propertyutil.java

derby database source code.good for you.

/*

   Derby - Class org.apache.derby.iapi.util.PropertyUtil

   Copyright 1998, 2004 The Apache Software Foundation or its licensors, as applicable.

   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.derby.iapi.util;

import java.util.Properties;
import java.util.Enumeration;
import java.io.InputStream;
import java.io.IOException;

public class PropertyUtil {
	

	//////////////////////////////////////////////////////////////////////////////
	//
	//	SORTS A PROPERTY LIST AND STRINGIFIES THE SORTED PROPERTIES
	//
	/////////////////////////////////////////////////////////////////////////////

	/**
	  *	Sorts a property list and turns the sorted list into a string.
	  *
	  *	@param	list	property list to sort
	  *
	  *	@return	a string version of the sorted list
	  */
	public	static	String	sortProperties( Properties list )
	{
		// stringify them with no indentation
		return sortProperties(list, null);
	}

	/**
	 * Sorts property list and print out each key=value pair prepended with 
	 * specific indentation.  If indent is null, do not prepend with
	 * indentation. 
	 *
	 * The output string shows up in two styles, style 1 looks like
	 * { key1=value1, key2=value2, key3=value3 }
	 *
	 * style 2 looks like
	 *		key1=value1
	 *		key2=value2
	 *		key3=value3
	 * where indent goes between the new line and the keys
	 *
	 * To get style 1, pass in a null indent
	 * To get sytle 2, pass in non-null indent (whatever you want to go before
	 * the key value)
	 */
	public	static	String	sortProperties( Properties list, String indent )
	{
		int				size = list == null ? 0 : list.size();
		int				count = 0;
		String[]		array = new String[size];
		String			key;
		String			value;
		StringBuffer	buffer;

		// Calculate the number of properties in the property list and
		// build an array of all the property names.
		// We need to go thru the enumeration because Properties has a
		// recursive list of defaults.
		if (list != null)
		{
			for (Enumeration propertyNames = list.propertyNames();
				 propertyNames.hasMoreElements(); )
			{
				if (count == size)
				{
					// need to expand the array
					size = size*2;
					String[] expandedArray = new String[size];
					System.arraycopy(array, 0, expandedArray, 0, count);
					array = expandedArray;
				}
				key = (String) propertyNames.nextElement();
				array[ count++ ] = key;
			}

			// now sort the array
			java.util.Arrays.sort(array, 0, count);
		}

		// now stringify the array
		buffer = new StringBuffer();
		if (indent == null)
			buffer.append( "{ " );

		for ( int ictr = 0; ictr < count; ictr++ )
		{
			if ( ictr > 0 && indent == null)
				buffer.append( ", " );

			key = array[ ictr ];

			if (indent != null)
				buffer.append( indent );

			buffer.append( key ); buffer.append( "=" );

			value = list.getProperty( key, "MISSING_VALUE" );
			buffer.append( value );

			if (indent != null)
				buffer.append( "\n" );

		}
		if (indent == null)
			buffer.append( " }" );

		return	buffer.toString();
	}

    /**
     * Copy a set of properties from one Property to another.
     * <p>
     *
	 * @return The identifier to be used to open the conglomerate later.
     *
     * @param src_prop  Source set of properties to copy from.
     * @param dest_prop Dest Properties to copy into.
     *
     **/
    public static void copyProperties(Properties src_prop, Properties dest_prop)
    {
        for (Enumeration propertyNames = src_prop.propertyNames();
             propertyNames.hasMoreElements(); )
        {
            Object key = propertyNames.nextElement();
            dest_prop.put(key, src_prop.get(key));
        }
    }

	/** 
	 * Read a set of properties from the received input stream, strip
	 * off any excess white space that exists in those property values,
	 * and then add those newly-read properties to the received
	 * Properties object; not explicitly removing the whitespace here can
	 * lead to problems.
	 *
	 * This method exists because of the manner in which the jvm reads
	 * properties from file--extra spaces are ignored after a _key_, but
	 * if they exist at the _end_ of a property decl line (i.e. as part
	 * of a _value_), they are preserved, as outlined in the Java API:
	 *
	 * "Any whitespace after the key is skipped; if the first non-
	 * whitespace character after the key is = or :, then it is ignored
 	 * and any whitespace characters after it are also skipped. All
	 * remaining characters on the line become part of the associated
	 * element string."
	 *
	 * @iStr: An input stream from which the new properties are to be
	 *  loaded (should already be initialized).
	 * @param prop: A set of properties to which the properties from
	 *  iStr will be added (should already be initialized).
	 * @return A final properties set consisting of 'prop' plus all
	 * properties loaded from 'iStr' (with the extra whitespace (if any)
	 *  removed from all values), will be returned via the parameter.
	 *
	 **/
	public static void loadWithTrimmedValues(InputStream iStr,
		Properties prop) throws IOException {

		if ((iStr == null) || (prop == null)) {
		// shouldn't happen; just ignore this call and return.
			return;
		}

		// Else, load the properties from the received input stream.
		Properties p = new Properties();
		p.load(iStr);

		// Now, trim off any excess whitespace, if any, and then
		// add the properties from file to the received Properties
		// set.
		for (Enumeration propKeys = p.propertyNames();
		  propKeys.hasMoreElements();) {
		// get the value, trim off the whitespace, then store it
		// in the received properties object.
			String tmpKey = (String)propKeys.nextElement();
			String tmpValue = p.getProperty(tmpKey);
			tmpValue = tmpValue.trim();
			prop.put(tmpKey, tmpValue);
		}

		return;

	}
}