Coverage Report

 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You 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.commons.configuration;
 
 import java.io.File;
 import java.io.FilterWriter;
 import java.io.IOException;
 import java.io.LineNumberReader;
 import java.io.Reader;
 import java.io.Writer;
 import java.net.URL;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 
 import org.apache.commons.lang.ArrayUtils;
 import org.apache.commons.lang.StringEscapeUtils;
 import org.apache.commons.lang.StringUtils;
 
 /**
  * This is the "classic" Properties loader which loads the values from
  * a single or multiple files (which can be chained with "include =".
  * All given path references are either absolute or relative to the
  * file name supplied in the constructor.
  * <p>
  * In this class, empty PropertyConfigurations can be built, properties
  * added and later saved. include statements are (obviously) not supported
  * if you don't construct a PropertyConfiguration from a file.
  *
  * <p>The properties file syntax is explained here, basically it follows
  * the syntax of the stream parsed by {@link java.util.Properties#load} and
  * adds several useful extensions:
  *
  * <ul>
  *  <li>
  *   Each property has the syntax <code>key &lt;separator> value</code>. The
  *   separators accepted are <code>'='</code>, <code>':'</code> and any white
  *   space character. Examples:
  * <pre>
  *  key1 = value1
  *  key2 : value2
  *  key3   value3</pre>
  *  </li>
  *  <li>
  *   The <i>key</i> may use any character, separators must be escaped:
  * <pre>
  *  key\:foo = bar</pre>
  *  </li>
  *  <li>
  *   <i>value</i> may be separated on different lines if a backslash
  *   is placed at the end of the line that continues below.
  *  </li>
  *  <li>
  *   <i>value</i> can contain <em>value delimiters</em> and will then be interpreted
  *   as a list of tokens. Default value delimiter is the comma ','. So the
  *   following property definition
  * <pre>
  *  key = This property, has multiple, values
  * </pre>
  *   will result in a property with three values. You can change the value
  *   delimiter using the <code>{@link AbstractConfiguration#setListDelimiter(char)}</code>
  *   method. Setting the delimiter to 0 will disable value splitting completely.
  *  </li>
  *  <li>
  *   Commas in each token are escaped placing a backslash right before
  *   the comma.
  *  </li>
  *  <li>
  *   If a <i>key</i> is used more than once, the values are appended
  *   like if they were on the same line separated with commas.
  *  </li>
  *  <li>
  *   Blank lines and lines starting with character '#' or '!' are skipped.
  *  </li>
  *  <li>
  *   If a property is named "include" (or whatever is defined by
  *   setInclude() and getInclude() and the value of that property is
  *   the full path to a file on disk, that file will be included into
  *   the configuration. You can also pull in files relative to the parent
  *   configuration file. So if you have something like the following:
  *
  *   include = additional.properties
  *
  *   Then "additional.properties" is expected to be in the same
  *   directory as the parent configuration file.
  *
  *   The properties in the included file are added to the parent configuration,
  *   they do not replace existing properties with the same key.
  *
  *  </li>
  * </ul>
  *
  * <p>Here is an example of a valid extended properties file:
  *
  * <p><pre>
  *      # lines starting with # are comments
  *
  *      # This is the simplest property
  *      key = value
  *
  *      # A long property may be separated on multiple lines
  *      longvalue = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa \
  *                  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
  *
  *      # This is a property with many tokens
  *      tokens_on_a_line = first token, second token
  *
  *      # This sequence generates exactly the same result
  *      tokens_on_multiple_lines = first token
  *      tokens_on_multiple_lines = second token
  *
  *      # commas may be escaped in tokens
  *      commas.escaped = Hi\, what'up?
  *
  *      # properties can reference other properties
  *      base.prop = /base
  *      first.prop = ${base.prop}/first
  *      second.prop = ${first.prop}/second
  * </pre>
  *
  * <p>A <code>PropertiesConfiguration</code> object is associated with an
  * instance of the <code>{@link PropertiesConfigurationLayout}</code> class,
  * which is responsible for storing the layout of the parsed properties file
  * (i.e. empty lines, comments, and such things). The <code>getLayout()</code>
  * method can be used to obtain this layout object. With <code>setLayout()</code>
  * a new layout object can be set. This should be done before a properties file
  * was loaded.
  *
  * @see java.util.Properties#load
  *
  * @author <a href="mailto:stefano@apache.org">Stefano Mazzocchi</a>
  * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a>
  * @author <a href="mailto:daveb@miceda-data">Dave Bryson</a>
  * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
  * @author <a href="mailto:leon@opticode.co.za">Leon Messerschmidt</a>
  * @author <a href="mailto:kjohnson@transparent.com">Kent Johnson</a>
  * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
  * @author <a href="mailto:ipriha@surfeu.fi">Ilkka Priha</a>
  * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
  * @author <a href="mailto:mpoeschl@marmot.at">Martin Poeschl</a>
  * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
  * @author <a href="mailto:epugh@upstate.com">Eric Pugh</a>
  * @author <a href="mailto:oliver.heger@t-online.de">Oliver Heger</a>
  * @author <a href="mailto:ebourg@apache.org">Emmanuel Bourg</a>
  * @version $Id: PropertiesConfiguration.java 439648 2006-09-02 20:42:10Z oheger $
  */
 public class PropertiesConfiguration extends AbstractFileConfiguration
 {
     /** Constant for the supported comment characters.*/
     static final String COMMENT_CHARS = "#!";
 
     /**
      * This is the name of the property that can point to other
      * properties file for including other properties files.
      */
     private static String include = "include";
 
     /** The list of possible key/value separators */
     private static final char[] SEPARATORS = new char[] {'=', ':'};
 
     /** The white space characters used as key/value separators. */
     private static final char[] WHITE_SPACE = new char[]{' ', '\t', '\f'};
 
     /**
      * The default encoding (ISO-8859-1 as specified by
      * http://java.sun.com/j2se/1.5.0/docs/api/java/util/Properties.html)
      */
     private static final String DEFAULT_ENCODING = "ISO-8859-1";
 
     /** Constant for the platform specific line separator.*/
     private static final String LINE_SEPARATOR = System.getProperty("line.separator");
 
     /** Constant for the radix of hex numbers.*/
     private static final int HEX_RADIX = 16;
 
     /** Constant for the length of a unicode literal.*/
     private static final int UNICODE_LEN = 4;
 
     /** Stores the layout object.*/
     private PropertiesConfigurationLayout layout;
 
     /** Allow file inclusion or not */
     private boolean includesAllowed;
 
     // initialization block to set the encoding before loading the file in the constructors
     {
         setEncoding(DEFAULT_ENCODING);
     }
 
     /**
      * Creates an empty PropertyConfiguration object which can be
      * used to synthesize a new Properties file by adding values and
      * then saving().
      */
     public PropertiesConfiguration()
     {
         layout = createLayout();
         setIncludesAllowed(false);
     }
 
     /**
      * Creates and loads the extended properties from the specified file.
      * The specified file can contain "include = " properties which then
      * are loaded and merged into the properties.
      *
      * @param fileName The name of the properties file to load.
      * @throws ConfigurationException Error while loading the properties file
      */
     public PropertiesConfiguration(String fileName) throws ConfigurationException
     {
         super(fileName);
     }
 
     /**
      * Creates and loads the extended properties from the specified file.
      * The specified file can contain "include = " properties which then
      * are loaded and merged into the properties.
      *
      * @param file The properties file to load.
      * @throws ConfigurationException Error while loading the properties file
      */
     public PropertiesConfiguration(File file) throws ConfigurationException
     {
         super(file);
     }
 
     /**
      * Creates and loads the extended properties from the specified URL.
      * The specified file can contain "include = " properties which then
      * are loaded and merged into the properties.
      *
      * @param url The location of the properties file to load.
      * @throws ConfigurationException Error while loading the properties file
      */
     public PropertiesConfiguration(URL url) throws ConfigurationException
     {
         super(url);
     }
 
     /**
      * Gets the property value for including other properties files.
      * By default it is "include".
      *
      * @return A String.
      */
     public static String getInclude()
     {
         return PropertiesConfiguration.include;
     }
 
     /**
      * Sets the property value for including other properties files.
      * By default it is "include".
      *
      * @param inc A String.
      */
     public static void setInclude(String inc)
     {
         PropertiesConfiguration.include = inc;
     }
 
     /**
      * Controls whether additional files can be loaded by the include = <xxx>
      * statement or not. Base rule is, that objects created by the empty
      * C'tor can not have included files.
      *
      * @param includesAllowed includesAllowed True if Includes are allowed.
      */
     protected void setIncludesAllowed(boolean includesAllowed)
     {
         this.includesAllowed = includesAllowed;
     }
 
     /**
      * Reports the status of file inclusion.
      *
      * @return True if include files are loaded.
      */
     public boolean getIncludesAllowed()
     {
         return this.includesAllowed;
     }
 
     /**
      * Return the comment header.
      *
      * @return the comment header
      * @since 1.1
      */
     public String getHeader()
     {
         return getLayout().getHeaderComment();
     }
 
     /**
      * Set the comment header.
      *
      * @param header the header to use
      * @since 1.1
      */
     public void setHeader(String header)
     {
         getLayout().setHeaderComment(header);
     }
 
     /**
      * Returns the associated layout object.
      *
      * @return the associated layout object
      * @since 1.3
      */
     public synchronized PropertiesConfigurationLayout getLayout()
     {
         if (layout == null)
         {
             layout = createLayout();
         }
         return layout;
     }
 
     /**
      * Sets the associated layout object.
      *
      * @param layout the new layout object; can be <b>null</b>, then a new
      * layout object will be created
      * @since 1.3
      */
     public synchronized void setLayout(PropertiesConfigurationLayout layout)
     {
         // only one layout must exist
         if (this.layout != null)
         {
             removeConfigurationListener(this.layout);
         }
 
         if (layout == null)
         {
             this.layout = createLayout();
         }
         else
         {
             this.layout = layout;
         }
     }
 
     /**
      * Creates the associated layout object. This method is invoked when the
      * layout object is accessed and has not been created yet. Derived classes
      * can override this method to hook in a different layout implementation.
      *
      * @return the layout object to use
      * @since 1.3
      */
     protected PropertiesConfigurationLayout createLayout()
     {
         return new PropertiesConfigurationLayout(this);
     }
 
     /**
      * Load the properties from the given reader.
      * Note that the <code>clear()</code> method is not called, so
      * the properties contained in the loaded file will be added to the
      * actual set of properties.
      *
      * @param in An InputStream.
      *
      * @throws ConfigurationException if an error occurs
      */
     public synchronized void load(Reader in) throws ConfigurationException
     {
         boolean oldAutoSave = isAutoSave();
         setAutoSave(false);
 
         try
         {
             getLayout().load(in);
         }
         finally
         {
             setAutoSave(oldAutoSave);
         }
     }
 
     /**
      * Save the configuration to the specified stream.
      *
      * @param writer the output stream used to save the configuration
      * @throws ConfigurationException if an error occurs
      */
     public void save(Writer writer) throws ConfigurationException
     {
         enterNoReload();
         try
         {
             getLayout().save(writer);
         }
         finally
         {
             exitNoReload();
         }
     }
 
     /**
      * Extend the setBasePath method to turn includes
      * on and off based on the existence of a base path.
      *
      * @param basePath The new basePath to set.
      */
     public void setBasePath(String basePath)
     {
         super.setBasePath(basePath);
         setIncludesAllowed(StringUtils.isNotEmpty(basePath));
     }
 
     /**
      * Creates a copy of this object.
      *
      * @return the copy
      */
     public Object clone()
     {
         PropertiesConfiguration copy = (PropertiesConfiguration) super.clone();
         if (layout != null)
         {
             copy.setLayout(new PropertiesConfigurationLayout(copy, layout));
         }
         return copy;
     }
 
     /**
      * This method is invoked by the associated
      * <code>{@link PropertiesConfigurationLayout}</code> object for each
      * property definition detected in the parsed properties file. Its task is
      * to check whether this is a special property definition (e.g. the
      * <code>include</code> property). If not, the property must be added to
      * this configuration. The return value indicates whether the property
      * should be treated as a normal property. If it is <b>false</b>, the
      * layout object will ignore this property.
      *
      * @param key the property key
      * @param value the property value
      * @return a flag whether this is a normal property
      * @throws ConfigurationException if an error occurs
      * @since 1.3
      */
     boolean propertyLoaded(String key, String value)
             throws ConfigurationException
     {
         boolean result;
 
         if (StringUtils.isNotEmpty(getInclude())
                 && key.equalsIgnoreCase(getInclude()))
         {
             if (getIncludesAllowed())
             {
                 String[] files;
                 if (!isDelimiterParsingDisabled())
                 {
                     files = StringUtils.split(value, getListDelimiter());
                 }
                 else
                 {
                     files = new String[]{value};
                 }
                 for (int i = 0; i < files.length; i++)
                 {
                     loadIncludeFile(files[i].trim());
                 }
             }
             result = false;
         }
 
         else
         {
             addProperty(key, value);
             result = true;
         }
 
         return result;
     }
 
     /**
      * Tests whether a line is a comment, i.e. whether it starts with a comment
      * character.
      *
      * @param line the line
      * @return a flag if this is a comment line
      * @since 1.3
      */
     static boolean isCommentLine(String line)
     {
         String s = line.trim();
         // blanc lines are also treated as comment lines
         return s.length() < 1 || COMMENT_CHARS.indexOf(s.charAt(0)) >= 0;
     }
 
     /**
      * This class is used to read properties lines. These lines do
      * not terminate with new-line chars but rather when there is no
      * backslash sign a the end of the line.  This is used to
      * concatenate multiple lines for readability.
      */
     public static class PropertiesReader extends LineNumberReader
     {
         /** Stores the comment lines for the currently processed property.*/
         private List commentLines;
 
         /** Stores the name of the last read property.*/
         private String propertyName;
 
         /** Stores the value of the last read property.*/
         private String propertyValue;
 
         /** Stores the list delimiter character.*/
         private char delimiter;
 
         /**
          * Constructor.
          *
          * @param reader A Reader.
          */
         public PropertiesReader(Reader reader)
         {
             this(reader, AbstractConfiguration.getDefaultListDelimiter());
         }
 
         /**
          * Creates a new instance of <code>PropertiesReader</code> and sets
          * the underlaying reader and the list delimiter.
          *
          * @param reader the reader
          * @param listDelimiter the list delimiter character
          * @since 1.3
          */
         public PropertiesReader(Reader reader, char listDelimiter)
         {
             super(reader);
             commentLines = new ArrayList();
             delimiter = listDelimiter;
         }
 
         /**
          * Reads a property line. Returns null if Stream is
          * at EOF. Concatenates lines ending with "\".
          * Skips lines beginning with "#" or "!" and empty lines.
          * The return value is a property definition (<code>&lt;name&gt;</code>
          * = <code>&lt;value&gt;</code>)
          *
          * @return A string containing a property value or null
          *
          * @throws IOException in case of an I/O error
          */
         public String readProperty() throws IOException
         {
             commentLines.clear();
             StringBuffer buffer = new StringBuffer();
 
             while (true)
             {
                 String line = readLine();
                 if (line == null)
                 {
                     // EOF
                     return null;
                 }
 
                 if (isCommentLine(line))
                 {
                     commentLines.add(line);
                     continue;
                 }
 
                 line = line.trim();
 
                 if (checkCombineLines(line))
                 {
                     line = line.substring(0, line.length() - 1);
                     buffer.append(line);
                 }
                 else
                 {
                     buffer.append(line);
                     break;
                 }
             }
             return buffer.toString();
         }
 
         /**
          * Parses the next property from the input stream and stores the found
          * name and value in internal fields. These fields can be obtained using
          * the provided getter methods. The return value indicates whether EOF
          * was reached (<b>false</b>) or whether further properties are
          * available (<b>true</b>).
          *
          * @return a flag if further properties are available
          * @throws IOException if an error occurs
          * @since 1.3
          */
         public boolean nextProperty() throws IOException
         {
             String line = readProperty();
 
             if (line == null)
             {
                 return false; // EOF
             }
 
             // parse the line
             String[] property = parseProperty(line);
             propertyName = StringEscapeUtils.unescapeJava(property[0]);
             propertyValue = unescapeJava(property[1], delimiter);
             return true;
         }
 
         /**
          * Returns the comment lines that have been read for the last property.
          *
          * @return the comment lines for the last property returned by
          * <code>readProperty()</code>
          * @since 1.3
          */
         public List getCommentLines()
         {
             return commentLines;
         }
 
         /**
          * Returns the name of the last read property. This method can be called
          * after <code>{@link #nextProperty()}</code> was invoked and its
          * return value was <b>true</b>.
          *
          * @return the name of the last read property
          * @since 1.3
          */
         public String getPropertyName()
         {
             return propertyName;
         }
 
         /**
          * Returns the value of the last read property. This method can be
          * called after <code>{@link #nextProperty()}</code> was invoked and
          * its return value was <b>true</b>.
          *
          * @return the value of the last read property
          * @since 1.3
          */
         public String getPropertyValue()
         {
             return propertyValue;
         }
 
         /**
          * Checks if the passed in line should be combined with the following.
          * This is true, if the line ends with an odd number of backslashes.
          *
          * @param line the line
          * @return a flag if the lines should be combined
          */
         private static boolean checkCombineLines(String line)
         {
             int bsCount = 0;
             for (int idx = line.length() - 1; idx >= 0 && line.charAt(idx) == '\\'; idx--)
             {
                 bsCount++;
             }
 
             return bsCount % 2 == 1;
         }
 
         /**
          * Parse a property line and return the key and the value in an array.
          *
          * @param line the line to parse
          * @return an array with the property's key and value
          * @since 1.2
          */
         private static String[] parseProperty(String line)
         {
             // sorry for this spaghetti code, please replace it as soon as
             // possible with a regexp when the Java 1.3 requirement is dropped
 
             String[] result = new String[2];
             StringBuffer key = new StringBuffer();
             StringBuffer value = new StringBuffer();
 
             // state of the automaton:
             // 0: key parsing
             // 1: antislash found while parsing the key
             // 2: separator crossing
             // 3: value parsing
             int state = 0;
 
             for (int pos = 0; pos < line.length(); pos++)
             {
                 char c = line.charAt(pos);
 
                 switch (state)
                 {
                     case 0:
                         if (c == '\\')
                         {
                             state = 1;
                         }
                         else if (ArrayUtils.contains(WHITE_SPACE, c))
                         {
                             // switch to the separator crossing state
                             state = 2;
                         }
                         else if (ArrayUtils.contains(SEPARATORS, c))
                         {
                             // switch to the value parsing state
                             state = 3;
                         }
                         else
                         {
                             key.append(c);
                         }
 
                         break;
 
                     case 1:
                         if (ArrayUtils.contains(SEPARATORS, c) || ArrayUtils.contains(WHITE_SPACE, c))
                         {
                             // this is an escaped separator or white space
                             key.append(c);
                         }
                         else
                         {
                             // another escaped character, the '\' is preserved
                             key.append('\\');
                             key.append(c);
                         }
 
                         // return to the key parsing state
                         state = 0;
 
                         break;
 
                     case 2:
                         if (ArrayUtils.contains(WHITE_SPACE, c))
                         {
                             // do nothing, eat all white spaces
                             state = 2;
                         }
                         else if (ArrayUtils.contains(SEPARATORS, c))
                         {
                             // switch to the value parsing state
                             state = 3;
                         }
                         else
                         {
                             // any other character indicates we encoutered the beginning of the value
                             value.append(c);
 
                             // switch to the value parsing state
                             state = 3;
                         }
 
                         break;
 
                     case 3:
                         value.append(c);
                         break;
                 }
             }
 
             result[0] = key.toString().trim();
             result[1] = value.toString().trim();
 
             return result;
         }
     } // class PropertiesReader
 
     /**
      * This class is used to write properties lines.
      */
     public static class PropertiesWriter extends FilterWriter
     {
         /** The delimiter for multi-valued properties.*/
         private char delimiter;
 
         /**
          * Constructor.
          *
          * @param writer a Writer object providing the underlying stream
          * @param delimiter the delimiter character for multi-valued properties
          */
         public PropertiesWriter(Writer writer, char delimiter)
         {
             super(writer);
             this.delimiter = delimiter;
         }
 
         /**
          * Write a property.
          *
          * @param key the key of the property
          * @param value the value of the property
          *
          * @throws IOException if an I/O error occurs
          */
         public void writeProperty(String key, Object value) throws IOException
         {
             writeProperty(key, value, false);
         }
 
         /**
          * Write a property.
          *
          * @param key The key of the property
          * @param values The array of values of the property
          *
          * @throws IOException if an I/O error occurs
          */
         public void writeProperty(String key, List values) throws IOException
         {
             for (int i = 0; i < values.size(); i++)
             {
                 writeProperty(key, values.get(i));
             }
         }
 
         /**
          * Writes the given property and its value. If the value happens to be a
          * list, the <code>forceSingleLine</code> flag is evaluated. If it is
          * set, all values are written on a single line using the list delimiter
          * as separator.
          *
          * @param key the property key
          * @param value the property value
          * @param forceSingleLine the &quot;force single line&quot; flag
          * @throws IOException if an error occurs
          * @since 1.3
          */
         public void writeProperty(String key, Object value,
                 boolean forceSingleLine) throws IOException
         {
             String v;
 
             if (value instanceof List)
             {
                 List values = (List) value;
                 if (forceSingleLine)
                 {
                     v = makeSingleLineValue(values);
                 }
                 else
                 {
                     writeProperty(key, values);
                     return;
                 }
             }
             else
             {
                 v = escapeValue(value);
             }
 
             write(escapeKey(key));
             write(" = ");
             write(v);
 
             writeln(null);
         }
 
         /**
          * Write a comment.
          *
          * @param comment the comment to write
          * @throws IOException if an I/O error occurs
          */
         public void writeComment(String comment) throws IOException
         {
             writeln("# " + comment);
         }
 
         /**
          * Escape the separators in the key.
          *
          * @param key the key
          * @return the escaped key
          * @since 1.2
          */
         private String escapeKey(String key)
         {
             StringBuffer newkey = new StringBuffer();
 
             for (int i = 0; i < key.length(); i++)
             {
                 char c = key.charAt(i);
 
                 if (ArrayUtils.contains(SEPARATORS, c) || ArrayUtils.contains(WHITE_SPACE, c))
                 {
                     // escape the separator
                     newkey.append('\\');
                     newkey.append(c);
                 }
                 else
                 {
                     newkey.append(c);
                 }
             }
 
             return newkey.toString();
         }
 
         /**
          * Escapes the given property value. Delimiter characters in the value
          * will be escaped.
          *
          * @param value the property value
          * @return the escaped property value
          * @since 1.3
          */
         private String escapeValue(Object value)
         {
             String v = StringEscapeUtils.escapeJava(String.valueOf(value));
             return StringUtils.replace(v, String.valueOf(delimiter), "\\"
                     + delimiter);
         }
 
         /**
          * Transforms a list of values into a single line value.
          *
          * @param values the list with the values
          * @return a string with the single line value (can be <b>null</b>)
          * @since 1.3
          */
         private String makeSingleLineValue(List values)
         {
             if (!values.isEmpty())
             {
                 Iterator it = values.iterator();
                 StringBuffer buf = new StringBuffer(escapeValue(it.next()));
                 while (it.hasNext())
                 {
                     buf.append(delimiter);
                     buf.append(escapeValue(it.next()));
                 }
                 return buf.toString();
             }
             else
             {
                 return null;
             }
         }
 
         /**
          * Helper method for writing a line with the platform specific line
          * ending.
          *
          * @param s the content of the line (may be <b>null</b>)
          * @throws IOException if an error occurs
          * @since 1.3
          */
         public void writeln(String s) throws IOException
         {
             if (s != null)
             {
                 write(s);
             }
             write(LINE_SEPARATOR);
         }
 
     } // class PropertiesWriter
 
     /**
      * <p>Unescapes any Java literals found in the <code>String</code> to a
      * <code>Writer</code>.</p> This is a slightly modified version of the
      * StringEscapeUtils.unescapeJava() function in commons-lang that doesn't
      * drop escaped separators (i.e '\,').
      *
      * @param str  the <code>String</code> to unescape, may be null
      * @param delimiter the delimiter for multi-valued properties
      * @return the processed string
      * @throws IllegalArgumentException if the Writer is <code>null</code>
      */
     protected static String unescapeJava(String str, char delimiter)
     {
         if (str == null)
         {
             return null;
         }
         int sz = str.length();
         StringBuffer out = new StringBuffer(sz);
         StringBuffer unicode = new StringBuffer(UNICODE_LEN);
         boolean hadSlash = false;
         boolean inUnicode = false;
         for (int i = 0; i < sz; i++)
         {
             char ch = str.charAt(i);
             if (inUnicode)
             {
                 // if in unicode, then we're reading unicode
                 // values in somehow
                 unicode.append(ch);
                 if (unicode.length() == UNICODE_LEN)
                 {
                     // unicode now contains the four hex digits
                     // which represents our unicode character
                     try
                     {
                         int value = Integer.parseInt(unicode.toString(), HEX_RADIX);
                         out.append((char) value);
                         unicode.setLength(0);
                         inUnicode = false;
                         hadSlash = false;
                     }
                     catch (NumberFormatException nfe)
                     {
                         throw new ConfigurationRuntimeException("Unable to parse unicode value: " + unicode, nfe);
                     }
                 }
                 continue;
             }
 
             if (hadSlash)
             {
                 // handle an escaped value
                 hadSlash = false;
 
                 if (ch == '\\')
                 {
                     out.append('\\');
                 }
                 else if (ch == '\'')
                 {
                     out.append('\'');
                 }
                 else if (ch == '\"')
                 {
                     out.append('"');
                 }
                 else if (ch == 'r')
                 {
                     out.append('\r');
                 }
                 else if (ch == 'f')
                 {
                     out.append('\f');
                 }
                 else if (ch == 't')
                 {
                     out.append('\t');
                 }
                 else if (ch == 'n')
                 {
                     out.append('\n');
                 }
                 else if (ch == 'b')
                 {
                     out.append('\b');
                 }
                 else if (ch == delimiter)
                 {
                     out.append('\\');
                     out.append(delimiter);
                 }
                 else if (ch == 'u')
                 {
                     // uh-oh, we're in unicode country....
                     inUnicode = true;
                 }
                 else
                 {
                     out.append(ch);
                 }
 
                 continue;
             }
             else if (ch == '\\')
             {
                 hadSlash = true;
                 continue;
             }
             out.append(ch);
         }
 
         if (hadSlash)
         {
             // then we're in the weird case of a \ at the end of the
             // string, let's output it anyway.
             out.append('\\');
         }
 
         return out.toString();
     }
 
     /**
      * Helper method for loading an included properties file. This method is
      * called by <code>load()</code> when an <code>include</code> property
      * is encountered. It tries to resolve relative file names based on the
      * current base path. If this fails, a resolution based on the location of
      * this properties file is tried.
      *
      * @param fileName the name of the file to load
      * @throws ConfigurationException if loading fails
      */
     private void loadIncludeFile(String fileName) throws ConfigurationException
     {
         URL url = ConfigurationUtils.locate(getBasePath(), fileName);
         if (url == null)
         {
             URL baseURL = getURL();
             if (baseURL != null)
             {
                 url = ConfigurationUtils.locate(baseURL.toString(), fileName);
             }
         }
 
         if (url == null)
         {
             throw new ConfigurationException("Cannot resolve include file "
                     + fileName);
         }
         load(url);
     }
 }