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 */
019 package org.apache.shiro;
020
021 import org.apache.shiro.mgt.SecurityManager;
022 import org.apache.shiro.subject.Subject;
023 import org.apache.shiro.util.ThreadContext;
024
025
026 /**
027 * Accesses the currently accessible {@code Subject} for the calling code depending on runtime environment.
028 *
029 * @author Les Hazlewood
030 * @since 0.2
031 */
032 public abstract class SecurityUtils {
033
034 /**
035 * ONLY used as a 'backup' in VM Singleton environments (that is, standalone environments), since the
036 * ThreadContext should always be the primary source for Subject instances when possible.
037 */
038 private static SecurityManager securityManager;
039
040 /**
041 * Returns the currently accessible {@code Subject} available to the calling code depending on
042 * runtime environment.
043 * <p/>
044 * This method is provided as a way of obtaining a {@code Subject} without having to resort to
045 * implementation-specific methods. It also allows the Shiro team to change the underlying implementation of
046 * this method in the future depending on requirements/updates without affecting your code that uses it.
047 *
048 * @return the currently accessible {@code Subject} accessible to the calling code.
049 * @throws IllegalStateException if no {@link Subject Subject} instance or
050 * {@link SecurityManager SecurityManager} instance is available with which to obtain
051 * a {@code Subject}, which which is considered an invalid application configuration
052 * - a Subject should <em>always</em> be available to the caller.
053 */
054 public static Subject getSubject() {
055 Subject subject = ThreadContext.getSubject();
056 if (subject == null) {
057 subject = (new Subject.Builder()).buildSubject();
058 ThreadContext.bind(subject);
059 }
060 return subject;
061 }
062
063 /**
064 * Sets a VM (static) singleton SecurityManager, specifically for transparent use in the
065 * {@link #getSubject() getSubject()} implementation.
066 * <p/>
067 * <b>This method call exists mainly for framework development support. Application developers should rarely,
068 * if ever, need to call this method.</b>
069 * <p/>
070 * The Shiro development team prefers that SecurityManager instances are non-static application singletons
071 * and <em>not</em> VM static singletons. Application singletons that do not use static memory require some sort
072 * of application configuration framework to maintain the application-wide SecurityManager instance for you
073 * (for example, Spring or EJB3 environments) such that the object reference does not need to be static.
074 * <p/>
075 * In these environments, Shiro acquires Subject data based on the currently executing Thread via its own
076 * framework integration code, and this is the preferred way to use Shiro.
077 * <p/>
078 * However in some environments, such as a standalone desktop application or Applets that do not use Spring or
079 * EJB or similar config frameworks, a VM-singleton might make more sense (although the former is still preferred).
080 * In these environments, setting the SecurityManager via this method will automatically enable the
081 * {@link #getSubject() getSubject()} call to function with little configuration.
082 * <p/>
083 * For example, in these environments, this will work:
084 * <pre>
085 * DefaultSecurityManager securityManager = new {@link org.apache.shiro.mgt.DefaultSecurityManager DefaultSecurityManager}();
086 * securityManager.setRealms( ... ); //one or more Realms
087 * <b>SecurityUtils.setSecurityManager( securityManager );</b></pre>
088 * <p/>
089 * And then anywhere in the application code, the following call will return the application's Subject:
090 * <pre>
091 * Subject currentUser = SecurityUtils.getSubject();</pre>
092 *
093 * @param securityManager the securityManager instance to set as a VM static singleton.
094 */
095 public static void setSecurityManager(SecurityManager securityManager) {
096 SecurityUtils.securityManager = securityManager;
097 }
098
099 /**
100 * Returns the SecurityManager accessible to the calling code.
101 * <p/>
102 * This implementation favors acquiring a thread-bound {@code SecurityManager} if it can find one. If one is
103 * not available to the executing thread, it will attempt to use the static singleton if available (see the
104 * {@link #setSecurityManager setSecurityManager} method for more on the static singleton).
105 * <p/>
106 * If neither the thread-local or static singleton instances are available, this method throws an
107 * {@code UnavailableSecurityManagerException} to indicate an error - a SecurityManager should always be accessible
108 * to calling code in an application. If it is not, it is likely due to a Shiro configuration problem.
109 *
110 * @return the SecurityManager accessible to the calling code.
111 * @throws UnavailableSecurityManagerException
112 * if there is no {@code SecurityManager} instance available to the
113 * calling code, which typically indicates an invalid application configuration.
114 */
115 public static SecurityManager getSecurityManager() throws UnavailableSecurityManagerException {
116 SecurityManager securityManager = ThreadContext.getSecurityManager();
117 if (securityManager == null) {
118 securityManager = SecurityUtils.securityManager;
119 }
120 if (securityManager == null) {
121 String msg = "No SecurityManager accessible to the calling code, either bound to the " +
122 ThreadContext.class.getName() + " or as a vm static singleton. This is an invalid application " +
123 "configuration.";
124 throw new UnavailableSecurityManagerException(msg);
125 }
126 return securityManager;
127 }
128 }