GUACAMOLE-275: Request browser to always revalidate cached index.html.

guacamole/src/main/java/org/apache/guacamole/CacheRevalidationFilter.java

@@ -0,0 +1,61 @@
+/*
+ * 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.guacamole;
+
+import java.io.IOException;
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * Filter that sets the HTTP response headers necessary to request that the
+ * browser always revalidate its cached copy of the response before using that
+ * cached copy.
+ */
+public class CacheRevalidationFilter implements Filter {
+
+    @Override
+    public void init(FilterConfig config) throws ServletException {
+        // No configuration
+    }
+
+    @Override
+    public void doFilter(ServletRequest request, ServletResponse response,
+            FilterChain chain) throws IOException, ServletException {
+
+        HttpServletResponse httpResponse = (HttpServletResponse) response;
+        httpResponse.addHeader("Cache-Control", "no-cache");
+        httpResponse.addHeader("Pragma", "no-cache");
+        
+        chain.doFilter(request, response);
+        
+    }
+
+    @Override
+    public void destroy() {
+        // Nothing to clean up
+    }
+
+
+}

guacamole/src/main/webapp/WEB-INF/web.xml

@@ -28,6 +28,16 @@
         <welcome-file>index.html</welcome-file>
     </welcome-file-list>
 
+    <!-- Request that the browser always revalidate its cached copy of index.html -->
+    <filter>
+        <filter-name>cacheRevalidationFilter</filter-name>
+        <filter-class>org.apache.guacamole.CacheRevalidationFilter</filter-class>
+    </filter>
+    <filter-mapping>
+        <filter-name>cacheRevalidationFilter</filter-name>
+        <url-pattern>/index.html</url-pattern>
+    </filter-mapping>
+
     <!-- Route all requests through Guice -->
     <filter>
         <filter-name>guiceFilter</filter-name>