ThreadContext.java
/*
* 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.shiro.util;
import org.apache.shiro.mgt.SecurityManager;
import org.apache.shiro.subject.Subject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
/**
* A ThreadContext provides a means of binding and unbinding objects to the
* current thread based on key/value pairs.
* <p/>
* <p>An internal {@link java.util.HashMap} is used to maintain the key/value pairs
* for each thread.</p>
* <p/>
* <p>If the desired behavior is to ensure that bound data is not shared across
* threads in a pooled or reusable threaded environment, the application (or more likely a framework) must
* bind and remove any necessary values at the beginning and end of stack
* execution, respectively (i.e. individually explicitly or all via the <tt>clear</tt> method).</p>
*
* @see #remove()
* @since 0.1
*/
public abstract class ThreadContext {
/**
* Private internal log instance.
*/
private static final Logger log = LoggerFactory.getLogger(ThreadContext.class);
public static final String SECURITY_MANAGER_KEY = ThreadContext.class.getName() + "_SECURITY_MANAGER_KEY";
public static final String SUBJECT_KEY = ThreadContext.class.getName() + "_SUBJECT_KEY";
private static final ThreadLocal<Map<Object, Object>> resources = new InheritableThreadLocalMap<Map<Object, Object>>();
/**
* Default no-argument constructor.
*/
protected ThreadContext() {
}
/**
* Returns the ThreadLocal Map. This Map is used internally to bind objects
* to the current thread by storing each object under a unique key.
*
* @return the map of bound resources
*/
public static Map<Object, Object> getResources() {
if (resources.get() == null){
return Collections.emptyMap();
} else {
return new HashMap<Object, Object>(resources.get());
}
}
/**
* Allows a caller to explicitly set the entire resource map. This operation overwrites everything that existed
* previously in the ThreadContext - if you need to retain what was on the thread prior to calling this method,
* call the {@link #getResources()} method, which will give you the existing state.
*
* @param newResources the resources to replace the existing {@link #getResources() resources}.
* @since 1.0
*/
public static void setResources(Map<Object, Object> newResources) {
if (CollectionUtils.isEmpty(newResources)) {
return;
}
ensureResourcesInitialized();
resources.get().clear();
resources.get().putAll(newResources);
}
/**
* Returns the value bound in the {@code ThreadContext} under the specified {@code key}, or {@code null} if there
* is no value for that {@code key}.
*
* @param key the map key to use to lookup the value
* @return the value bound in the {@code ThreadContext} under the specified {@code key}, or {@code null} if there
* is no value for that {@code key}.
* @since 1.0
*/
private static Object getValue(Object key) {
Map<Object, Object> perThreadResources = resources.get();
return perThreadResources != null ? perThreadResources.get(key) : null;
}
private static void ensureResourcesInitialized(){
if (resources.get() == null){
resources.set(new HashMap<Object, Object>());
}
}
/**
* Returns the object for the specified <code>key</code> that is bound to
* the current thread.
*
* @param key the key that identifies the value to return
* @return the object keyed by <code>key</code> or <code>null</code> if
* no value exists for the specified <code>key</code>
*/
public static Object get(Object key) {
if (log.isTraceEnabled()) {
String msg = "get() - in thread [" + Thread.currentThread().getName() + "]";
log.trace(msg);
}
Object value = getValue(key);
if ((value != null) && log.isTraceEnabled()) {
String msg = "Retrieved value of type [" + value.getClass().getName() + "] for key [" +
key + "] " + "bound to thread [" + Thread.currentThread().getName() + "]";
log.trace(msg);
}
return value;
}
/**
* Binds <tt>value</tt> for the given <code>key</code> to the current thread.
* <p/>
* <p>A <tt>null</tt> <tt>value</tt> has the same effect as if <tt>remove</tt> was called for the given
* <tt>key</tt>, i.e.:
* <p/>
* <pre>
* if ( value == null ) {
* remove( key );
* }</pre>
*
* @param key The key with which to identify the <code>value</code>.
* @param value The value to bind to the thread.
* @throws IllegalArgumentException if the <code>key</code> argument is <tt>null</tt>.
*/
public static void put(Object key, Object value) {
if (key == null) {
throw new IllegalArgumentException("key cannot be null");
}
if (value == null) {
remove(key);
return;
}
ensureResourcesInitialized();
resources.get().put(key, value);
if (log.isTraceEnabled()) {
String msg = "Bound value of type [" + value.getClass().getName() + "] for key [" +
key + "] to thread " + "[" + Thread.currentThread().getName() + "]";
log.trace(msg);
}
}
/**
* Unbinds the value for the given <code>key</code> from the current
* thread.
*
* @param key The key identifying the value bound to the current thread.
* @return the object unbound or <tt>null</tt> if there was nothing bound
* under the specified <tt>key</tt> name.
*/
public static Object remove(Object key) {
Map<Object, Object> perThreadResources = resources.get();
Object value = perThreadResources != null ? perThreadResources.remove(key) : null;
if ((value != null) && log.isTraceEnabled()) {
String msg = "Removed value of type [" + value.getClass().getName() + "] for key [" +
key + "]" + "from thread [" + Thread.currentThread().getName() + "]";
log.trace(msg);
}
return value;
}
/**
* {@link ThreadLocal#remove Remove}s the underlying {@link ThreadLocal ThreadLocal} from the thread.
* <p/>
* This method is meant to be the final 'clean up' operation that is called at the end of thread execution to
* prevent thread corruption in pooled thread environments.
*
* @since 1.0
*/
public static void remove() {
resources.remove();
}
/**
* Convenience method that simplifies retrieval of the application's SecurityManager instance from the current
* thread. If there is no SecurityManager bound to the thread (probably because framework code did not bind it
* to the thread), this method returns <tt>null</tt>.
* <p/>
* It is merely a convenient wrapper for the following:
* <p/>
* <code>return (SecurityManager)get( SECURITY_MANAGER_KEY );</code>
* <p/>
* This method only returns the bound value if it exists - it does not remove it
* from the thread. To remove it, one must call {@link #unbindSecurityManager() unbindSecurityManager()} instead.
*
* @return the Subject object bound to the thread, or <tt>null</tt> if there isn't one bound.
* @since 0.9
*/
public static SecurityManager getSecurityManager() {
return (SecurityManager) get(SECURITY_MANAGER_KEY);
}
/**
* Convenience method that simplifies binding the application's SecurityManager instance to the ThreadContext.
* <p/>
* <p>The method's existence is to help reduce casting in code and to simplify remembering of
* ThreadContext key names. The implementation is simple in that, if the SecurityManager is not <tt>null</tt>,
* it binds it to the thread, i.e.:
* <p/>
* <pre>
* if (securityManager != null) {
* put( SECURITY_MANAGER_KEY, securityManager);
* }</pre>
*
* @param securityManager the application's SecurityManager instance to bind to the thread. If the argument is
* null, nothing will be done.
* @since 0.9
*/
public static void bind(SecurityManager securityManager) {
if (securityManager != null) {
put(SECURITY_MANAGER_KEY, securityManager);
}
}
/**
* Convenience method that simplifies removal of the application's SecurityManager instance from the thread.
* <p/>
* The implementation just helps reduce casting and remembering of the ThreadContext key name, i.e it is
* merely a convenient wrapper for the following:
* <p/>
* <code>return (SecurityManager)remove( SECURITY_MANAGER_KEY );</code>
* <p/>
* If you wish to just retrieve the object from the thread without removing it (so it can be retrieved later
* during thread execution), use the {@link #getSecurityManager() getSecurityManager()} method instead.
*
* @return the application's SecurityManager instance previously bound to the thread, or <tt>null</tt> if there
* was none bound.
* @since 0.9
*/
public static SecurityManager unbindSecurityManager() {
return (SecurityManager) remove(SECURITY_MANAGER_KEY);
}
/**
* Convenience method that simplifies retrieval of a thread-bound Subject. If there is no
* Subject bound to the thread, this method returns <tt>null</tt>. It is merely a convenient wrapper
* for the following:
* <p/>
* <code>return (Subject)get( SUBJECT_KEY );</code>
* <p/>
* This method only returns the bound value if it exists - it does not remove it
* from the thread. To remove it, one must call {@link #unbindSubject() unbindSubject()} instead.
*
* @return the Subject object bound to the thread, or <tt>null</tt> if there isn't one bound.
* @since 0.2
*/
public static Subject getSubject() {
return (Subject) get(SUBJECT_KEY);
}
/**
* Convenience method that simplifies binding a Subject to the ThreadContext.
* <p/>
* <p>The method's existence is to help reduce casting in your own code and to simplify remembering of
* ThreadContext key names. The implementation is simple in that, if the Subject is not <tt>null</tt>,
* it binds it to the thread, i.e.:
* <p/>
* <pre>
* if (subject != null) {
* put( SUBJECT_KEY, subject );
* }</pre>
*
* @param subject the Subject object to bind to the thread. If the argument is null, nothing will be done.
* @since 0.2
*/
public static void bind(Subject subject) {
if (subject != null) {
put(SUBJECT_KEY, subject);
}
}
/**
* Convenience method that simplifies removal of a thread-local Subject from the thread.
* <p/>
* The implementation just helps reduce casting and remembering of the ThreadContext key name, i.e it is
* merely a convenient wrapper for the following:
* <p/>
* <code>return (Subject)remove( SUBJECT_KEY );</code>
* <p/>
* If you wish to just retrieve the object from the thread without removing it (so it can be retrieved later during
* thread execution), you should use the {@link #getSubject() getSubject()} method for that purpose.
*
* @return the Subject object previously bound to the thread, or <tt>null</tt> if there was none bound.
* @since 0.2
*/
public static Subject unbindSubject() {
return (Subject) remove(SUBJECT_KEY);
}
private static final class InheritableThreadLocalMap<T extends Map<Object, Object>> extends InheritableThreadLocal<Map<Object, Object>> {
/**
* This implementation was added to address a
* <a href="http://jsecurity.markmail.org/search/?q=#query:+page:1+mid:xqi2yxurwmrpqrvj+state:results">
* user-reported issue</a>.
* @param parentValue the parent value, a HashMap as defined in the {@link #initialValue()} method.
* @return the HashMap to be used by any parent-spawned child threads (a clone of the parent HashMap).
*/
@SuppressWarnings({"unchecked"})
protected Map<Object, Object> childValue(Map<Object, Object> parentValue) {
if (parentValue != null) {
return (Map<Object, Object>) ((HashMap<Object, Object>) parentValue).clone();
} else {
return null;
}
}
}
}