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From m..@apache.org
Subject svn commit: r424813 - in /db/jdo/trunk/util20: project.xml src/java/org/apache/jdo/util/web/ src/java/org/apache/jdo/util/web/JDOFilter.java
Date Sun, 23 Jul 2006 20:49:34 GMT
Author: mbo
Date: Sun Jul 23 13:49:34 2006
New Revision: 424813

URL: http://svn.apache.org/viewvc?rev=424813&view=rev
Log:
JDO-398: Add servlet Filter utility class managing a PersistenceManager per request

Added:
    db/jdo/trunk/util20/src/java/org/apache/jdo/util/web/
    db/jdo/trunk/util20/src/java/org/apache/jdo/util/web/JDOFilter.java
Modified:
    db/jdo/trunk/util20/project.xml

Modified: db/jdo/trunk/util20/project.xml
URL: http://svn.apache.org/viewvc/db/jdo/trunk/util20/project.xml?rev=424813&r1=424812&r2=424813&view=diff
==============================================================================
--- db/jdo/trunk/util20/project.xml (original)
+++ db/jdo/trunk/util20/project.xml Sun Jul 23 13:49:34 2006
@@ -36,9 +36,19 @@
     <!-- ============ -->
     <dependencies>
         <dependency>
+            <groupId>javax.jdo</groupId>
+            <artifactId>jdo2-api</artifactId>
+            <version>SNAPSHOT</version>
+        </dependency>
+        <dependency>
             <groupId>commons-logging</groupId>
             <artifactId>commons-logging</artifactId>
             <version>1.1</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.geronimo.specs</groupId>
+            <artifactId>geronimo-servlet_2.4_spec</artifactId>
+            <version>1.0.1</version>
         </dependency>
     </dependencies>
     <!-- =================== -->

Added: db/jdo/trunk/util20/src/java/org/apache/jdo/util/web/JDOFilter.java
URL: http://svn.apache.org/viewvc/db/jdo/trunk/util20/src/java/org/apache/jdo/util/web/JDOFilter.java?rev=424813&view=auto
==============================================================================
--- db/jdo/trunk/util20/src/java/org/apache/jdo/util/web/JDOFilter.java (added)
+++ db/jdo/trunk/util20/src/java/org/apache/jdo/util/web/JDOFilter.java Sun Jul 23 13:49:34
2006
@@ -0,0 +1,288 @@
+/*
+ * Copyright 2006 The Apache Software Foundation.
+ * 
+ * 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 org.apache.jdo.util.web;
+
+import java.io.InputStream;
+import java.io.IOException;
+
+import javax.jdo.JDOHelper;
+import javax.jdo.PersistenceManagerFactory;
+import javax.jdo.PersistenceManager;
+
+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 org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+/** 
+ * This implementation of the servlet Filter interface creates a JDO 
+ * PersistenceManager, stores it as a request attribute and as a ThreadLocal. 
+ * It closes the PersistenceManager after the filter chain has returned.
+ * The idea for this class is taken from the JavaOne 2003 presentation 
+ * "Using Struts with Java Data Objects" by Craig Russell, Craig McClanahan
+ * and Amy Roh.
+ * <p>
+ * To setup the filter add the following to your deployment descriptor:
+ * <pre>
+ * &lt;filter&gt;
+ *     &lt;filter-name&gt;JDOFilter&lt;/filter-name&gt;
+ *     &lt;filter-class&gt;org.apache.jdo.util.web.JDOFilter&lt;/filter-class&gt;
+ * &lt;/filter&gt;
+ * &lt;filter-mapping&gt;
+ *     &lt;filter-name&gt;JDOFilter&lt;/filter-name&gt;
+ *     &lt;url-pattern&gt;/*&lt;/url-pattern&gt;
+ * &lt;/filter-mapping&gt;
+ * </pre>
+ * The JDOFilter supports two filter initialization paramters:
+ * <ul>
+ * <li><code>pmfPropsResource</code>: the name of the PersistenceManagerFactory
+ * properties resource. Default is <code>/WEB-INF/pmf.properties</code>.</li>
+ * <li><code>pmRequestAttrName</code>: the name of the request attribute
used to
+ * store the PersistenceManager instance. Default is <code>jdoPM</code>.
+ * </ul>
+ * This is an sample filter definition using initialization parameter:
+ * <pre>
+ * &lt;filter&gt;
+ *     &lt;filter-name&gt;JDOFilter&lt;/filter-name&gt;
+ *     &lt;filter-class&gt;org.apache.jdo.util.web.JDOFilter&lt;/filter-class&gt;
+ *     &lt;init-param&gt;
+ *         &lt;param-name&gt;pmfPropsResource&lt;/param-name&gt;
+ *         &lt;param-value&gt;/WEB-INF/pmf.properties&lt;/param-value&gt;
+ *     &lt;/init-param&gt;
+ *     &lt;init-param&gt;
+ *         &lt;param-name&gt;pmRequestAttrName&lt;/param-name&gt;
+ *         &lt;param-value&gt;jdoPM&lt;/param-value&gt;
+ *     &lt;/init-param&gt;
+ * &lt;/filter&gt;
+ * </pre>
+ * It is possible to define multiple filters in the deployment descriptor, all 
+ * using the JDOFilter class. In this case it is important to specify the name 
+ * of the PersistenceManager request attribute in the filter configuration by 
+ * setting the pmRequestAttrName initialization paramter. Otherwise, the 
+ * different filter instances would try to use the same request attribute. 
+ * Please note, in case of multiple JDOFilter instances, only the first filter 
+ * stores its PersistenceManager as a ThreadLocal. 
+ * <p>
+ * The static method {@link #getThreadLocalPM()} allows retrieving the 
+ * PersistenceManager instance bound to the current thread.
+ */
+public class JDOFilter
+    implements Filter  {
+
+    /** The name of the JDOFilter initialization parameter allowing to specify 
+     * the name of the pmf properties resource. */
+    public static final String PMF_PROPS_RESOURCE_PARAM = "pmfPropsResource";
+
+    /** The default PMF properties resource. */
+    public static final String PMF_PROPS_RESOURCE_DEFAULT = 
+        "/WEB-INF/pmf.properties";
+    
+    /** The name of the JDOFilter initialization parameter allowing to specify 
+     * the name of the pm request attribute.  */
+    public static final String PM_REQUEST_ATTR_NAME_PARAM = "pmRequestAttrName";
+    
+    /** The name of the request attribute storing the PersistenceManager. */
+    public static final String PM_REQUEST_ATTR_NAME_DEFAULT = "jdoPM";
+
+    /** The ThreadLocal storing the PersistenceManager. */
+    private static ThreadLocal pmThreadLocal = new ThreadLocal();
+    
+    /** Logging support. */
+    private static final Log logger = LogFactory.getLog(JDOFilter.class);
+        
+    /** The PMF instance created by the init method. */
+    private PersistenceManagerFactory pmf;
+    
+    /** The name of the request attribute holding the PersistenceManager. */
+    private String pmRequestAttrName;
+        
+    // ===== javax.servlet.Filter methods =====
+
+    /** Called by the web container to indicate to a filter that it is being 
+     * placed into service. 
+     * <p>
+     * This implementation creates a JDO PersistenceManagerFactory instance 
+     * using a properties resource specified by an initialization parameter 
+     * called {@link #PMF_PROPS_RESOURCE_PARAM} or defaulted to 
+     * {@link #PMF_PROPS_RESOURCE_DEFAULT}. The method checks for another 
+     * initialization parameter {@link #PM_REQUEST_ATTR_NAME_PARAM} that may be
+     * used to specify the name of the request attribute holding the 
+     * PersistenceManager instance. The name defaults to 
+     * {@link #PM_REQUEST_ATTR_NAME_DEFAULT} if there is no such initialization
+     * parameter.
+     * @param filterConfig the filter configuration object. 
+     */
+    public void init(FilterConfig filterConfig) throws ServletException {
+        String pmfPropsResource = 
+            filterConfig.getInitParameter(PMF_PROPS_RESOURCE_PARAM);
+        boolean usingPMFPropsResourceDefault = false;
+        if ((pmfPropsResource == null) || pmfPropsResource.length() == 0) {
+            pmfPropsResource = PMF_PROPS_RESOURCE_DEFAULT;
+            usingPMFPropsResourceDefault = true;
+        }
+        ServletContext context = filterConfig.getServletContext();
+        InputStream stream = context.getResourceAsStream(pmfPropsResource);
+        if (stream == null) {
+            ServletException ex = new ServletException(
+                "Error during initialization of JDOFilter: " + 
+                "Cannot find JDO PMF properties resource " +
+                (usingPMFPropsResourceDefault ? "defaulted to " : "") +
+                pmfPropsResource);
+            throw ex;
+        }
+        pmf = JDOHelper.getPersistenceManagerFactory(stream);
+        if (logger.isDebugEnabled()) {
+            logger.debug(
+                "Created PMF " + pmf +
+                "\nPMF properties: " +
+                "\n\t driver         = " + pmf.getConnectionDriverName() + 
+                "\n\t URL            = " + pmf.getConnectionURL() + 
+                "\n\t userName       = " + pmf.getConnectionUserName() + 
+                "\n\t mapping        = " + pmf.getMapping() +
+                "\n\t optimistic     = " + pmf.getOptimistic() +
+                "\n\t retainValues   = " + pmf.getRetainValues() +
+                "\n\t restoreValues  = " + pmf.getRestoreValues() +
+                "\n\t nonTxRead      = " + pmf.getNontransactionalRead() +
+                "\n\t nonTxWrite     = " + pmf.getNontransactionalWrite() +
+                "\n\t ignoreCache    = " + pmf.getIgnoreCache() +
+                "\n\t detachOnCommit = " + pmf.getDetachAllOnCommit() +
+                "\n\t properties     = " + pmf.getProperties());
+        }
+
+        // get the name of the request attribute holding the PersistenceManager
+        pmRequestAttrName = 
+            filterConfig.getInitParameter(PM_REQUEST_ATTR_NAME_PARAM);
+        if ((pmRequestAttrName == null) || pmRequestAttrName.length() == 0) {
+            pmRequestAttrName = PM_REQUEST_ATTR_NAME_DEFAULT;
+        }
+    }
+
+    /** The doFilter method of the Filter is called by the container each time a
+     * request/response pair is passed through the chain due to a client request
+     * for a resource at the end of the chain. This implementation creates a 
+     * PersistenceManager, stores it as a request attribute and in a ThreadLocal
+     * and then calls the filter chain. It closes the PersistenceManager after 
+     * the chain returns.
+     * @param request the resquest
+     * @param response the response 
+     * @param chain the filter chain   
+     */
+    public void doFilter(ServletRequest request, ServletResponse response, 
+                         FilterChain chain) 
+        throws IOException, ServletException {
+        PersistenceManager pm = null;
+        try {
+            pm = initializePM(request);
+            if (logger.isDebugEnabled()) {
+                logger.debug("Created PM " + pm);
+            }
+            chain.doFilter(request, response);
+        } finally {
+            if (logger.isDebugEnabled()) {
+                logger.debug("Close PM " + pm);
+            }
+            finalizePM(request, pm);
+        }
+    }
+
+    /** Called by the web container to indicate to a filter that it is being 
+     * taken out of service. This implementation closes the 
+     * PersistenceManagerFactory. 
+     */
+    public void destroy() {
+        if (pmf != null) {
+            if (logger.isDebugEnabled()) {
+                logger.debug("Close PMF " + pmf);
+            }
+            pmf.close();
+            pmf = null;
+        }
+    }
+    
+    // ===== Public methods not defined in Filter =====
+    
+    /** Returns the PersistenceManager instance bound to the current thread 
+     * using a ThreadLocal. 
+     * @return the PersistenceManager bound to the current thread.
+     */
+    public static PersistenceManager getThreadLocalPM() {
+         return (PersistenceManager)pmThreadLocal.get();
+    }
+    
+    // ===== Internal helper methods =====
+
+    /** Helper method to create and store a new PersistenceManager. The method 
+     * stores the PersistenceManager as value of the request attribute denoted 
+     * by {@link #pmRequestAttrName} and in a ThreadLocal. Use static method
+     * {@link #getThreadLocalPM()} to retrieve the PersistenceManager instance 
+     * bound to the current thread.
+     * @param request the request to store in the PersistenceManager as 
+     * attribute.
+     * @return a new PersistenceManager
+     */
+    private PersistenceManager initializePM(ServletRequest request) 
+        throws ServletException {
+        PersistenceManager pm = pmf.getPersistenceManager();
+        if (request.getAttribute(pmRequestAttrName) != null) {
+            ServletException ex = new ServletException(
+                "JDOFilter: error during PM intialization, request attribute " +
+                pmRequestAttrName + " already defined as " + 
+                 request.getAttribute(pmRequestAttrName));
+            throw ex;
+        }
+        request.setAttribute(pmRequestAttrName, pm);
+        if (pmThreadLocal.get() == null) {
+            pmThreadLocal.set(pm);
+        }
+        return pm;
+    }    
+
+    /** Helper method to finalize a PersistenceManager. The method closes the 
+     * specified PersistenceManager. If there is an active transaction it is 
+     * rolled back before the PersistenceManager is closed. The method also 
+     * removes the request attribute holding a PersistenceManager and nullifies
+     * the ThreadLocal value, but only if it is the specified 
+     * PersistenceManager.
+     * @param request the request holding the PersistenceManager as attribute.
+     * @param the PersistenceManager
+     */
+    private void finalizePM(ServletRequest request, PersistenceManager pm) {
+        if (pm == null) {
+            return;
+        }
+        if (!pm.isClosed()) {
+            if (pm.currentTransaction().isActive()) {
+                pm.currentTransaction().rollback();
+            }
+            pm.close();
+        }
+        // Remove request attribute if it is the specified pm
+        if (request.getAttribute(pmRequestAttrName) == pm) {
+            request.removeAttribute(pmRequestAttrName);
+        }
+        // Nullify the thread local if it is the specified pm
+        if (pmThreadLocal.get() == pm) {
+            pmThreadLocal.set(null);
+        }
+    }
+
+}



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