org.dynamicvalues

Class Dynamic

java.lang.Object

org.dynamicvalues.Dynamic

public class Dynamic
extends Object

Dynamic value factory.

Dynamic Values

An object is a dynamic value if its graph contains only:

• primitives, primitive wrappers, or strings;
• lists of dynamic values (dynamic lists);
• maps whose keys and values are dynamic values (dynamic maps);

Dynamic values are suitable for generic manipulation with expression language or for generic object serialisations.

Value Copies

This factory takes an arbitrary object graph and returns its value copy (valueOf(Object)), i.e. a "copy" in which:

• maps and instances of user-defined types are replaced with dynamic maps;
• arrays and instances of Iterable types are replaced with dynamic lists;

External Value Copies

This factory can also produce external value copies (externalValueOf(Object), where dynamic lists and dynamic values are appropriately wrapped exclusively for JAXB serialisation. For this purpose, DynamicIO offers a JAXBContext pre-configured with wrapper classes:

 MyObject o = ...
 JAXBContext context = DynamicIO.newInstance();
 context.createMarshaller().marshal(Dynamic.externalValueOf(o),...sink...);
 

Deserialisation proceeds similarly, and valueOf(Object) can be invoked on the deserialised object to unwrap the external value copy into a normal value copy for further processing:

 JAXBContext context = DynamicIO.newInstance();
 Object externalValue = context.createUnmarshaller().unmarshal(...source...);
 Object value = valueOf(externalvalue);
  ...process value...
 

Assignments and Casts

valueOf(Object) and externalValueOf(Object) can be applied to any object, including lists, maps, wrapper types (hence primitive values, through auto-boxing). For this reason, the method signature returns a generic object, and the client is responsible for casting to the appropriate type if needed for further processing. However, a cast is performed implicitly on assignment, e.g.:

 MyObject o = ...
 Map value = Dynamic.valueOf(o);
 ...process value...
 

Copy Directives

This factory can follow Exclusion and Mapping directives to produce value copies and external value copies. By default, instance fields marked with the Exclude annotations are excluded from copies. Other directives can be conveniently produced by the Directives factory> As a simple example:

 
 import static ....Directives.*;
 
 MyObject o = ...
 Map value = Dynamic.valueOf(o,by().excluding(type(MyType.class),annotation(MyAnnotation.class)))
                                   .mapping(asString(QName.class));
 
 

Cycles and Sharing

Both value copies and external value copies preserve sharing and cycles. Note however that JAXB serialisation of external value copies does not support sharing and will fail in the presence of cycles. Similar restrictions may apply to other serialisation mechanisms, and more generally to other forms of later processing.

Author:

Fabio Simeoni

Constructor Summary

Constructors

Constructor and Description
Dynamic()

Method Summary

Methods

Modifier and Type	Method and Description
static <T> T	externalValueOf(Object o) Returns the value copy of an object in a form which is suitable for JAXB serialisation, based on default copy directives.
static <T> T	externalValueOf(Object o, Directives directives) Returns the value copy of an object in a form which is suitable for JAXB serialisation, based on given copy directives.
static <T> T	valueOf(Object o) Returns the value copy of an object based on default copy directives.
static <T> T	valueOf(Object o, Directives directives) Returns the value copy of an object based on given copy directives.

Methods inherited from class java.lang.Object

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

Constructor Detail

Dynamic

public Dynamic()

Method Detail

valueOf

public static <T> T valueOf(Object o)
                 throws Exception

Returns the value copy of an object based on default copy directives.

Parameters:

o - the object

Returns:

the dynamic value

Throws:

Exception - if the value copy of the object cannot be returned

valueOf

public static <T> T valueOf(Object o,
            Directives directives)
                 throws Exception

Returns the value copy of an object based on given copy directives.

Parameters:

o - the object

directives - the copy directives

Returns:

the dynamic value

Throws:

Exception - if the value copy of the object cannot be returned

externalValueOf

public static <T> T externalValueOf(Object o)
                         throws Exception

Returns the value copy of an object in a form which is suitable for JAXB serialisation, based on default copy directives.

Parameters:

o - the object

Returns:

the dynamic value

Throws:

Exception - if the value copy of the object cannot be returned

externalValueOf

public static <T> T externalValueOf(Object o,
                    Directives directives)
                         throws Exception

Returns the value copy of an object in a form which is suitable for JAXB serialisation, based on given copy directives.

Parameters:

o - the object

directives - the copy directives

Returns:

the dynamic value

Throws:

Exception - if the value copy of the object cannot be returned