch (MessagingException me) {
                MailetConfig mailetConfig = mailet.getMailetConfig();
                String onMailetException = ((MailetConfigImpl) mailetConfig).getInitAttribute("onMailetException");
                if (onMailetException == null) {
                    onMailetException = Mail.ERROR;
                } else {
                    onMailetException = onMailetException.trim().toLowerCase(Locale.US);
                }
                if (onMailetException.compareTo("ignore") == 0) {
                    // ignore the exception and continue
                    // this option should not be used if the mail object can be changed by the mailet
                    verifyMailAddresses(mail.getRecipients());
                } else {
                    handleException(me, mail, mailet.getMailetConfig().getMailetName(), onMailetException);
                }
            }

            // See if the state was changed by the mailet
            if (!mail.getState().equals(originalState)) {
                //If this message was ghosted, we just want to let it die
                if (mail.getState().equals(Mail.GHOST)) {
                    // let this instance die...
                    mail = null;
                    continue;
                }
                // This was just set to another state requiring further processing... 
                // Store this back in the spool and it will get picked up and 
                // run in that processor
                spool.store(mail);
                mail = null;
                continue;
            } else {
                // Ok, we made it through with the same state... move it to the next
                //  spot in the array
                unprocessed[i + 1].add(mail);
            }

        }
    }

    /**
     * Create a unique new primary key name.
     *
     * @param mail the mail to use as the basis for the new mail name
     * 
     * @return a new name
     */
    private String newName(MailImpl mail) {
        StringBuffer nameBuffer =
            new StringBuffer(64)
                    .append(mail.getName())
                    .append("-!")
                    .append(random.nextInt(1048576));
        return nameBuffer.toString();
    }



    /**
     * Checks that all objects in this class are of the form MailAddress.
     *
     * @throws MessagingException when the <code>Collection</code> contains objects that are not <code>MailAddress</code> objects
     */
    private void verifyMailAddresses(Collection col) throws MessagingException {
        try {
            MailAddress addresses[] = (MailAddress[])col.toArray(new MailAddress[0]);

            // Why is this here?  According to the javadoc for
            // java.util.Collection.toArray(Object[]), this should
            // never happen.  The exception will be thrown.
            if (addresses.length != col.size()) {
                throw new MailetException("The recipient list contains objects other than MailAddress objects");
            }
        } catch (ArrayStoreException ase) {
            throw new MailetException("The recipient list contains objects other than MailAddress objects");
        }
    }

    /**
     * This is a helper method that updates the state of the mail object to
     * Mail.ERROR as well as recording the exception to the log
     *
     * @param me the exception to be handled
     * @param mail the mail being processed when the exception was generated
     * @param offendersName the matcher or mailet than generated the exception
     * @param nextState the next state to set
     *
     * @throws MessagingException thrown always, rethrowing the passed in exception
     */
    private void handleException(MessagingException me, Mail mail, String offendersName, String nextState) throws MessagingException {
        System.err.println("exception! " + me);
        mail.setState(nextState);
        StringWriter sout = new StringWriter();
        PrintWriter out = new PrintWriter(sout, true);
        StringBuffer exceptionBuffer =
            new StringBuffer(128)
                    .append("Exception calling ")
                    .append(offendersName)
                    .append(": ")
                    .append(me.getMessage());
        out.println(exceptionBuffer.toString());
        Exception e = me;
        while (e != null) {
            e.printStackTrace(out);
            if (e instanceof MessagingException) {
                e = ((MessagingException)e).getNextException();
            } else {
                e = null;
            }
        }
        String errorString = sout.toString();
        mail.setErrorMessage(errorString);
        getLogger().error(errorString);
        throw me;
    }
}