Package org.apache.commons.configuration

Class MapConfiguration

  • All Implemented Interfaces:
    java.lang.Cloneable, Configuration
    Direct Known Subclasses:
    EnvironmentConfiguration, SystemConfiguration
    public class MapConfiguration
extends AbstractConfiguration
implements java.lang.Cloneable

    A Map based Configuration.

    This implementation of the Configuration interface is initialized with a java.util.Map. The methods of the Configuration interface are implemented on top of the content of this map. The following storage scheme is used:

    Property keys are directly mapped to map keys, i.e. the getProperty() method directly performs a get() on the map. Analogously, setProperty() or addProperty() operations write new data into the map. If a value is added to an existing property, a java.util.List is created, which stores the values of this property.

    An important use case of this class is to treat a map as a Configuration allowing access to its data through the richer interface. This can be a bit problematic in some cases because the map may contain values that need not adhere to the default storage scheme used by typical configuration implementations, e.g. regarding lists. In such cases care must be taken when manipulating the data through the Configuration interface, e.g. by calling addProperty(); results may be different than expected.

    An important point is the handling of list delimiters: If delimiter parsing is enabled (which it is per default), getProperty() checks whether the value of a property is a string and whether it contains the list delimiter character. If this is the case, the value is split at the delimiter resulting in a list. This split operation typically also involves trimming the single values as the list delimiter character may be surrounded by whitespace. Trimming can be disabled with the setTrimmingDisabled(boolean) method. The whole list splitting behavior can be disabled using the AbstractConfiguration.setDelimiterParsingDisabled(boolean) method.

    Notice that list splitting is only performed for single string values. If a property has multiple values, the single values are not split even if they contain the list delimiter character.

    As the underlying Map is directly used as store of the property values, the thread-safety of this Configuration implementation depends on the map passed to the constructor.

    Notes about type safety: For properties with multiple values this implementation creates lists of type Object and stores them. If a property is assigned another value, the value is added to the list. This can cause problems if the map passed to the constructor already contains lists of other types. This should be avoided, otherwise it cannot be guaranteed that the application might throw ClassCastException exceptions later.

    Since:
    1.1
    Version:
    $Id: MapConfiguration.java 1534429 2013-10-22 00:45:36Z henning $
    Author:
    Emmanuel Bourg

    • Field Detail

      • map

        protected java.util.Map<java.lang.String,​java.lang.Object> map
        The Map decorated by this configuration.

    • Constructor Detail

      • MapConfiguration

        public MapConfiguration​(java.util.Map<java.lang.String,​?> map)
        Create a Configuration decorator around the specified Map. The map is used to store the configuration properties, any change will also affect the Map.
        Parameters:
        map - the map

      • MapConfiguration

        public MapConfiguration​(java.util.Properties props)
        Creates a new instance of MapConfiguration and initializes its content from the specified Properties object. The resulting configuration is not connected to the Properties object, but all keys which are strings are copied (keys of other types are ignored).
        Parameters:
        props - the Properties object defining the content of this configuration
        Throws:
        java.lang.NullPointerException - if the Properties object is null
        Since:
        1.8

    • Method Detail

      • getMap

        public java.util.Map<java.lang.String,​java.lang.Object> getMap()
        Return the Map decorated by this configuration.
        Returns:
        the map this configuration is based onto

      • isTrimmingDisabled

        public boolean isTrimmingDisabled()
        Returns the flag whether trimming of property values is disabled.
        Returns:
        true if trimming of property values is disabled; false otherwise
        Since:
        1.7

      • setTrimmingDisabled

        public void setTrimmingDisabled​(boolean trimmingDisabled)
        Sets a flag whether trimming of property values is disabled. This flag is only evaluated if list splitting is enabled. Refer to the header comment for more information about list splitting and trimming.
        Parameters:
        trimmingDisabled - a flag whether trimming of property values should be disabled
        Since:
        1.7

      • getProperty

        public java.lang.Object getProperty​(java.lang.String key)
        Description copied from interface: Configuration
        Gets a property from the configuration. This is the most basic get method for retrieving values of properties. In a typical implementation of the Configuration interface the other get methods (that return specific data types) will internally make use of this method. On this level variable substitution is not yet performed. The returned object is an internal representation of the property value for the passed in key. It is owned by the Configuration object. So a caller should not modify this object. It cannot be guaranteed that this object will stay constant over time (i.e. further update operations on the configuration may change its internal state).
        Specified by:
        getProperty in interface Configuration
        Parameters:
        key - property to retrieve
        Returns:
        the value to which this configuration maps the specified key, or null if the configuration contains no mapping for this key.

      • addPropertyDirect

        protected void addPropertyDirect​(java.lang.String key,
                                 java.lang.Object value)
        Description copied from class: AbstractConfiguration
        Adds a key/value pair to the Configuration. Override this method to provide write access to underlying Configuration store.
        Specified by:
        addPropertyDirect in class AbstractConfiguration
        Parameters:
        key - key to use for mapping
        value - object to store

      • isEmpty

        public boolean isEmpty()
        Description copied from interface: Configuration
        Check if the configuration is empty.
        Specified by:
        isEmpty in interface Configuration
        Returns:
        true if the configuration contains no property, false otherwise.

      • containsKey

        public boolean containsKey​(java.lang.String key)
        Description copied from interface: Configuration
        Check if the configuration contains the specified key.
        Specified by:
        containsKey in interface Configuration
        Parameters:
        key - the key whose presence in this configuration is to be tested
        Returns:
        true if the configuration contains a value for this key, false otherwise

      • clearPropertyDirect

        protected void clearPropertyDirect​(java.lang.String key)
        Description copied from class: AbstractConfiguration
        Removes the specified property from this configuration. This method is called by clearProperty() after it has done some preparations. It should be overridden in sub classes. This base implementation is just left empty.
        Overrides:
        clearPropertyDirect in class AbstractConfiguration
        Parameters:
        key - the key to be removed

      • getKeys

        public java.util.Iterator<java.lang.String> getKeys()
        Description copied from interface: Configuration
        Get the list of the keys contained in the configuration. The returned iterator can be used to obtain all defined keys. Note that the exact behavior of the iterator's remove() method is specific to a concrete implementation. It may remove the corresponding property from the configuration, but this is not guaranteed. In any case it is no replacement for calling Configuration.clearProperty(String) for this property. So it is highly recommended to avoid using the iterator's remove() method.
        Specified by:
        getKeys in interface Configuration
        Returns:
        An Iterator.

      • clone

        public java.lang.Object clone()
        Returns a copy of this object. The returned configuration will contain the same properties as the original. Event listeners are not cloned.
        Overrides:
        clone in class EventSource
        Returns:
        the copy
        Since:
        1.3