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## org.apache.commons.configuration
Class PropertiesConfiguration

    java.lang.Object
      org.apache.commons.configuration.event.EventSource
          org.apache.commons.configuration.AbstractConfiguration
              org.apache.commons.configuration.BaseConfiguration
                  org.apache.commons.configuration.AbstractFileConfiguration
                      org.apache.commons.configuration.PropertiesConfiguration

All Implemented Interfaces:
  Cloneable, Configuration, FileConfiguration

Direct Known Subclasses:
  XMLPropertiesConfiguration

public class PropertiesConfiguration
extends AbstractFileConfiguration

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.

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.

The properties file syntax is explained here, basically it follows the syntax of the stream parsed by `Properties.load(java.io.InputStream)` and adds several useful extensions:

- Each property has the syntax `key <separator> value`. The separators accepted are `'='`, `':'` and any white space character. Examples:

        key1 = value1
        key2 : value2
        key3   value3

- The key may use any character, separators must be escaped:

        key\:foo = bar

- value may be separated on different lines if a backslash is placed at the end of the line that continues below.
- value can contain value delimiters and will then be interpreted as a list of tokens. Default value delimiter is the comma ','. So the following property definition

        key = This property, has multiple, values

  will result in a property with three values. You can change the value delimiter using the ``AbstractConfiguration.setListDelimiter(char)`` method. Setting the delimiter to 0 will disable value splitting completely.
- Commas in each token are escaped placing a backslash right before the comma.
- If a key is used more than once, the values are appended like if they were on the same line separated with commas. Note: When the configuration file is written back to disk the associated ``PropertiesConfigurationLayout`` object (see below) will try to preserve as much of the original format as possible, i.e. properties with multiple values defined on a single line will also be written back on a single line, and multiple occurrences of a single key will be written on multiple lines. If the `addProperty()` method was called multiple times for adding multiple values to a property, these properties will per default be written on multiple lines in the output file, too. Some options of the `PropertiesConfigurationLayout` class have influence on that behavior.
- Blank lines and lines starting with character '#' or '!' are skipped.
- 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.

Here is an example of a valid extended properties file:

          # 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

A `PropertiesConfiguration` object is associated with an instance of the ``PropertiesConfigurationLayout`` class, which is responsible for storing the layout of the parsed properties file (i.e. empty lines, comments, and such things). The `getLayout()` method can be used to obtain this layout object. With `setLayout()` a new layout object can be set. This should be done before a properties file was loaded.

Note:Configuration objects of this type can be read concurrently by multiple threads. However if one of these threads modifies the object, synchronization has to be performed manually.

Version:
  $Id: PropertiesConfiguration.java 727168 2008-12-16 21:44:29Z oheger $
Author:
  Stefano Mazzocchi, Jon S. Stevens, Dave Bryson, Geir Magnusson Jr., Leon Messerschmidt, Kent Johnson, Daniel Rall, Ilkka Priha, Jason van Zyl, Martin Poeschl, Henning P. Schmiedehausen, Eric Pugh, Oliver Heger, Emmanuel Bourg
See Also:
  `Properties.load(java.io.InputStream)`

Nested Class Summary
`static class` | `PropertiesConfiguration.PropertiesReader` This class is used to read properties lines.
`static class` | `PropertiesConfiguration.PropertiesWriter` This class is used to write properties lines.

Field Summary

Fields inherited from class org.apache.commons.configuration.AbstractFileConfiguration
`autoSave, basePath, EVENT_RELOAD, fileName, strategy`

Fields inherited from class org.apache.commons.configuration.AbstractConfiguration
`END_TOKEN, EVENT_ADD_PROPERTY, EVENT_CLEAR, EVENT_CLEAR_PROPERTY, EVENT_READ_PROPERTY, EVENT_SET_PROPERTY, START_TOKEN`

Constructor Summary
`PropertiesConfiguration()` Creates an empty PropertyConfiguration object which can be used to synthesize a new Properties file by adding values and then saving().
`PropertiesConfiguration(File file)` Creates and loads the extended properties from the specified file.
`PropertiesConfiguration(String fileName)` Creates and loads the extended properties from the specified file.
`PropertiesConfiguration(URL url)` Creates and loads the extended properties from the specified URL.

Method Summary
`Object` | `clone()` Creates a copy of this object.
`protected PropertiesConfigurationLayout` | `createLayout()` Creates the associated layout object.
`String` | `getEncoding()` Returns the encoding to be used when loading or storing configuration data.
`String` | `getHeader()` Return the comment header.
`static String` | `getInclude()` Gets the property value for including other properties files.
`boolean` | `getIncludesAllowed()` Reports the status of file inclusion.
`PropertiesConfigurationLayout` | `getLayout()` Returns the associated layout object.
`void` | `load(Reader in)` Load the properties from the given reader.
`void` | `save(Writer writer)` Save the configuration to the specified stream.
`void` | `setBasePath(String basePath)` Extend the setBasePath method to turn includes on and off based on the existence of a base path.
`void` | `setHeader(String header)` Set the comment header.
`static void` | `setInclude(String inc)` Sets the property value for including other properties files.
`protected void` | `setIncludesAllowed(boolean includesAllowed)` Controls whether additional files can be loaded by the include = statement or not.
`void` | `setLayout(PropertiesConfigurationLayout layout)` Sets the associated layout object.
`protected static String` | `unescapeJava(String str, char delimiter)` Unescapes any Java literals found in the `String` to a `Writer`.

Methods inherited from class org.apache.commons.configuration.AbstractFileConfiguration
`addProperty, clearProperty, containsKey, enterNoReload, exitNoReload, fireEvent, getBasePath, getFile, getFileName, getKeys, getPath, getProperty, getReloadingStrategy, getURL, isAutoSave, isEmpty, load, load, load, load, load, load, possiblySave, reload, save, save, save, save, save, save, setAutoSave, setEncoding, setFile, setFileName, setPath, setProperty, setReloadingStrategy, setURL`

Methods inherited from class org.apache.commons.configuration.BaseConfiguration
`addPropertyDirect, clear, clearPropertyDirect`

Methods inherited from class org.apache.commons.configuration.AbstractConfiguration
`addErrorLogListener, append, copy, createInterpolator, getBigDecimal, getBigDecimal, getBigInteger, getBigInteger, getBoolean, getBoolean, getBoolean, getByte, getByte, getByte, getDefaultListDelimiter, getDelimiter, getDouble, getDouble, getDouble, getFloat, getFloat, getFloat, getInt, getInt, getInteger, getInterpolator, getKeys, getList, getList, getListDelimiter, getLogger, getLong, getLong, getLong, getProperties, getProperties, getShort, getShort, getShort, getString, getString, getStringArray, getSubstitutor, interpolate, interpolate, interpolatedConfiguration, interpolateHelper, isDelimiterParsingDisabled, isThrowExceptionOnMissing, resolveContainerStore, setDefaultListDelimiter, setDelimiter, setDelimiterParsingDisabled, setListDelimiter, setLogger, setThrowExceptionOnMissing, subset`

Methods inherited from class org.apache.commons.configuration.event.EventSource
`addConfigurationListener, addErrorListener, clearConfigurationListeners, clearErrorListeners, createErrorEvent, createEvent, fireError, getConfigurationListeners, getErrorListeners, isDetailEvents, removeConfigurationListener, removeErrorListener, setDetailEvents`

Methods inherited from class java.lang.Object
`equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Methods inherited from interface org.apache.commons.configuration.Configuration
`clear, getBigDecimal, getBigDecimal, getBigInteger, getBigInteger, getBoolean, getBoolean, getBoolean, getByte, getByte, getByte, getDouble, getDouble, getDouble, getFloat, getFloat, getFloat, getInt, getInt, getInteger, getKeys, getList, getList, getLong, getLong, getLong, getProperties, getShort, getShort, getShort, getString, getString, getStringArray, subset`

Constructor Detail

### PropertiesConfiguration

    public PropertiesConfiguration()

  Creates an empty PropertyConfiguration object which can be used to synthesize a new Properties file by adding values and then saving().

### PropertiesConfiguration

    public PropertiesConfiguration(String fileName)
                            throws ConfigurationException

  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.

Parameters:
  `fileName` - The name of the properties file to load.
Throws:
  `ConfigurationException` - Error while loading the properties file

### PropertiesConfiguration

    public PropertiesConfiguration(File file)
                            throws ConfigurationException

  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. If the file does not exist, an empty configuration will be created. Later the `save()` method can be called to save the properties to the specified file.

Parameters:
  `file` - The properties file to load.
Throws:
  `ConfigurationException` - Error while loading the properties file

### PropertiesConfiguration

    public PropertiesConfiguration(URL url)
                            throws ConfigurationException

  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.

Parameters:
  `url` - The location of the properties file to load.
Throws:
  `ConfigurationException` - Error while loading the properties file

Method Detail

### getInclude

    public static String getInclude()

  Gets the property value for including other properties files. By default it is "include".

  Returns:
    A String.

### setInclude

    public static void setInclude(String inc)

  Sets the property value for including other properties files. By default it is "include".

  Parameters:
    `inc` - A String.

### setIncludesAllowed

    protected void setIncludesAllowed(boolean includesAllowed)

  Controls whether additional files can be loaded by the include = statement or not. Base rule is, that objects created by the empty C'tor can not have included files.

  Parameters:
    `includesAllowed` - includesAllowed True if Includes are allowed.

### getIncludesAllowed

    public boolean getIncludesAllowed()

  Reports the status of file inclusion.

  Returns:
    True if include files are loaded.

### getHeader

    public String getHeader()

  Return the comment header.

  Returns:
    the comment header
  Since:
    1.1

### setHeader

    public void setHeader(String header)

  Set the comment header.

  Parameters:
    `header` - the header to use
  Since:
    1.1

### getEncoding

    public String getEncoding()

  Returns the encoding to be used when loading or storing configuration data. This implementation ensures that the default encoding will be used if none has been set explicitly.

  Specified by:
    `getEncoding` in interface `FileConfiguration`
  Overrides:
    `getEncoding` in class `AbstractFileConfiguration`
  Returns:
    the encoding

### getLayout

    public PropertiesConfigurationLayout getLayout()

  Returns the associated layout object.

  Returns:
    the associated layout object
  Since:
    1.3

### setLayout

    public void setLayout(PropertiesConfigurationLayout layout)

  Sets the associated layout object.

  Parameters:
    `layout` - the new layout object; can be null, then a new layout object will be created
  Since:
    1.3

### createLayout

    protected PropertiesConfigurationLayout createLayout()

  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.

  Returns:
    the layout object to use
  Since:
    1.3

### load

    public void load(Reader in)
              throws ConfigurationException

  Load the properties from the given reader. Note that the `clear()` method is not called, so the properties contained in the loaded file will be added to the actual set of properties.

  Parameters:
    `in` - An InputStream.
  Throws:
    `ConfigurationException` - if an error occurs

### save

    public void save(Writer writer)
              throws ConfigurationException

  Save the configuration to the specified stream.

  Parameters:
    `writer` - the output stream used to save the configuration
  Throws:
    `ConfigurationException` - if an error occurs

### setBasePath

    public void setBasePath(String basePath)

  Extend the setBasePath method to turn includes on and off based on the existence of a base path.

  Specified by:
    `setBasePath` in interface `FileConfiguration`
  Overrides:
    `setBasePath` in class `AbstractFileConfiguration`
  Parameters:
    `basePath` - The new basePath to set.

### clone

    public Object clone()

  Creates a copy of this object.

  Overrides:
    `clone` in class `AbstractFileConfiguration`
  Returns:
    the copy

### unescapeJava

    protected static String unescapeJava(String str,
                                         char delimiter)

  Unescapes any Java literals found in the `String` to a `Writer`.

  This is a slightly modified version of the StringEscapeUtils.unescapeJava() function in commons-lang that doesn't drop escaped separators (i.e '\,').

  Parameters:
    `str` - the `String` to unescape, may be null
    `delimiter` - the delimiter for multi-valued properties
  Returns:
    the processed string
  Throws:
    `IllegalArgumentException` - if the Writer is `null`

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