pop3folder.java

此源码是在sun站点上提供的javamail基础上改进。用来解决中文邮件或很多国际间邮件乱码问题。版权属于sun公司。不过当你开发webmail程序时做邮件展示时

	    close(false);
	} catch (MessagingException ex) { }
	return false;
    }

    /**
     * Always returns an empty <code>Flags</code> object because
     * the POP3 protocol doesn't support any permanent flags.
     *
     * @return	empty Flags object
     */
    public Flags getPermanentFlags() {
	return new Flags(); // empty flags object
    }

    /**
     * Will not change while the folder is open because the POP3
     * protocol doesn't support notification of new messages
     * arriving in open folders.
     */
    public synchronized int getMessageCount() throws MessagingException {
	if (!opened)
	    return -1;
	checkReadable();
	return total;
    }

    public synchronized Message getMessage(int msgno)
					throws MessagingException {
	checkOpen();

	POP3Message m;

	// Assuming that msgno is <= total 
	if ((m = (POP3Message)message_cache.elementAt(msgno-1)) == null) {
	    m = createMessage(this, msgno);
	    message_cache.setElementAt(m, msgno-1);
	}
	return m;
    }

    protected POP3Message createMessage(Folder f, int msgno)
				throws MessagingException {
	POP3Message m = null;
	Constructor cons = ((POP3Store)store).messageConstructor;
	if (cons != null) {
	    try {
		Object[] o = { this, new Integer(msgno) };
		m = (POP3Message)cons.newInstance(o);
	    } catch (Exception ex) {
		// ignore
	    }
	}
	if (m == null)
	    m = new POP3Message(this, msgno);
	return m;
    }

    /**
     * Always throws <code>MethodNotSupportedException</code>
     * because the POP3 protocol doesn't support appending messages.
     *
     * @exception	MethodNotSupportedException	always
     */
    public void appendMessages(Message[] msgs) throws MessagingException {
	throw new MethodNotSupportedException("Append not supported");	
    }

    /**
     * Always throws <code>MethodNotSupportedException</code>
     * because the POP3 protocol doesn't support expunging messages
     * without closing the folder; call the {@link #close close} method
     * with the <code>expunge</code> argument set to <code>true</code>
     * instead.
     *
     * @exception	MethodNotSupportedException	always
     */
    public Message[] expunge() throws MessagingException {
	throw new MethodNotSupportedException("Expunge not supported");
    }

    /**
     * Prefetch information about POP3 messages.
     * If the FetchProfile contains <code>UIDFolder.FetchProfileItem.UID</code>,
     * POP3 UIDs for all messages in the folder are fetched using the POP3
     * UIDL command.
     * If the FetchProfile contains <code>FetchProfile.Item.ENVELOPE</code>,
     * the headers and size of all messages are fetched using the POP3 TOP
     * and LIST commands.
     */
    public synchronized void fetch(Message[] msgs, FetchProfile fp)
				throws MessagingException {
	checkReadable();
	if (!doneUidl && fp.contains(UIDFolder.FetchProfileItem.UID)) {
	    /*
	     * Since the POP3 protocol only lets us fetch the UID
	     * for a single message or for all messages, we go ahead
	     * and fetch UIDs for all messages here, ignoring the msgs
	     * parameter.  We could be more intelligent and base this
	     * decision on the number of messages fetched, or the
	     * percentage of the total number of messages fetched.
	     */
	    String[] uids = new String[message_cache.size()];
	    try {
		if (!port.uidl(uids))
		    return;
	    } catch (EOFException eex) {
		close(false);
		throw new FolderClosedException(this, eex.toString());
	    } catch (IOException ex) {
		throw new MessagingException("error getting UIDL", ex);
	    }
	    for (int i = 0; i < uids.length; i++) {
		if (uids[i] == null)
		    continue;
		POP3Message m = (POP3Message)getMessage(i + 1);
		m.uid = uids[i];
	    }
	    doneUidl = true;	// only do this once
	}
	if (fp.contains(FetchProfile.Item.ENVELOPE)) {
	    for (int i = 0; i < msgs.length; i++) {
		try {
		    POP3Message msg = (POP3Message)msgs[i];
		    // fetch headers
		    msg.getHeader("");
		    // fetch message size
		    msg.getSize();
		} catch (MessageRemovedException mex) {
		    // should never happen, but ignore it if it does
		}
	    }
	}
    }

    /**
     * Return the unique ID string for this message, or null if
     * not available.  Uses the POP3 UIDL command.
     *
     * @return          unique ID string
     * @exception	MessagingException
     */
    public synchronized String getUID(Message msg) throws MessagingException {
	checkOpen();
	POP3Message m = (POP3Message)msg;
	try {
	    if (m.uid == POP3Message.UNKNOWN)
		m.uid = port.uidl(m.getMessageNumber());
	    return m.uid;
	} catch (EOFException eex) {
	    close(false);
	    throw new FolderClosedException(this, eex.toString());
	} catch (IOException ex) {
	    throw new MessagingException("error getting UIDL", ex);
	}
    }

    /**
     * Return the size of this folder, as was returned by the POP3 STAT
     * command when this folder was opened.
     *
     * @return		folder size
     * @exception	IllegalStateException	if the folder isn't open
     */
    public synchronized int getSize() throws MessagingException {
	checkOpen();
	return size;
    }

    /**
     * Return the sizes of all messages in this folder, as returned
     * by the POP3 LIST command.  Each entry in the array corresponds
     * to a message; entry <i>i</i> corresponds to message number <i>i+1</i>.
     *
     * @return		array of message sizes
     * @exception	IllegalStateException	if the folder isn't open
     * @since		JavaMail 1.3.3
     */
    public synchronized int[] getSizes() throws MessagingException {
	checkOpen();
	int sizes[] = new int[total];
	InputStream is = null;
	LineInputStream lis = null;
	try {
	    is = port.list();
	    lis = new LineInputStream(is);
	    String line;
	    while ((line = lis.readLine()) != null) {
		try {
		    StringTokenizer st = new StringTokenizer(line);
		    int msgnum = Integer.parseInt(st.nextToken());
		    int size = Integer.parseInt(st.nextToken());
		    if (msgnum > 0 && msgnum <= total)
			sizes[msgnum - 1] = size;
		} catch (Exception e) {
		}
	    }
	} catch (IOException ex) {
	    // ignore it?
	} finally {
	    try {
		if (lis != null)
		    lis.close();
	    } catch (IOException cex) { }
	    try {
		if (is != null)
		    is.close();
	    } catch (IOException cex) { }
	}
	return sizes;
    }

    /**
     * Return the raw results of the POP3 LIST command with no arguments.
     *
     * @return		InputStream containing results
     * @exception	IllegalStateException	if the folder isn't open
     * @since		JavaMail 1.3.3
     */
    public synchronized InputStream listCommand()
				throws MessagingException, IOException {
	checkOpen();
	return port.list();
    }

    /**
     * Close the folder when we're finalized.
     */
    protected void finalize() throws Throwable {
	super.finalize();
	close(false);
    }

    /* Ensure the folder is open */
    void checkOpen() throws IllegalStateException {
	if (!opened) 
	    throw new IllegalStateException("Folder is not Open");
    }

    /* Ensure the folder is not open */
    void checkClosed() throws IllegalStateException {
	if (opened) 
	    throw new IllegalStateException("Folder is Open");
    }

    /* Ensure the folder is open & readable */
    void checkReadable() throws IllegalStateException {
	if (!opened || (mode != READ_ONLY && mode != READ_WRITE))
	    throw new IllegalStateException("Folder is not Readable");
    }

    /* Ensure the folder is open & writable */
    void checkWritable() throws IllegalStateException {
	if (!opened || mode != READ_WRITE)
	    throw new IllegalStateException("Folder is not Writable");
    }

    /**
     * Centralize access to the Protocol object by POP3Message
     * objects so that they will fail appropriately when the folder
     * is closed.
     */
    Protocol getProtocol() throws MessagingException {
	checkOpen();
	return port;
    }

    /*
     * Only here to make accessible to POP3Message.
     */
    protected void notifyMessageChangedListeners(int type, Message m) {
	super.notifyMessageChangedListeners(type, m);
    }
}