1 /*
2 * Copyright 2002-2012 the original author or authors.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package org.springframework.web.context.request;
18
19 import javax.faces.context.FacesContext;
20
21 import org.springframework.core.NamedInheritableThreadLocal;
22 import org.springframework.core.NamedThreadLocal;
23 import org.springframework.util.ClassUtils;
24
25 /**
26 * Holder class to expose the web request in the form of a thread-bound
27 * {@link RequestAttributes} object. The request will be inherited
28 * by any child threads spawned by the current thread if the
29 * {@code inheritable} flag is set to {@code true}.
30 *
31 * <p>Use {@link RequestContextListener} or
32 * {@link org.springframework.web.filter.RequestContextFilter} to expose
33 * the current web request. Note that
34 * {@link org.springframework.web.servlet.DispatcherServlet} and
35 * {@link org.springframework.web.portlet.DispatcherPortlet} already
36 * expose the current request by default.
37 *
38 * @author Juergen Hoeller
39 * @author Rod Johnson
40 * @since 2.0
41 * @see RequestContextListener
42 * @see org.springframework.web.filter.RequestContextFilter
43 * @see org.springframework.web.servlet.DispatcherServlet
44 * @see org.springframework.web.portlet.DispatcherPortlet
45 */
46 public abstract class RequestContextHolder {
47
48 private static final boolean jsfPresent =
49 ClassUtils.isPresent("javax.faces.context.FacesContext", RequestContextHolder.class.getClassLoader());
50
51 private static final ThreadLocal<RequestAttributes> requestAttributesHolder =
52 new NamedThreadLocal<RequestAttributes>("Request attributes");
53
54 private static final ThreadLocal<RequestAttributes> inheritableRequestAttributesHolder =
55 new NamedInheritableThreadLocal<RequestAttributes>("Request context");
56
57
58 /**
59 * Reset the RequestAttributes for the current thread.
60 */
61 public static void resetRequestAttributes() {
62 requestAttributesHolder.remove();
63 inheritableRequestAttributesHolder.remove();
64 }
65
66 /**
67 * Bind the given RequestAttributes to the current thread,
68 * <i>not</i> exposing it as inheritable for child threads.
69 * @param attributes the RequestAttributes to expose
70 * @see #setRequestAttributes(RequestAttributes, boolean)
71 */
72 public static void setRequestAttributes(RequestAttributes attributes) {
73 setRequestAttributes(attributes, false);
74 }
75
76 /**
77 * Bind the given RequestAttributes to the current thread.
78 * @param attributes the RequestAttributes to expose,
79 * or {@code null} to reset the thread-bound context
80 * @param inheritable whether to expose the RequestAttributes as inheritable
81 * for child threads (using an {@link InheritableThreadLocal})
82 */
83 public static void setRequestAttributes(RequestAttributes attributes, boolean inheritable) {
84 if (attributes == null) {
85 resetRequestAttributes();
86 }
87 else {
88 if (inheritable) {
89 inheritableRequestAttributesHolder.set(attributes);
90 requestAttributesHolder.remove();
91 }
92 else {
93 requestAttributesHolder.set(attributes);
94 inheritableRequestAttributesHolder.remove();
95 }
96 }
97 }
98
99 /**
100 * Return the RequestAttributes currently bound to the thread.
101 * @return the RequestAttributes currently bound to the thread,
102 * or {@code null} if none bound
103 */
104 public static RequestAttributes getRequestAttributes() {
105 RequestAttributes attributes = requestAttributesHolder.get();
106 if (attributes == null) {
107 attributes = inheritableRequestAttributesHolder.get();
108 }
109 return attributes;
110 }
111
112 /**
113 * Return the RequestAttributes currently bound to the thread.
114 * <p>Exposes the previously bound RequestAttributes instance, if any.
115 * Falls back to the current JSF FacesContext, if any.
116 * @return the RequestAttributes currently bound to the thread
117 * @throws IllegalStateException if no RequestAttributes object
118 * is bound to the current thread
119 * @see #setRequestAttributes
120 * @see ServletRequestAttributes
121 * @see FacesRequestAttributes
122 * @see javax.faces.context.FacesContext#getCurrentInstance()
123 */
124 public static RequestAttributes currentRequestAttributes() throws IllegalStateException {
125 RequestAttributes attributes = getRequestAttributes();
126 if (attributes == null) {
127 if (jsfPresent) {
128 attributes = FacesRequestAttributesFactory.getFacesRequestAttributes();
129 }
130 if (attributes == null) {
131 throw new IllegalStateException("No thread-bound request found: " +
132 "Are you referring to request attributes outside of an actual web request, " +
133 "or processing a request outside of the originally receiving thread? " +
134 "If you are actually operating within a web request and still receive this message, " +
135 "your code is probably running outside of DispatcherServlet/DispatcherPortlet: " +
136 "In this case, use RequestContextListener or RequestContextFilter to expose the current request.");
137 }
138 }
139 return attributes;
140 }
141
142
143 /**
144 * Inner class to avoid hard-coded JSF dependency.
145 */
146 private static class FacesRequestAttributesFactory {
147
148 public static RequestAttributes getFacesRequestAttributes() {
149 FacesContext facesContext = FacesContext.getCurrentInstance();
150 return (facesContext != null ? new FacesRequestAttributes(facesContext) : null);
151 }
152 }
153
154 }