--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/buildframework/helium/sf/java/jpa/src/com/nokia/helium/jpa/ORMReader.java	Tue Apr 27 08:33:08 2010 +0300
@@ -0,0 +1,127 @@
+
+/*
+ * Copyright (c) 2007-2008 Nokia Corporation and/or its subsidiary(-ies).
+ * All rights reserved.
+ * This component and the accompanying materials are made available
+ * under the terms of the License "Eclipse Public License v1.0"
+ * which accompanies this distribution, and is available
+ * at the URL "http://www.eclipse.org/legal/epl-v10.html".
+ *
+ * Initial Contributors:
+ * Nokia Corporation - initial contribution.
+ *
+ * Contributors:
+ *
+ * Description:  
+ *
+ */
+
+package com.nokia.helium.jpa;
+
+
+import org.apache.log4j.Logger;
+import java.util.List;
+import javax.persistence.Query;
+
+/**
+ * This class provides an interface to read data from the 
+ * database using JPA.
+ */
+public class ORMReader {
+
+    private static Logger log = Logger.getLogger(ORMReader.class);
+    
+    private static final int READ_CACHE_LIMIT = 30000;
+
+    private ORMEntityManager manager;
+    
+    private int startPos;
+
+    /**Constructor:
+     * @param dbPath - path of the database to connect to.
+     */
+    public ORMReader(String dbPath) {
+        ORMUtil.initializeORM(dbPath);
+        manager = ORMUtil.getEntityManager(dbPath);
+    }
+
+    /**
+     * Executes native sql query and returns List of objects
+     * of return type mentioned by type.
+     * @param queryString - sql query to be executed.
+     * @param type - return type.
+     * @return List of objects of return type.
+     */
+    public List executeNativeQuery(String queryString, String type) {
+        int maxResults = READ_CACHE_LIMIT;
+        String queryWithSubSet = queryString + " OFFSET " + startPos +
+                " ROWS FETCH FIRST " + maxResults + " ROW ONLY";
+        Query query = null;
+        if (type != null) {
+            try {
+                query = manager.getEntityManager().createNativeQuery(queryWithSubSet,
+                        Class.forName(type));
+            } catch (ClassNotFoundException ex) {
+                log.debug("Exception during native query", ex);
+            }
+        } else {
+            query = manager.getEntityManager().createNativeQuery(queryWithSubSet);
+        }
+        query.setHint("eclipselink.maintain-cache", "false");
+        List results = query.getResultList();
+        int resultsSize = results.size();
+        if (resultsSize == 0 || resultsSize < READ_CACHE_LIMIT) {
+            startPos += resultsSize;
+        } else {
+            startPos += maxResults;
+        }
+        return results;
+    }
+
+    /**
+     * Executes sql query which results in single result.
+     * @param queryString - sql query to be executed.
+     * @param type - return type.
+     * @return an Object of return type.
+     */
+    public Object  executeSingleResult(String queryString, String type) {
+        log.debug("executeSingleResult: " + queryString);
+        Query query = manager.getEntityManager().createQuery(queryString);
+        query.setHint("eclipselink.persistence-context.reference-mode", "WEAK");
+        query.setHint("eclipselink.maintain-cache", "false");
+        query.setHint("eclipselink.read-only", "true");
+        Object obj = null;
+        try {
+            obj = query.getSingleResult();
+        } catch (javax.persistence.NoResultException nex) {
+            log.debug("no results:", nex);
+        } catch (javax.persistence.NonUniqueResultException nux) {
+            log.debug("more than one result returned:", nux);
+        }
+        return obj;
+    }
+
+    /**
+     * Executes query using JPQL.
+     * @param queryString - jpa query string
+     * @return List of objects read from database.
+     */
+    public List executeQuery (String queryString) {
+        int maxResults = READ_CACHE_LIMIT;
+        Query query = manager.getEntityManager().createQuery(queryString);
+        query.setHint("eclipselink.persistence-context.reference-mode", "WEAK");
+        query.setHint("eclipselink.maintain-cache", "false");
+        query.setHint("eclipselink.read-only", "true");
+        query.setFirstResult(startPos);
+        query.setMaxResults(maxResults);
+        List results = (List) query.getResultList();
+        int resultsSize = results.size();
+        log.debug("result size: " + resultsSize);
+        if (results.size() == 0 || resultsSize < READ_CACHE_LIMIT) {
+            startPos += resultsSize;
+        } else {
+            startPos += maxResults;
+        }
+        return results;
+    }
+}
\ No newline at end of file