Package org.apache.commons.configuration2

Class PropertiesConfigurationLayout

java.lang.Object
org.apache.commons.configuration2.PropertiesConfigurationLayout
All Implemented Interfaces:
EventListener<ConfigurationEvent>
public class PropertiesConfigurationLayout extends Object implements EventListener<ConfigurationEvent>

A helper class used by PropertiesConfiguration to keep the layout of a properties file.

Instances of this class are associated with a PropertiesConfiguration object. They are responsible for analyzing properties files and for extracting as much information about the file layout (e.g. empty lines, comments) as possible. When the properties file is written back again it should be close to the original.

The PropertiesConfigurationLayout object associated with a PropertiesConfiguration object can be obtained using the getLayout() method of the configuration. Then the methods provided by this class can be used to alter the properties file's layout.

Implementation note: This is a very simple implementation, which is far away from being perfect, i.e. the original layout of a properties file won't be reproduced in all cases. One limitation is that comments for multi-valued property keys are concatenated. Maybe this implementation can later be improved.

To get an impression how this class works consider the following properties file: 

 # A demo configuration file
 # for Demo App 1.42

 # Application name
 AppName=Demo App

 # Application vendor
 AppVendor=DemoSoft


 # GUI properties
 # Window Color
 windowColors=0xFFFFFF,0x000000

 # Include some setting
 include=settings.properties
 # Another vendor
 AppVendor=TestSoft

For this example the following points are relevant:

  • The first two lines are set as header comment. The header comment is determined by the last blank line before the first property definition.
  • For the property AppName one comment line and one leading blank line is stored.
  • For the property windowColors two comment lines and two leading blank lines are stored.
  • Include files is something this class cannot deal with well. When saving the properties configuration back, the included properties are simply contained in the original file. The comment before the include property is skipped.
  • For all properties except for AppVendor the "single line" flag is set. This is relevant only for windowColors, which has multiple values defined in one line using the separator character.
  • The AppVendor property appears twice. The comment lines are concatenated, so that layout.getComment("AppVendor"); will result in Application vendor&lt;CR&gt;Another vendor, with &lt;CR&gt; meaning the line separator. In addition the "single line" flag is set to false for this property. When the file is saved, two property definitions will be written (in series).
Since:
1.3

  • Constructor Details

  • Method Details

    • getCanonicalComment

      public String getCanonicalComment(String key, boolean commentChar)
      Gets the comment for the specified property key in a canonical form. "Canonical" means that either all lines start with a comment character or none. If the commentChar parameter is false, all comment characters are removed, so that the result is only the plain text of the comment. Otherwise it is ensured that each line of the comment starts with a comment character. Also, line breaks in the comment are normalized to the line separator "\n".
      Parameters:
      key - the key of the property
      commentChar - determines whether all lines should start with comment characters or not
      Returns:
      the canonical comment for this key (can be null)

    • getComment

      public String getComment(String key)
      Gets the comment for the specified property key. The comment is returned as it was set (either manually by calling setComment() or when it was loaded from a properties file). No modifications are performed.
      Parameters:
      key - the key of the property
      Returns:
      the comment for this key (can be null)

    • setComment

      public void setComment(String key, String comment)
      Sets the comment for the specified property key. The comment (or its single lines if it is a multi-line comment) can start with a comment character. If this is the case, it will be written without changes. Otherwise a default comment character is added automatically.
      Parameters:
      key - the key of the property
      comment - the comment for this key (can be null, then the comment will be removed)

    • getBlancLinesBefore

      @Deprecated public int getBlancLinesBefore(String key)
      Deprecated.
      Use getBlankLinesBefore(String).
      Gets the number of blank lines before this property key. If this key does not exist, 0 will be returned.
      Parameters:
      key - the property key
      Returns:
      the number of blank lines before the property definition for this key

    • getBlankLinesBefore

      public int getBlankLinesBefore(String key)
      Gets the number of blank lines before this property key. If this key does not exist, 0 will be returned.
      Parameters:
      key - the property key
      Returns:
      the number of blank lines before the property definition for this key

    • setBlancLinesBefore

      @Deprecated public void setBlancLinesBefore(String key, int number)
      Deprecated.
      use setBlankLinesBefore(String, int).
      Sets the number of blank lines before the given property key. This can be used for a logical grouping of properties.
      Parameters:
      key - the property key
      number - the number of blank lines to add before this property definition

    • setBlankLinesBefore

      public void setBlankLinesBefore(String key, int number)
      Sets the number of blank lines before the given property key. This can be used for a logical grouping of properties.
      Parameters:
      key - the property key
      number - the number of blank lines to add before this property definition
      Since:
      2.8.0

    • getCanonicalHeaderComment

      public String getCanonicalHeaderComment(boolean commentChar)
      Gets the header comment of the represented properties file in a canonical form. With the commentChar parameter it can be specified whether comment characters should be stripped or be always present.
      Parameters:
      commentChar - determines the presence of comment characters
      Returns:
      the header comment (can be null)

    • getHeaderComment

      public String getHeaderComment()
      Gets the header comment of the represented properties file. This method returns the header comment exactly as it was set using setHeaderComment() or extracted from the loaded properties file.
      Returns:
      the header comment (can be null)

    • setHeaderComment

      public void setHeaderComment(String comment)
      Sets the header comment for the represented properties file. This comment will be output on top of the file.
      Parameters:
      comment - the comment

    • getCanonicalFooterCooment

      public String getCanonicalFooterCooment(boolean commentChar)
      Gets the footer comment of the represented properties file in a canonical form. This method works like getCanonicalHeaderComment(), but reads the footer comment.
      Parameters:
      commentChar - determines the presence of comment characters
      Returns:
      the footer comment (can be null)
      Since:
      2.0
      See Also:

    • getFooterComment

      public String getFooterComment()
      Gets the footer comment of the represented properties file. This method returns the footer comment exactly as it was set using setFooterComment() or extracted from the loaded properties file.
      Returns:
      the footer comment (can be null)
      Since:
      2.0

    • setFooterComment

      public void setFooterComment(String footerComment)
      Sets the footer comment for the represented properties file. This comment will be output at the bottom of the file.
      Parameters:
      footerComment - the footer comment
      Since:
      2.0

    • isSingleLine

      public boolean isSingleLine(String key)
      Returns a flag whether the specified property is defined on a single line. This is meaningful only if this property has multiple values.
      Parameters:
      key - the property key
      Returns:
      a flag if this property is defined on a single line

    • setSingleLine

      public void setSingleLine(String key, boolean f)
      Sets the "single line flag" for the specified property key. This flag is evaluated if the property has multiple values (i.e. if it is a list property). In this case, if the flag is set, all values will be written in a single property definition using the list delimiter as separator. Otherwise multiple lines will be written for this property, each line containing one property value.
      Parameters:
      key - the property key
      f - the single line flag

    • isForceSingleLine

      public boolean isForceSingleLine()
      Returns the "force single line" flag.
      Returns:
      the force single line flag
      See Also:

    • setForceSingleLine

      public void setForceSingleLine(boolean f)
      Sets the "force single line" flag. If this flag is set, all properties with multiple values are written on single lines. This mode provides more compatibility with Properties, which cannot deal with multiple definitions of a single property. This mode has no effect if the list delimiter parsing is disabled.
      Parameters:
      f - the force single line flag

    • getSeparator

      public String getSeparator(String key)
      Gets the separator for the property with the given key.
      Parameters:
      key - the property key
      Returns:
      the property separator for this property
      Since:
      1.7

    • setSeparator

      public void setSeparator(String key, String sep)
      Sets the separator to be used for the property with the given key. The separator is the string between the property key and its value. For new properties " = " is used. When a properties file is read, the layout tries to determine the separator for each property. With this method the separator can be changed. To be compatible with the properties format only the characters = and : (with or without whitespace) should be used, but this method does not enforce this - it accepts arbitrary strings. If the key refers to a property with multiple values that are written on multiple lines, this separator will be used on all lines.
      Parameters:
      key - the key for the property
      sep - the separator to be used for this property
      Since:
      1.7

    • getGlobalSeparator

      public String getGlobalSeparator()
      Gets the global separator.
      Returns:
      the global properties separator
      Since:
      1.7

    • setGlobalSeparator

      public void setGlobalSeparator(String globalSeparator)
      Sets the global separator for properties. With this method a separator can be set that will be used for all properties when writing the configuration. This is an easy way of determining the properties separator globally. To be compatible with the properties format only the characters = and : (with or without whitespace) should be used, but this method does not enforce this - it accepts arbitrary strings. If the global separator is set to null, property separators are not changed. This is the default behavior as it produces results that are closer to the original properties file.
      Parameters:
      globalSeparator - the separator to be used for all properties
      Since:
      1.7

    • getLineSeparator

      public String getLineSeparator()
      Gets the line separator.
      Returns:
      the line separator
      Since:
      1.7

    • setLineSeparator

      public void setLineSeparator(String lineSeparator)
      Sets the line separator. When writing the properties configuration, all lines are terminated with this separator. If no separator was set, the platform-specific default line separator is used.
      Parameters:
      lineSeparator - the line separator
      Since:
      1.7

    • getKeys

      public Set<String> getKeys()
      Gets a set with all property keys managed by this object.
      Returns:
      a set with all contained property keys

    • load

      public void load(PropertiesConfiguration config, Reader reader) throws ConfigurationException
      Reads a properties file and stores its internal structure. The found properties will be added to the specified configuration object.
      Parameters:
      config - the associated configuration object
      reader - the reader to the properties file
      Throws:
      ConfigurationException - if an error occurs

    • save

      public void save(PropertiesConfiguration config, Writer writer) throws ConfigurationException
      Writes the properties file to the given writer, preserving as much of its structure as possible.
      Parameters:
      config - the associated configuration object
      writer - the writer
      Throws:
      ConfigurationException - if an error occurs

    • onEvent

      public void onEvent(ConfigurationEvent event)
      The event listener callback. Here event notifications of the configuration object are processed to update the layout object properly.
      Specified by:
      onEvent in interface EventListener<ConfigurationEvent>
      Parameters:
      event - the event object