propertieshelper.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): C.J. Hurst ([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.util;


import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

import java.util.Enumeration;
import java.util.MissingResourceException;
import java.util.Properties;
import java.util.ResourceBundle;

import org.apache.log4j.Category;


/**
 * This class consists of convenience methods for using properties files.
 * It allows for dynamic loading of properties throughout the life
 * of the web application.
 *
 */
public class PropertiesHelper
  {

  public static final Category LOG =
            Category.getInstance(PropertiesHelper.class.getName());

  // Empty constructor
  public PropertiesHelper()
    {
    }

  /**
   * loadProperties is used to retrieve a Properties object consisting of the
   * passed-in filename.  If there are any errors in loading the Properties
   * file, null will be returned.
   *
   * @param String - The name of the properties file to load
   * @return Properties - The Properties object consisting of all the
   *                      key/value pairs for the file
   */
  public static Properties loadProperties(String filename)
    {
    if ( filename != null )
        {
        return PropertiesHelper.loadProperties(new File(filename));
        }
    else
        {
        return null;
        }
    }

  /**
   * loadProperties is used to retrieve a Properties object consisting of the
   * passed-in file.  If there are any errors in loading the Properties file,
   * null will be returned.
   *
   * @param File - The properties file to load
   * @return Properties - The Properties object consisting of all the
   *                      key/value pairs for the file
   */
  public static Properties loadProperties(File file)
    {
    Properties result = null;

    // load as a Properties Object
    // handle errors if file not found.
    if (file != null)
        {
        FileInputStream is = null;
        try
            {
            // create input stream to read from file
            is = new FileInputStream(file);

            // load the Properties
            result = new Properties();
            result.load(is);
            }
        catch (FileNotFoundException e)
            {
            // FileInputStream() - if file not found
            LOG.error(
                "Unable to find/load file: " + file.getPath(),
                e);
            result = null;
            }
        catch (SecurityException e)
            {
            // FileInputStream() - if not allowed to read file
            LOG.error(
                "Unable to read file: " + file.getPath(),
                e);
            result = null;
            }
        catch (IOException e)
            {
            // Properties().load() - while reading the file
            LOG.error(
                "Error reading file: " + file.getPath(),
                e);
            result = null;
            }
        finally
            {
            if (is != null)
                {
                // have to close the file, to allow file
                // system changing of the file.
                try
                    {
                    is.close();
                    }
                catch (IOException e)
                    {
                    LOG.error(
                        "Error closing file: " + file.getPath(),
                        e);
                    } // catch
                }
            } // finally
        }

    return result;
    } // loadProperties()


  /**
   *  This static method takes information from a resourceBundle and builds
   *  a properties object from the key-value pairs.
   *
   *  @param String - the name of the Resource bundle to be read in
   *  @return Properties - populated with information from the resource bundle
   *                       or return null if no bundle is found
   */
  public static Properties getPropertiesForBundle(String bundleName)
    {
    Properties props = new Properties();
    try
        {
        ResourceBundle bundle = ResourceBundle.getBundle(bundleName);
        Enumeration enum = bundle.getKeys();
        while ( enum.hasMoreElements() )
            {
            String key = (String)enum.nextElement();
            props.put(key,bundle.getString(key));
            System.out.println(key + ", " + bundle.getString(key));
            }
        }
    catch ( MissingResourceException ex )
        {
        StringBuffer sb = new StringBuffer();
        sb.append("Warning, Properties file not found for bundle ");
        sb.append(bundleName);
        if ( bundleName.endsWith(".properties") )
            {
            sb.append("(probably because you placed '.properties' ");
            sb.append("at the end of the bundle name)");
            }
        LOG.warn(sb.toString());
        props = null;
        }
    return props;
    }


  } // PropertiesHelper