implement WebResourceLoaders for loading plugin web resources

scm-webapp/src/main/java/sonia/scm/plugin/DefaultUberWebResourceLoader.java

@@ -0,0 +1,231 @@
+/**
+ * Copyright (c) 2014, Sebastian Sdorra All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer. 2. Redistributions in
+ * binary form must reproduce the above copyright notice, this list of
+ * conditions and the following disclaimer in the documentation and/or other
+ * materials provided with the distribution. 3. Neither the name of SCM-Manager;
+ * nor the names of its contributors may be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * http://bitbucket.org/sdorra/scm-manager
+ *
+ */
+
+
+
+package sonia.scm.plugin;
+
+//~--- non-JDK imports --------------------------------------------------------
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Throwables;
+import com.google.common.cache.Cache;
+import com.google.common.cache.CacheBuilder;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableList.Builder;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+//~--- JDK imports ------------------------------------------------------------
+
+import java.net.MalformedURLException;
+import java.net.URL;
+
+import java.util.List;
+
+import javax.servlet.ServletContext;
+
+/**
+ * Default implementation of the {@link UberWebResourceLoader}.
+ *
+ * @author Sebastian Sdorra
+ * @since 2.0.0
+ */
+public class DefaultUberWebResourceLoader implements UberWebResourceLoader
+{
+
+  /**
+   * the logger for DefaultUberWebResourceLoader
+   */
+  private static final Logger logger =
+    LoggerFactory.getLogger(DefaultUberWebResourceLoader.class);
+
+  //~--- constructors ---------------------------------------------------------
+
+  /**
+   * Constructs ...
+   *
+   *
+   * @param servletContext
+   * @param plugins
+   */
+  public DefaultUberWebResourceLoader(ServletContext servletContext,
+    Iterable<PluginWrapper> plugins)
+  {
+    this.servletContext = servletContext;
+    this.plugins = plugins;
+    this.cache = CacheBuilder.newBuilder().build();
+  }
+
+  //~--- get methods ----------------------------------------------------------
+
+  /**
+   * Method description
+   *
+   *
+   * @param path
+   *
+   * @return
+   */
+  @Override
+  public URL getResource(String path)
+  {
+    URL resource = cache.getIfPresent(path);
+
+    if (resource == null)
+    {
+      resource = find(path);
+
+      if (resource != null)
+      {
+        cache.put(path, resource);
+      }
+    }
+    else
+    {
+      logger.trace("return web resource {} from cache", path);
+    }
+
+    return resource;
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @param path
+   *
+   * @return
+   */
+  @Override
+  public List<URL> getResources(String path)
+  {
+
+    // caching ???
+    Builder<URL> resources = ImmutableList.builder();
+
+    try
+    {
+      URL ctxResource = servletContext.getResource(path);
+
+      if (ctxResource != null)
+      {
+        logger.trace("found path {} at ServletContext", path);
+        resources.add(ctxResource);
+      }
+
+      for (PluginWrapper wrapper : plugins)
+      {
+        URL resource = wrapper.getWebResourceLoader().getResource(path);
+
+        if (resource != null)
+        {
+          resources.add(resource);
+        }
+      }
+    }
+    catch (MalformedURLException ex)
+    {
+
+      // TODO define an extra exception
+      throw Throwables.propagate(ex);
+    }
+
+    return resources.build();
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @return
+   */
+  @VisibleForTesting
+  Cache<String, URL> getCache()
+  {
+    return cache;
+  }
+
+  //~--- methods --------------------------------------------------------------
+
+  /**
+   * Method description
+   *
+   *
+   * @param path
+   *
+   * @return
+   */
+  private URL find(String path)
+  {
+    URL resource = null;
+
+    try
+    {
+      resource = servletContext.getResource(path);
+
+      if (resource == null)
+      {
+        for (PluginWrapper wrapper : plugins)
+        {
+          resource = wrapper.getWebResourceLoader().getResource(path);
+
+          if (resource != null)
+          {
+            break;
+          }
+        }
+      }
+      else
+      {
+        logger.trace("found path {} at ServletContext", path);
+      }
+    }
+    catch (MalformedURLException ex)
+    {
+
+      // TODO define an extra exception
+      throw Throwables.propagate(ex);
+    }
+
+    return resource;
+  }
+
+  //~--- fields ---------------------------------------------------------------
+
+  /** Field description */
+  private final Cache<String, URL> cache;
+
+  /** Field description */
+  private final Iterable<PluginWrapper> plugins;
+
+  /** Field description */
+  private final ServletContext servletContext;
+}