001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.shiro.web.filter.session;
020
021import org.apache.shiro.subject.support.DefaultSubjectContext;
022import org.apache.shiro.web.filter.PathMatchingFilter;
023
024import javax.servlet.ServletRequest;
025import javax.servlet.ServletResponse;
026
027/**
028 * A {@code PathMatchingFilter} that will disable creating new Sessions during the request.  This is a useful
029 * filter to place in the front of any filter chains that may result in REST, SOAP or other service invocations that
030 * are not intended to participate in a session.
031 * <p/>
032 * This filter enables the following behavior:
033 * <ol>
034 * <li>If a {@code Subject} does not yet have a Session by the time this filter is called, this filter effectively
035 * disables all calls to {@code subject}.{@link org.apache.shiro.subject.Subject#getSession() getSession()} and
036 * {@code subject}.{@link org.apache.shiro.subject.Subject#getSession(boolean) getSession(true)}.  If either are called
037 * during the request, an exception will be thrown.</li>
038 * <li>
039 * However, if the {@code Subject} already has an associated session before this filter is invoked, either because it
040 * was created in another part of the application, or a filter higher in the chain created one, this filter has no
041 * effect.
042 * </li>
043 * </ol>
044 * Finally, calls to <code>subject.getSession(false)</code> (i.e. a {@code false} boolean value) will be unaffected
045 * and may be called without repercussion in all cases.
046 *
047 * @since 1.2
048 */
049public class NoSessionCreationFilter extends PathMatchingFilter {
050
051    @Override
052    protected boolean onPreHandle(ServletRequest request, ServletResponse response, Object mappedValue) throws Exception {
053        request.setAttribute(DefaultSubjectContext.SESSION_CREATION_ENABLED, Boolean.FALSE);
054        return true;
055    }
056}