1 /**
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.activemq.web.filter;
18
19 import java.io.IOException;
20 import java.util.AbstractMap;
21 import java.util.Collections;
22 import java.util.Map;
23 import java.util.Set;
24
25 import javax.servlet.Filter;
26 import javax.servlet.FilterChain;
27 import javax.servlet.FilterConfig;
28 import javax.servlet.ServletContext;
29 import javax.servlet.ServletException;
30 import javax.servlet.ServletRequest;
31 import javax.servlet.ServletResponse;
32
33 import org.springframework.web.bind.ServletRequestDataBinder;
34 import org.springframework.web.context.WebApplicationContext;
35 import org.springframework.web.context.support.WebApplicationContextUtils;
36
37 /**
38 * Exposes Spring ApplicationContexts to JSP EL and other view technologies.
39 * Currently a variable is placed in application scope (by default called
40 * 'applicationContext') so that POJOs can be pulled out of Spring in a JSP page
41 * to render things using EL expressions. <br/>
42 *
43 * e.g. ${applicationContext.cheese} would access the cheese POJO. Or
44 * ${applicationContext.cheese.name} would access the name property of the
45 * cheese POJO. <br/>
46 *
47 * You can then use JSTL to work with these POJOs such as <c.set var="myfoo"
48 * value="${applicationContext.foo}"/> <br/>
49 *
50 * In addition to applicationContext a 'requestContext' variable is created
51 * which will automatically bind any request parameters to the POJOs extracted
52 * from the applicationContext - which is ideal for POJOs which implement
53 * queries in view technologies.
54 *
55 * @version $Revision: 565003 $
56 */
57 public class ApplicationContextFilter implements Filter {
58
59 private ServletContext servletContext;
60 private String applicationContextName = "applicationContext";
61 private String requestContextName = "requestContext";
62 private String requestName = "request";
63
64 public void init(FilterConfig config) throws ServletException {
65 this.servletContext = config.getServletContext();
66 this.applicationContextName = getInitParameter(config, "applicationContextName", applicationContextName);
67 this.requestContextName = getInitParameter(config, "requestContextName", requestContextName);
68 this.requestName = getInitParameter(config, "requestName", requestName);
69
70 // register the application context in the applicationScope
71 WebApplicationContext context = WebApplicationContextUtils.getWebApplicationContext(servletContext);
72 Map wrapper = createApplicationContextWrapper(context);
73 servletContext.setAttribute(applicationContextName, wrapper);
74 }
75
76 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
77 // lets register a requestContext in the requestScope
78 Map requestContextWrapper = createRequestContextWrapper(request);
79 request.setAttribute(requestContextName, requestContextWrapper);
80 request.setAttribute(requestName, request);
81 chain.doFilter(request, response);
82 }
83
84 public void destroy() {
85 }
86
87 public ServletContext getServletContext() {
88 return servletContext;
89 }
90
91 public String getApplicationContextName() {
92 return applicationContextName;
93 }
94
95 public void setApplicationContextName(String variableName) {
96 this.applicationContextName = variableName;
97 }
98
99 public String getRequestContextName() {
100 return requestContextName;
101 }
102
103 public void setRequestContextName(String requestContextName) {
104 this.requestContextName = requestContextName;
105 }
106
107 protected String getInitParameter(FilterConfig config, String key, String defaultValue) {
108 String parameter = config.getInitParameter(key);
109 return (parameter != null) ? parameter : defaultValue;
110 }
111
112 /**
113 * Creates a wrapper around the web application context so that it can be
114 * accessed easily from inside JSP EL (or other expression languages in
115 * other view technologies).
116 */
117 protected Map createApplicationContextWrapper(final WebApplicationContext context) {
118 Map wrapper = new AbstractMap() {
119
120 public WebApplicationContext getContext() {
121 return context;
122 }
123
124 public Object get(Object key) {
125 if (key == null) {
126 return null;
127 }
128 return context.getBean(key.toString());
129 }
130
131 public Set entrySet() {
132 return Collections.EMPTY_SET;
133 }
134
135 };
136 return wrapper;
137 }
138
139 /**
140 * Creates a wrapper around the request context (e.g. to allow POJOs to be
141 * auto-injected from request parameter values etc) so that it can be
142 * accessed easily from inside JSP EL (or other expression languages in
143 * other view technologies).
144 */
145 protected Map createRequestContextWrapper(final ServletRequest request) {
146 final WebApplicationContext context = WebApplicationContextUtils.getWebApplicationContext(servletContext);
147 Map wrapper = new AbstractMap() {
148
149 public WebApplicationContext getContext() {
150 return context;
151 }
152
153 public Object get(Object key) {
154 if (key == null) {
155 return null;
156 }
157 return bindRequestBean(context.getBean(key.toString()), request);
158 }
159
160 public Set entrySet() {
161 return Collections.EMPTY_SET;
162 }
163
164 };
165 return wrapper;
166
167 }
168
169 /**
170 * Binds properties from the request parameters to the given POJO which is
171 * useful for POJOs which are configurable via request parameters such as
172 * for query/view POJOs
173 */
174 protected Object bindRequestBean(Object bean, ServletRequest request) {
175 ServletRequestDataBinder binder = new ServletRequestDataBinder(bean, null);
176 binder.bind(request);
177 return bean;
178 }
179
180 }