ariba.util.fieldvalue
Class FieldValue

java.lang.Object
  ariba.util.core.ClassExtension
      ariba.util.fieldvalue.FieldValue

All Implemented Interfaces:

java.lang.Cloneable

Direct Known Subclasses:

FieldValue_Object

public abstract class FieldValue
extends ClassExtension

The FieldValue class defines a ClassExtension for JavaBean-like property access on target objects. Static methods getFieldValue(Object, String) and setFieldValue(Object, String, Object) are provided for convenience. Higher performance access can be achieved by caching FieldPath instances for particular key paths. Not only does that avoid per-access accessor lookup, but the field path caches FieldValueSetter and FieldValueGetter instances from its most recent lookup and can reuse them if the next access targets the same class.

The default implementation of FieldValue is FieldValue_Object -- it resolves property access using reflection to get/set using accessor methods or direct field access. (note that, unlike JavaBeans, FieldValue_Object will resolve a get on key "foo" by checking for foo(), getFoo, and the fields named foo and _foo).

Other specialized implementation of FieldValue exist for Maps, XML Nodes, etc.

Field Summary

static int	Getter
static int	Setter

Fields inherited from class ariba.util.core.ClassExtension

forClass

Constructor Summary

FieldValue()

Method Summary

abstract FieldValueAccessor	createAccessor(java.lang.Object target, java.lang.String fieldName, int type) Creates and returns a new FieldValueAccessor (by default, a ReflectionFieldValueAccessor) for the given target and fieldName.
static FieldValue	get(java.lang.Class targetClass) Retrieve a ClassExtension registered by registerClassExtension(...).
static FieldValue	get(java.lang.Object target)
abstract FieldValueAccessor	getAccessor(java.lang.Object target, java.lang.String fieldName, int type) Maintains a cache of FieldValueAccessor's for the instance by fieldName.
abstract java.lang.Object	getFieldValue(java.lang.Object target, FieldPath fieldPath) Recursively calls getFieldValuePrimitive() with the head of the fieldPath list.
static java.lang.Object	getFieldValue(java.lang.Object target, java.lang.String fieldPathString) Converts fieldPathString into a FieldPath (from a pool of shared FieldPaths) and calls getFieldValue(FieldPath).
abstract java.lang.Object	getFieldValuePrimitive(java.lang.Object target, FieldPath fieldPath) Gets the value from the reveiver using the fieldName indicated by fieldPath -- only the first node of the fieldPath is considered if it is a multi-node path.
void	populateFieldInfo(java.lang.Class targetClass, FieldInfo.Collection collection) Called by FieldInfo.fieldInfoForClass() to populate FieldInfo.Collection with information on available fields.
static void	registerClassExtension(java.lang.Class targetObjectClass, FieldValue fieldValueClassExtension) Put a ClassExtension implementation of the FieldValue interface into the cache of categories which is used to dispatch the FieldValue cover methods in this class.
abstract void	setFieldValue(java.lang.Object target, FieldPath fieldPath, java.lang.Object value) Recursively calls getFieldValuePrimitive() with the head of the fieldPath list up to the last fieldPath node and then calls setFieldValuePrimitive().
static void	setFieldValue(java.lang.Object target, java.lang.String fieldPathString, java.lang.Object value) Converts fieldPathString into a FieldPath (from a pool of shared FieldPaths) and calls setFieldValue(FieldPath, Object).
abstract void	setFieldValuePrimitive(java.lang.Object target, FieldPath fieldPath, java.lang.Object value) Sets the value on the reveiver using the fieldName indicated by fieldPath -- only the first node of the fieldPath is considered if it is a multi-node path.

Methods inherited from class ariba.util.core.ClassExtension

clone, forClass, getRealClass, setForClass

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

Setter

public static final int Setter

See Also:

Constant Field Values

Getter

public static final int Getter

See Also:

Constant Field Values

Constructor Detail

FieldValue

public FieldValue()

Method Detail

registerClassExtension

public static void registerClassExtension(java.lang.Class targetObjectClass,
                                          FieldValue fieldValueClassExtension)

Put a ClassExtension implementation of the FieldValue interface into the cache of categories which is used to dispatch the FieldValue cover methods in this class. Note that the FieldValue_Object will be cloned before caching, so you cannot depend upon getting back the exact same instance later with get(...).

Parameters:

targetObjectClass - the root class for which the classExtension applies

fieldValueClassExtension - the classExtension implementation of the FieldValue interface

get

public static FieldValue get(java.lang.Class targetClass)

Retrieve a ClassExtension registered by registerClassExtension(...). Note that this will clone the ClassExtension objects which are registered so that each subclass will have its own classExtension implementation. See ClassExtensionRegistry for details on this.

Parameters:

targetClass - the class for which a classExtension applies

Returns:

the classExtension which applies for the target

get

public static FieldValue get(java.lang.Object target)

setFieldValue

public static void setFieldValue(java.lang.Object target,
                                 java.lang.String fieldPathString,
                                 java.lang.Object value)

Converts fieldPathString into a FieldPath (from a pool of shared FieldPaths) and calls setFieldValue(FieldPath, Object).

Parameters:

target - see the FieldPath version of this method

fieldPathString - the dotted fieldPath String from which a shared FieldPath instance will be obtained

value - see the FieldPath version of this method

getFieldValue

public static java.lang.Object getFieldValue(java.lang.Object target,
                                             java.lang.String fieldPathString)

Converts fieldPathString into a FieldPath (from a pool of shared FieldPaths) and calls getFieldValue(FieldPath).

Parameters:

target - see the FieldPath version of this method

fieldPathString - the dotted fieldPath String from which a shared FieldPath instance will be obtained

Returns:

see the FieldPath version of this method

createAccessor

public abstract FieldValueAccessor createAccessor(java.lang.Object target,
                                                  java.lang.String fieldName,
                                                  int type)

Creates and returns a new FieldValueAccessor (by default, a ReflectionFieldValueAccessor) for the given target and fieldName. No caching is done by this method. This method is designed to be overridden by subclasses of FieldValue_Object which want to define their own specialized accessors. Note that the target is passed rather than its class so that accessors can be created at a finer granularity than class. Certain meta-data driven classes require this flexibility.

Parameters:

target - the object for which the accessor will be created

fieldName - the name of the field for which the accessor will be created

Returns:

a new FieldValueAccessor (ReflectionFieldValueAccessor by default)

getAccessor

public abstract FieldValueAccessor getAccessor(java.lang.Object target,
                                               java.lang.String fieldName,
                                               int type)

Maintains a cache of FieldValueAccessor's for the instance by fieldName. In general, all instances of a given class will share the same FieldValueAccessor for a given fieldName. However, certain meta-data driven classes may need to introspect upon the instance before returning the proper accessor.

Parameters:

target - the object for which the accessor will be looked up

fieldName - the name of the field for the accessor

Returns:

the cached FieldValueAccessor (ReflectionFieldValueAccessor by default)

setFieldValuePrimitive

public abstract void setFieldValuePrimitive(java.lang.Object target,
                                            FieldPath fieldPath,
                                            java.lang.Object value)

Sets the value on the reveiver using the fieldName indicated by fieldPath -- only the first node of the fieldPath is considered if it is a multi-node path.

Parameters:

target - the object on which the value will be set for the field identiifed by fieldPath

fieldPath - the fieldPath node (which contains a candidate accessor) to be used to set the value on target.

value - the value to set on the target

getFieldValuePrimitive

public abstract java.lang.Object getFieldValuePrimitive(java.lang.Object target,
                                                        FieldPath fieldPath)

Gets the value from the reveiver using the fieldName indicated by fieldPath -- only the first node of the fieldPath is considered if it is a multi-node path.

Parameters:

target - the object from which to get the value of the field identified by fieldPath

fieldPath - the fieldPath node which identifes the field to get.

Returns:

the value obtained from the target using the fieldPath

setFieldValue

public abstract void setFieldValue(java.lang.Object target,
                                   FieldPath fieldPath,
                                   java.lang.Object value)

Recursively calls getFieldValuePrimitive() with the head of the fieldPath list up to the last fieldPath node and then calls setFieldValuePrimitive(). Each time the recursion iterates, the receiver is the value of the previous getFieldValuePrimitive().

Parameters:

target - the object on which to start the recursion for setting the value using the fieldPath

fieldPath - the linked list of fieldPath nodes used to navigate from target to the final object in the chain, upon which the value is set

value - the value which is set on the final object in the chain

getFieldValue

public abstract java.lang.Object getFieldValue(java.lang.Object target,
                                               FieldPath fieldPath)

Recursively calls getFieldValuePrimitive() with the head of the fieldPath list. Each time the recursion iterates, the receiver is the value of the previous getFieldValuePrimitive().

Parameters:

target - the first object from which to start the recursion for getting the value identified by the fieldPath.

fieldPath - the linked list of fieldPath nodes that identifes the value to get

Returns:

the value obtained from the last object in the chain

populateFieldInfo

public void populateFieldInfo(java.lang.Class targetClass,
                              FieldInfo.Collection collection)

Called by FieldInfo.fieldInfoForClass() to populate FieldInfo.Collection with information on available fields. Implementing FieldValue extensions should callback with FieldInfo.Collection.updateFieldInfo() to provide information for all usable fields. Fields should be populated in a first-declaration-first manner -- i.e. super class before class, fields in java declaraion order where possible -- registration order is used to determine the "rank" recorded on the field.

Parameters:

targetClass - class for which info should be provided.

collection - repository to populate