Java tutorial
/**************************************************************** * 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.james.protocols.pop3.core; import java.util.Arrays; import java.util.Collection; import java.util.Collections; import java.util.HashSet; import java.util.Set; import org.apache.commons.configuration.Configuration; import org.apache.commons.configuration.ConfigurationException; import org.apache.james.protocols.api.Request; import org.apache.james.protocols.api.Response; import org.apache.james.protocols.api.handler.CommandHandler; import org.apache.james.protocols.pop3.POP3Response; import org.apache.james.protocols.pop3.POP3Session; import org.apache.james.protocols.pop3.POP3StartTlsResponse; /** * Handler which offer STARTTLS implementation for POP3. STARTTLS is started * with the STSL command */ public class StlsCmdHandler implements CommandHandler<POP3Session>, CapaCapability { private static final Collection<String> COMMANDS = Collections.unmodifiableCollection(Arrays.asList("STLS")); private static final Set<String> CAPS = Collections.unmodifiableSet(new HashSet<String>(Arrays.asList("STLS"))); private static final Response BEGIN_TLS = new POP3StartTlsResponse(POP3Response.OK_RESPONSE, "Begin TLS negotiation").immutable(); @Override public void init(Configuration config) throws ConfigurationException { } @Override public void destroy() { } /** * @see CommandHandler#onCommand(org.apache.james.protocols.api.ProtocolSession, Request) */ public Response onCommand(POP3Session session, Request request) { // check if starttls is supported, the state is the right one and it was // not started before if (session.isStartTLSSupported() && session.getHandlerState() == POP3Session.AUTHENTICATION_READY && session.isTLSStarted() == false) { return BEGIN_TLS; } else { return POP3Response.ERR; } } /** * @see org.apache.james.pop3server.core.CapaCapability#getImplementedCapabilities(org.apache.james.pop3server.POP3Session) */ @SuppressWarnings("unchecked") public Set<String> getImplementedCapabilities(POP3Session session) { if (session.isStartTLSSupported() && session.getHandlerState() == POP3Session.AUTHENTICATION_READY) { return CAPS; } else { return Collections.EMPTY_SET; } } /** * @see org.apache.james.protocols.api.handler.CommandHandler#getImplCommands() */ public Collection<String> getImplCommands() { return COMMANDS; } }