Spring Framework

org.springframework.core
Class Constants

java.lang.Object
  extended by org.springframework.core.Constants

public class Constants
extends java.lang.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 Summary
Constants(java.lang.Class<?> clazz)
          Create a new Constants converter class wrapping the given class.
 
Method Summary
 java.lang.Number asNumber(java.lang.String code)
          Return a constant value cast to a Number.
 java.lang.Object asObject(java.lang.String code)
          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.
 java.lang.String asString(java.lang.String code)
          Return a constant value as a String.
 java.lang.String getClassName()
          Return the name of the analyzed class.
protected  java.util.Map<java.lang.String,java.lang.Object> getFieldCache()
          Exposes the field cache to subclasses: a Map from String field name to object value.
 java.util.Set<java.lang.String> getNames(java.lang.String namePrefix)
          Return all names of the given group of constants.
 java.util.Set<java.lang.String> getNamesForProperty(java.lang.String propertyName)
          Return all names of the group of constants for the given bean property name.
 java.util.Set<java.lang.String> getNamesForSuffix(java.lang.String nameSuffix)
          Return all names of the given group of constants.
 int getSize()
          Return the number of constants exposed.
 java.util.Set<java.lang.Object> getValues(java.lang.String namePrefix)
          Return all values of the given group of constants.
 java.util.Set<java.lang.Object> getValuesForProperty(java.lang.String propertyName)
          Return all values of the group of constants for the given bean property name.
 java.util.Set<java.lang.Object> getValuesForSuffix(java.lang.String nameSuffix)
          Return all values of the given group of constants.
 java.lang.String propertyToConstantNamePrefix(java.lang.String propertyName)
          Convert the given bean property name to a constant name prefix.
 java.lang.String toCode(java.lang.Object value, java.lang.String namePrefix)
          Look up the given value within the given group of constants.
 java.lang.String toCodeForProperty(java.lang.Object value, java.lang.String propertyName)
          Look up the given value within the group of constants for the given bean property name.
 java.lang.String toCodeForSuffix(java.lang.Object value, java.lang.String nameSuffix)
          Look up the given value within the given group of constants.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Constants

public Constants(java.lang.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:
java.lang.IllegalArgumentException - if the supplied clazz is null
Method Detail

getClassName

public final java.lang.String getClassName()
Return the name of the analyzed class.


getSize

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


getFieldCache

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


asNumber

public java.lang.Number asNumber(java.lang.String code)
                          throws ConstantException
Return a constant value cast to a Number.

Parameters:
code - the name of the field (never null)
Returns:
the Number value
Throws:
ConstantException - if the field name wasn't found or if the type wasn't compatible with Number
See Also:
asObject(java.lang.String)

asString

public java.lang.String asString(java.lang.String code)
                          throws ConstantException
Return a constant value as a String.

Parameters:
code - the name of the field (never null)
Returns:
the String value Works even if it's not a string (invokes toString()).
Throws:
ConstantException - if the field name wasn't found
See Also:
asObject(java.lang.String)

asObject

public java.lang.Object asObject(java.lang.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 java.util.Set<java.lang.String> getNames(java.lang.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

getNamesForProperty

public java.util.Set<java.lang.String> getNamesForProperty(java.lang.String propertyName)
Return all names of the group of constants for the given bean property name.

Parameters:
propertyName - the name of the bean property
Returns:
the set of values
See Also:
propertyToConstantNamePrefix(java.lang.String)

getNamesForSuffix

public java.util.Set<java.lang.String> getNamesForSuffix(java.lang.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 java.util.Set<java.lang.Object> getValues(java.lang.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

getValuesForProperty

public java.util.Set<java.lang.Object> getValuesForProperty(java.lang.String propertyName)
Return all values of the group of constants for the given bean property name.

Parameters:
propertyName - the name of the bean property
Returns:
the set of values
See Also:
propertyToConstantNamePrefix(java.lang.String)

getValuesForSuffix

public java.util.Set<java.lang.Object> getValuesForSuffix(java.lang.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 java.lang.String toCode(java.lang.Object value,
                               java.lang.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

toCodeForProperty

public java.lang.String toCodeForProperty(java.lang.Object value,
                                          java.lang.String propertyName)
                                   throws ConstantException
Look up the given value within the group of constants for the given bean property name. Will return the first match.

Parameters:
value - constant value to look up
propertyName - the name of the bean property
Returns:
the name of the constant field
Throws:
ConstantException - if the value wasn't found
See Also:
propertyToConstantNamePrefix(java.lang.String)

toCodeForSuffix

public java.lang.String toCodeForSuffix(java.lang.Object value,
                                        java.lang.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 java.lang.String propertyToConstantNamePrefix(java.lang.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)

Spring Framework