Package org.springframework.core

Class Constants

  • public class Constants
extends Object
    This class can be used to parse other classes containing constant definitions in public static final members. The asXXXX methods of this class allow these constant values to be accessed via their string names.

    Consider class Foo containing public final static int CONSTANT1 = 66; An instance of this class wrapping Foo.class will return the constant value of 66 from its asNumber method given the argument "CONSTANT1".

    This class is ideal for use in PropertyEditors, enabling them to recognize the same names as the constants themselves, and freeing them from maintaining their own mapping.

    Since:
    16.03.2003
    Author:
    Rod Johnson, Juergen Hoeller

    • Constructor Detail

      • Constants

        public Constants​(Class<?> clazz)
        Create a new Constants converter class wrapping the given class.

        All public static final variables will be exposed, whatever their type.

        Parameters:
        clazz - the class to analyze
        Throws:
        IllegalArgumentException - if the supplied clazz is null

    • Method Detail

      • getSize

        public final int getSize()
        Return the number of constants exposed.

      • getFieldCache

        protected final Map<String,​Object> getFieldCache()
        Exposes the field cache to subclasses: a Map from String field name to object value.

      • asObject

        public Object asObject​(String code)
                throws ConstantException
        Parse the given String (upper or lower case accepted) and return the appropriate value if it's the name of a constant field in the class that we're analysing.
        Parameters:
        code - the name of the field (never null)
        Returns:
        the Object value
        Throws:
        ConstantException - if there's no such field

      • getNames

        public Set<String> getNames​(String namePrefix)
        Return all names of the given group of constants.

        Note that this method assumes that constants are named in accordance with the standard Java convention for constant values (i.e. all uppercase). The supplied namePrefix will be uppercased (in a locale-insensitive fashion) prior to the main logic of this method kicking in.

        Parameters:
        namePrefix - prefix of the constant names to search (may be null)
        Returns:
        the set of constant names

      • getNamesForSuffix

        public Set<String> getNamesForSuffix​(String nameSuffix)
        Return all names of the given group of constants.

        Note that this method assumes that constants are named in accordance with the standard Java convention for constant values (i.e. all uppercase). The supplied nameSuffix will be uppercased (in a locale-insensitive fashion) prior to the main logic of this method kicking in.

        Parameters:
        nameSuffix - suffix of the constant names to search (may be null)
        Returns:
        the set of constant names

      • getValues

        public Set<Object> getValues​(String namePrefix)
        Return all values of the given group of constants.

        Note that this method assumes that constants are named in accordance with the standard Java convention for constant values (i.e. all uppercase). The supplied namePrefix will be uppercased (in a locale-insensitive fashion) prior to the main logic of this method kicking in.

        Parameters:
        namePrefix - prefix of the constant names to search (may be null)
        Returns:
        the set of values

      • getValuesForSuffix

        public Set<Object> getValuesForSuffix​(String nameSuffix)
        Return all values of the given group of constants.

        Note that this method assumes that constants are named in accordance with the standard Java convention for constant values (i.e. all uppercase). The supplied nameSuffix will be uppercased (in a locale-insensitive fashion) prior to the main logic of this method kicking in.

        Parameters:
        nameSuffix - suffix of the constant names to search (may be null)
        Returns:
        the set of values

      • toCode

        public String toCode​(Object value,
                     String namePrefix)
              throws ConstantException
        Look up the given value within the given group of constants.

        Will return the first match.

        Parameters:
        value - constant value to look up
        namePrefix - prefix of the constant names to search (may be null)
        Returns:
        the name of the constant field
        Throws:
        ConstantException - if the value wasn't found

      • toCodeForSuffix

        public String toCodeForSuffix​(Object value,
                              String nameSuffix)
                       throws ConstantException
        Look up the given value within the given group of constants.

        Will return the first match.

        Parameters:
        value - constant value to look up
        nameSuffix - suffix of the constant names to search (may be null)
        Returns:
        the name of the constant field
        Throws:
        ConstantException - if the value wasn't found

      • propertyToConstantNamePrefix

        public String propertyToConstantNamePrefix​(String propertyName)
        Convert the given bean property name to a constant name prefix.

        Uses a common naming idiom: turning all lower case characters to upper case, and prepending upper case characters with an underscore.

        Example: "imageSize" -> "IMAGE_SIZE"
        Example: "imagesize" -> "IMAGESIZE".
        Example: "ImageSize" -> "_IMAGE_SIZE".
        Example: "IMAGESIZE" -> "_I_M_A_G_E_S_I_Z_E"

        Parameters:
        propertyName - the name of the bean property
        Returns:
        the corresponding constant name prefix
        See Also:
        getValuesForProperty(java.lang.String), toCodeForProperty(java.lang.Object, java.lang.String)