1 files changed, 106 insertions, 0 deletions
diff --git a/gerrit-gwtexpui/src/main/java/com/google/gwtexpui/server/CacheControlFilter.java b/gerrit-gwtexpui/src/main/java/com/google/gwtexpui/server/CacheControlFilter.java
new file mode 100644
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+++ b/gerrit-gwtexpui/src/main/java/com/google/gwtexpui/server/CacheControlFilter.java
@@ -0,0 +1,106 @@
+// Copyright (C) 2008 The Android Open Source Project
+//
+// Licensed 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 com.google.gwtexpui.server;
+
+import java.io.IOException;
+import java.util.concurrent.TimeUnit;
+
+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.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * Forces GWT resources to cache for a very long time.
+ * <p>
+ * GWT compiled JavaScript and ImageBundles can be cached indefinitely by a
+ * browser and/or an edge proxy, as they never contain user-specific data and
+ * are named by a unique checksum. If their content is ever modified then the
+ * URL changes, so user agents would request a different resource. We force
+ * these resources to have very long expiration times.
+ * <p>
+ * To use, add the following block to your <code>web.xml</code>:
+ *
+ * <pre>
+ * &lt;filter&gt;
+ *     &lt;filter-name&gt;CacheControl&lt;/filter-name&gt;
+ *     &lt;filter-class&gt;com.google.gwtexpui.server.CacheControlFilter&lt;/filter-class&gt;
+ *   &lt;/filter&gt;
+ *   &lt;filter-mapping&gt;
+ *     &lt;filter-name&gt;CacheControl&lt;/filter-name&gt;
+ *     &lt;url-pattern&gt;/*&lt;/url-pattern&gt;
+ *   &lt;/filter-mapping&gt;
+ * </pre>
+ */
+public class CacheControlFilter implements Filter {
+  public void init(final FilterConfig config) {
+  }
+
+  public void destroy() {
+  }
+
+  public void doFilter(final ServletRequest sreq, final ServletResponse srsp,
+      final FilterChain chain) throws IOException, ServletException {
+    final HttpServletRequest req = (HttpServletRequest) sreq;
+    final HttpServletResponse rsp = (HttpServletResponse) srsp;
+    final String pathInfo = pathInfo(req);
+
+    if (cacheForever(pathInfo, req)) {
+      CacheHeaders.setCacheable(req, rsp, 365, TimeUnit.DAYS);
+    } else if (nocache(pathInfo)) {
+      CacheHeaders.setNotCacheable(rsp);
+    }
+
+    chain.doFilter(req, rsp);
+  }
+
+  private static boolean cacheForever(final String pathInfo,
+      final HttpServletRequest req) {
+    if (pathInfo.endsWith(".cache.html")) {
+      return true;
+    } else if (pathInfo.endsWith(".cache.gif")) {
+      return true;
+    } else if (pathInfo.endsWith(".cache.png")) {
+      return true;
+    } else if (pathInfo.endsWith(".cache.css")) {
+      return true;
+    } else if (pathInfo.endsWith(".cache.jar")) {
+      return true;
+    } else if (pathInfo.endsWith(".cache.swf")) {
+      return true;
+    } else if (pathInfo.endsWith(".nocache.js")) {
+      final String v = req.getParameter("content");
+      return v != null && v.length() > 20;
+    }
+    return false;
+  }
+
+  private static boolean nocache(final String pathInfo) {
+    if (pathInfo.endsWith(".nocache.js")) {
+      return true;
+    }
+    return false;
+  }
+
+  private static String pathInfo(final HttpServletRequest req) {
+    final String uri = req.getRequestURI();
+    final String ctx = req.getContextPath();
+    return uri.startsWith(ctx) ? uri.substring(ctx.length()) : uri;
+  }
+}