jrfproperties.java

把java对象映射成数据库表中的一条记录

/*
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
 * License for the specific language governing rights and limitations under
 * the License.
 *
 * The Original Code is jRelationalFramework.
 *
 * The Initial Developer of the Original Code is is.com.
 * Portions created by is.com are Copyright (C) 2000 is.com.
 * All Rights Reserved.
 *
 * Contributor(s): Jonathan Carlson ([e-mail])
 * Contributor(s): ____________________________________
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License (the "GPL") or the GNU Lesser General
 * Public license (the "LGPL"), in which case the provisions of the GPL or
 * LGPL are applicable instead of those above.  If you wish to allow use of
 * your version of this file only under the terms of either the GPL or LGPL
 * and not to allow others to use your version of this file under the MPL,
 * indicate your decision by deleting the provisions above and replace them
 * with the notice and other provisions required by either the GPL or LGPL
 * License.  If you do not delete the provisions above, a recipient may use
 * your version of this file under either the MPL or GPL or LGPL License.
 *
 */
package com.is.jrf;


import com.is.jrf.DatabasePolicy;
import com.is.jrf.InstantDBDatabasePolicy;
import com.is.jrf.OracleDatabasePolicy;
import com.is.jrf.SQLServerSybaseDatabasePolicy;
import com.is.jrf.HypersonicDatabasePolicy;

import com.is.util.PropertiesHelper;

import java.util.Properties;

import org.apache.log4j.Category;


/**
 *  Use of this class or it's properties file is <i>not</i> required.  This
 *  class is used only when the AbstractDomain subclass has not set a
 *  DatabasePolicy or JDBCHelper information.
 *
 *  <p> This class manages the properties file for the jRelationalFramework.
 *
 *  <p> The location of the properties file can be set with the
 *  <code>-DjrfPropertiesFile=</code> JVM argument.  Otherwise, the default
 *  is assumed to be <code>jrf.properties</jrf> somewhere in the root of one
 *  of the directories (or jars) in the classpath.
 *
 */
public class JRFProperties
  {

  private static Properties     s_properties = null;
  private static DatabasePolicy s_databasePolicy = null;
  /** See java.util.ResourceBundle */
  private static final String   DEFAULT_BUNDLE_NAME = "jrf";
  private static boolean        s_bundleNotFound = false;
  private static final Category LOG =
                Category.getInstance(JRFProperties.class.getName());

  /**
   * Check the jrfPropertiesFile system property (set with a jvm argument of
   * <code>-DjrfPropertiesFile=abc</code> -- The ".properties" file suffix is
   * assumed).  If there is no property with that name, we assume the
   * properties file is named <code>jrf.properties</code> and is in the root
   * of one of the directories (or jars) in the classpath.
   */
  public static void initialize()
    {
    String bundleName = System.getProperty("jrfPropertiesFile");
    if (bundleName != null)
        {
        int index = bundleName.indexOf(".properties");
        if (index > 0)
            {
            bundleName = bundleName.substring(0, index);
            }
        }
    else
        {
        bundleName = DEFAULT_BUNDLE_NAME;
        }
    JRFProperties.initialize(bundleName);
    } // initialize()


  /**
   * To use this method, there must be a <i>bundleName</i>.properties file
   * somewhere in the classpath.  Note that understanding how
   * java.util.ResourceBundle works will help in understanding how this
   * works.
   *
   * @param bundleName a value of type 'String'.  See java.util.ResourceBundle
   */
  public static synchronized void initialize(String bundleName)
    {
    // if we've alrady been here and not found the properties file bundle,
    // then don't look for it again.
    if (s_bundleNotFound)
        {
        return;
        }
    s_properties = PropertiesHelper.getPropertiesForBundle(bundleName);
    if (s_properties == null)
        {
        s_bundleNotFound = true;
        LOG.warn(
            "com.is.jrf.JRFProperties could not find the "
            + bundleName + ".properties file.  This may be by design.");
        return;
        }
    else
        {
        LOG.info(
            "JRFProperties initialized with resource bundle named '"
            + bundleName + "'");
        }

    // Set the static s_databasePolicy field.
    JRFProperties.assignDatabasePolicy();
    } // initialize(aString)


  public static synchronized void initialize(Properties properties)
    {
    s_properties = properties;
    } // initialize(aProperties)


  /**
   * If the first time, then read the properties file.  Return the value of
   * the specified property.
   *
   * @param aString a value of type 'String'
   * @return a value of type 'String'
   */
  public static String getProperty(String aString)
    {
    if (s_properties == null)
        {
        JRFProperties.initialize();
        }
    if (s_properties == null)
        {
        return null;
        }
    return s_properties.getProperty(aString);
    }


  /**
   * Return true if the property exists and it's value is "true" or "yes".
   * The default is false if the property does not exist.
   *
   * @return a value of type 'boolean'
   */
  public static boolean propertyIsTrue(String aString)
    {
    String value = JRFProperties.getProperty(aString);
    boolean returnValue = false;
    if (value != null &&
        (value.equalsIgnoreCase("true") ||
         value.equalsIgnoreCase("yes")))
        {
        returnValue = true;
        }
    return returnValue;
    }


  /**
   * Return the DatabasePolicy instance.  Be warned that if this database
   * policy object has instance variables and you are in a multi-threaded
   * environment, that this instance may need to be synchronized or else
   * this will need to return a clone of the database policy.
   *
   * @return a value of type 'DatabasePolicy'
   */
  public static DatabasePolicy getDatabasePolicy()
    {
    if (s_properties == null)
        {
        JRFProperties.initialize();
        }
    return s_databasePolicy;
    } // getDatabasePolicy()


  /**
   * Depending upon the databasePolicy value in the properties file, create
   * an instance of a subclass of DatabasePolicy and assign it to its'
   * static field.
   */
  private static void assignDatabasePolicy()
    {
    String policyClass = JRFProperties.getProperty("databasePolicy");
    if (policyClass == null)
    {
        return;
    }
    try
        {
        s_databasePolicy =
                (DatabasePolicy) Class.forName(policyClass).newInstance();
        }
    catch (Exception e)
        {
        throw new ConfigurationException(e);
        }
    } // assignDatabasePolicy()


  } // JRFProperties