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.servlet.handler;
18
19 import org.springframework.beans.BeansException;
20 import org.springframework.beans.factory.BeanFactoryUtils;
21 import org.springframework.context.ApplicationContextException;
22 import org.springframework.util.ObjectUtils;
23
24 /**
25 * Abstract implementation of the {@link org.springframework.web.servlet.HandlerMapping}
26 * interface, detecting URL mappings for handler beans through introspection of all
27 * defined beans in the application context.
28 *
29 * @author Juergen Hoeller
30 * @since 2.5
31 * @see #determineUrlsForHandler
32 */
33 public abstract class AbstractDetectingUrlHandlerMapping extends AbstractUrlHandlerMapping {
34
35 private boolean detectHandlersInAncestorContexts = false;
36
37
38 /**
39 * Set whether to detect handler beans in ancestor ApplicationContexts.
40 * <p>Default is "false": Only handler beans in the current ApplicationContext
41 * will be detected, i.e. only in the context that this HandlerMapping itself
42 * is defined in (typically the current DispatcherServlet's context).
43 * <p>Switch this flag on to detect handler beans in ancestor contexts
44 * (typically the Spring root WebApplicationContext) as well.
45 */
46 public void setDetectHandlersInAncestorContexts(boolean detectHandlersInAncestorContexts) {
47 this.detectHandlersInAncestorContexts = detectHandlersInAncestorContexts;
48 }
49
50
51 /**
52 * Calls the {@link #detectHandlers()} method in addition to the
53 * superclass's initialization.
54 */
55 @Override
56 public void initApplicationContext() throws ApplicationContextException {
57 super.initApplicationContext();
58 detectHandlers();
59 }
60
61 /**
62 * Register all handlers found in the current ApplicationContext.
63 * <p>The actual URL determination for a handler is up to the concrete
64 * {@link #determineUrlsForHandler(String)} implementation. A bean for
65 * which no such URLs could be determined is simply not considered a handler.
66 * @throws org.springframework.beans.BeansException if the handler couldn't be registered
67 * @see #determineUrlsForHandler(String)
68 */
69 protected void detectHandlers() throws BeansException {
70 if (logger.isDebugEnabled()) {
71 logger.debug("Looking for URL mappings in application context: " + getApplicationContext());
72 }
73 String[] beanNames = (this.detectHandlersInAncestorContexts ?
74 BeanFactoryUtils.beanNamesForTypeIncludingAncestors(getApplicationContext(), Object.class) :
75 getApplicationContext().getBeanNamesForType(Object.class));
76
77 // Take any bean name that we can determine URLs for.
78 for (String beanName : beanNames) {
79 String[] urls = determineUrlsForHandler(beanName);
80 if (!ObjectUtils.isEmpty(urls)) {
81 // URL paths found: Let's consider it a handler.
82 registerHandler(urls, beanName);
83 }
84 else {
85 if (logger.isDebugEnabled()) {
86 logger.debug("Rejected bean name '" + beanName + "': no URL paths identified");
87 }
88 }
89 }
90 }
91
92
93 /**
94 * Determine the URLs for the given handler bean.
95 * @param beanName the name of the candidate bean
96 * @return the URLs determined for the bean,
97 * or {@code null} or an empty array if none
98 */
99 protected abstract String[] determineUrlsForHandler(String beanName);
100
101 }