svn commit: r689664 - /velocity/tools/trunk/src/main/java/org/apache/velocity/tools/view/VelocityViewFilter.java

[nb...@apache.org]

Author: nbubna
Date: Wed Aug 27 16:31:54 2008
New Revision: 689664

URL: http://svn.apache.org/viewvc?rev=689664&view=rev
Log:
initial revision of VelocityViewFilter

Added:
    velocity/tools/trunk/src/main/java/org/apache/velocity/tools/view/VelocityViewFilter.java   (with props)

Added: velocity/tools/trunk/src/main/java/org/apache/velocity/tools/view/VelocityViewFilter.java
URL: http://svn.apache.org/viewvc/velocity/tools/trunk/src/main/java/org/apache/velocity/tools/view/VelocityViewFilter.java?rev=689664&view=auto
==============================================================================
--- velocity/tools/trunk/src/main/java/org/apache/velocity/tools/view/VelocityViewFilter.java (added)
+++ velocity/tools/trunk/src/main/java/org/apache/velocity/tools/view/VelocityViewFilter.java Wed Aug 27 16:31:54 2008
@@ -0,0 +1,191 @@
+package org.apache.velocity.tools.view;
+
+/*
+ * 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.
+ */
+
+import java.io.IOException;
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletContext;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import org.apache.velocity.context.Context;
+import org.apache.velocity.tools.view.VelocityView;
+import org.apache.velocity.tools.view.ViewToolContext;
+
+/**
+ * <p>A filter to ensure VelocityTools {@link Toolbox}es are
+ * available in the request/session/application scopes. This
+ * can simplify the process of integration with other frameworks.</p>
+ *
+ * <p>VelocityViewFilter supports the following configuration parameters
+ * in web.xml:</p>
+ * <dl>
+ *   <dt>org.apache.velocity.tools</dt>
+ *   <dd>Path and name of the toolbox configuration file. The path must be
+ *     relative to the web application root directory. If this parameter is
+ *     not found, the servlet will check for a toolbox file at
+ *     '/WEB-INF/tools.xml'.</dd>
+ *   <dt>org.apache.velocity.properties</dt>
+ *   <dd>Path and name of the Velocity configuration file. The path must be
+ *     relative to the web application root directory. If this parameter
+ *     is not present, Velocity will check for a properties file at
+ *     '/WEB-INF/velocity.properties'.  If no file is found there, then
+ *     Velocity is initialized with the settings in the classpath at
+ *     'org.apache.velocity.tools.view.velocity.properties'.</dd>
+ *   <dt>org.apache.velocity.tools.loadDefaults</dt>
+ *   <dd>By default, this is {@code true}. If set to {@code false}, then
+ *     the default toolbox configuration will not be added to your (if any)
+ *     custom configuration.  NOTE: The default configuration will also be
+ *     suppressed if you are using a deprecated toolbox.xml format and do not
+ *     explicitly set this to {@code true}.</dd>
+ *   <dt>org.apache.velocity.tools.cleanConfiguration</dt>
+ *   <dd>By default, this is {@code false}. If set to {@code true}, then
+ *     then the final toolbox configuration (the combination of any custom
+ *     one(s) provided by yourself and/or the default configuration(s))
+ *     will have all invalid tools, properties, and/or data removed prior to
+ *     configuring the ToolboxFactory for this servlet by a
+ *     {@link org.apache.velocity.tools.config.ConfigurationCleaner}</dd>
+ *   <dt>org.apache.velocity.tools.shared.config</dt>
+ *   <dd>By default, this is {@code true}. If set to {@code false}, then
+ *     the {@link VelocityView} used by this filter will not be shared
+ *     with other VelocityViewFilters, {@link VelocityViewServlet}s or 
+ *     {@link org.apache.velocity.tools.view.jsp.VelocityViewTag}s in the
+ *     application.</dd>
+ *   <dt>org.apache.velocity.tools.context.key</dt>
+ *   <dd>If you set a value for this property, this filter will create
+ *     and prepare a {@link ViewToolContext} for each request, and then
+ *     place it into the request attributes under the key you set. This
+ *     is primarily for those who have this filter NOT share a config
+ *     (i.e. non-shared VelocityView) and thus will find it easier to
+ *     retrieve a working context from the request attributes than it
+ *     would be to get the VelocityView for this filter and have it
+ *     create the context for them.  Most users will have no trouble
+ *     getting a shared VelocityView and creating the context themselves.</dd>
+ * </dl>
+ *
+ * @version $Id: VelocityViewFilter.java 611011 2008-01-11 01:32:59Z nbubna $
+ */
+public class VelocityViewFilter implements Filter
+{
+    public static final String CONTEXT_KEY =
+        "org.apache.velocity.tools.context.key";
+
+    private VelocityView view;
+    private FilterConfig config;
+    private String contextKey = null;
+
+    /**
+     * <p>Initializes VelocityView used to process requests.
+     * Called by the servlet container on loading.</p>
+     *
+     * @param config filter configuation
+     */
+    public void init(FilterConfig config) throws ServletException
+    {
+        this.config = config;
+
+        // init the VelocityView (if it hasn't been already)
+        getVelocityView();
+
+        // look for a context key
+        contextKey = findInitParameter(CONTEXT_KEY);
+    }
+
+    protected FilterConfig getFilterConfig()
+    {
+        return this.config;
+    }
+
+    protected VelocityView getVelocityView()
+    {
+        if (this.view == null)
+        {
+            this.view = ServletUtils.getVelocityView(getFilterConfig());
+            assert (view != null);
+        }
+        return this.view;
+    }
+
+    protected String getContextKey()
+    {
+        return this.contextKey;
+    }
+
+    /**
+     * Looks up an init parameter with the specified key in either the
+     * FilterConfig or, failing that, in the ServletContext.
+     */
+    protected String findInitParameter(String key)
+    {
+        FilterConfig conf = getFilterConfig();
+        String param = conf.getInitParameter(key);
+        if (param == null || param.length() == 0)
+        {
+            param = conf.getServletContext().getInitParameter(key);
+        }
+        return param;
+    }
+
+    /**
+     * Simply prepares the request (and/or session) toolbox(es)
+     * for other filters, servlets or whatnot to use.  If a context key
+     * has been provided in the init-params of the filter or webapp,
+     * then this will also create a {@link ViewToolContext} and put
+     * it in the request attributes under that key.
+     */
+    public void doFilter(ServletRequest request,
+                         ServletResponse response,
+                         FilterChain chain)
+        throws java.io.IOException, ServletException
+    {
+        // prepare toolbox(es)
+        getVelocityView().prepareToolboxes(request);
+
+        // can/should we create the context for the request?
+        if (contextKey != null && request instanceof HttpServletRequest)
+        {
+            Context context = createContext((HttpServletRequest)request,
+                                            (HttpServletResponse)response);
+            request.setAttribute(contextKey, context);
+        }
+
+        // move down the chain
+        chain.doFilter(request, response);
+    }
+
+    protected Context createContext(HttpServletRequest request,
+                                    HttpServletResponse response)
+    {
+        return getVelocityView().createContext(request, response);
+    }
+
+    public void destroy()
+    {
+        // do anything else?
+        this.view = null;
+        this.config = null;
+        this.contextKey = null;
+    }
+
+}

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