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.
• 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.

Version:

$Id: PropertiesConfiguration.java 439648 2006-09-02 20:42:10Z 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

(package private) static String

COMMENT_CHARS Constant for the supported comment characters.

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_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	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.
(package private) static boolean	isCommentLine(String line) Tests whether a line is a comment, i.e. whether it starts with a comment character.
void	load(Reader in) Load the properties from the given reader.
(package private) boolean	propertyLoaded(String key, String value) This method is invoked by the associated PropertiesConfigurationLayout object for each property definition detected in the parsed properties file.
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, getEncoding, 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

getBigDecimal, getBigDecimal, getBigInteger, getBigInteger, getBoolean, getBoolean, getBoolean, getByte, getByte, getByte, getDefaultListDelimiter, getDelimiter, getDouble, getDouble, getDouble, getFloat, getFloat, getFloat, getInt, getInt, getInteger, getKeys, getList, getList, getListDelimiter, getLong, getLong, getLong, getProperties, getProperties, getShort, getShort, getShort, getString, getString, getStringArray, interpolate, interpolate, interpolateHelper, isDelimiterParsingDisabled, isThrowExceptionOnMissing, resolveContainerStore, setDefaultListDelimiter, setDelimiter, setDelimiterParsingDisabled, setListDelimiter, setThrowExceptionOnMissing, subset

Methods inherited from class org.apache.commons.configuration.event.EventSource

addConfigurationListener, clearConfigurationListeners, createEvent, getConfigurationListeners, isDetailEvents, removeConfigurationListener, 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

Field Detail

COMMENT_CHARS

static final String COMMENT_CHARS

Constant for the supported comment characters.

See Also:

Constant Field Values

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.

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

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

propertyLoaded

boolean propertyLoaded(String key,
                       String value)
                 throws ConfigurationException

This method is invoked by the associated PropertiesConfigurationLayout 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 include 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 false, the layout object will ignore this property.

Parameters:

key - the property key

value - the property value

Returns:

a flag whether this is a normal property

Throws:

ConfigurationException - if an error occurs

Since:

1.3

isCommentLine

static boolean isCommentLine(String line)

Tests whether a line is a comment, i.e. whether it starts with a comment character.

Parameters:

line - the line

Returns:

a flag if this is a comment line

Since:

1.3

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