GuardingDynamicLinker
public class BeansLinker extends Object implements GuardingDynamicLinker
DynamicLinkerFactory
so it is given the chance to link calls to all objects that no other linker recognized. Specifically, this linker will: record
, expose all public accessors of record components as property getters for StandardOperation.GET
operations in the StandardNamespace.PROPERTY
namespace;setXxx()
, getXxx()
, and isXxx()
as property setters and getters for StandardOperation.SET
and StandardOperation.GET
operations in the StandardNamespace.PROPERTY
namespace, except for getters for properties with names already handled by record component getters;StandardOperation.GET
operation in the StandardNamespace.METHOD
namespace; the methods thus retrieved can then be invoked using StandardOperation.CALL
.List
and Map
objects as StandardOperation.GET
and StandardOperation.SET
operations in the StandardNamespace.ELEMENT
namespace;List
and Map
objects as StandardOperation.REMOVE
operation in the StandardNamespace.ELEMENT
namespace;length
on Java arrays, Collection
and Map
objects;StandardOperation.NEW
on instances of StaticClass
as calls to constructors, including those static class objects that represent Java arrays (their constructors take a single int
parameter representing the length of the array to create);StaticClass
objects.static
on instances of Class
to access their StaticClass
.Overloaded method resolution is performed automatically for property setters, methods, and constructors. Additionally, manual overloaded method selection is supported by having a call site specify a name for a method that contains an explicit signature, e.g. StandardOperation.GET.withNamespace(METHOD).named("parseInt(String,int)")
You can use non-qualified class names in such signatures regardless of those classes' packages, they will match any class with the same non-qualified name. You only have to use a fully qualified class name in case non-qualified class names would cause selection ambiguity (that is extremely rare). Overloaded resolution for constructors is not automatic as there is no logical place to attach that functionality to but if a language wishes to provide this functionality, it can use getConstructorMethod(Class, String)
as a useful building block for it.
Variable argument invocation is handled for both methods and constructors.
Caller sensitive methods can be linked as long as they are otherwise public and link requests have call site descriptors carrying full-strength MethodHandles.Lookup
objects and not weakened lookups or the public lookup.
The behavior for handling missing members can be customized by passing a MissingMemberHandlerFactory
to the constructor
.
The class also exposes various methods for discovery of available property and method names on classes and class instances, as well as access to per-class linkers using the getLinkerForClass(Class)
method.
Constructor | Description |
---|---|
BeansLinker() |
Creates a new beans linker. |
BeansLinker |
Creates a new beans linker with the specified factory for creating missing member handlers. |
Modifier and Type | Method | Description |
---|---|---|
static Object |
getConstructorMethod |
Return the dynamic method of constructor of the given class and the given signature. |
GuardedInvocation |
getGuardedInvocation |
Creates a guarded invocation appropriate for a particular invocation with the specified arguments at a call site. |
static Set |
getInstanceMethodNames |
Returns a set of names of all instance methods of a class. |
TypeBasedGuardingDynamicLinker |
getLinkerForClass |
Returns a bean linker for a particular single class. |
static Set |
getReadableInstancePropertyNames |
Returns a set of names of all readable instance properties of a class. |
static Set |
getReadableStaticPropertyNames |
Returns a set of names of all readable static properties of a class. |
static Set |
getStaticMethodNames |
Returns a set of names of all static methods of a class. |
static Set |
getWritableInstancePropertyNames |
Returns a set of names of all writable instance properties of a class. |
static Set |
getWritableStaticPropertyNames |
Returns a set of names of all writable static properties of a class. |
static boolean |
isDynamicConstructor |
Returns true if the object is a Java constructor (obtained through getConstructorMethod(Class, String) }. |
static boolean |
isDynamicMethod |
Returns true if the object is a Java dynamic method (e.g., one obtained through a GET:METHOD operation on a Java object or StaticClass or through getConstructorMethod(Class, String) . |
public BeansLinker()
BeansLinker(MissingMemberHandlerFactory)
with null
passed as the missing member handler factory, resulting in the default behavior for linking and evaluating missing members.public BeansLinker(MissingMemberHandlerFactory missingMemberHandlerFactory)
MissingMemberHandlerFactory
for details.missingMemberHandlerFactory
- a factory for creating handlers for operations on missing members.public TypeBasedGuardingDynamicLinker getLinkerForClass(Class<?> clazz)
clazz
- the classpublic static boolean isDynamicMethod(Object obj)
GET:METHOD
operation on a Java object or StaticClass
or through getConstructorMethod(Class, String)
.obj
- the object we want to test for being a Java dynamic method.public static boolean isDynamicConstructor(Object obj)
getConstructorMethod(Class, String)
}.obj
- the object we want to test for being a Java constructor.public static Object getConstructorMethod(Class<?> clazz, String signature)
StaticClass
objects act as overloaded constructors without explicit signature selection. Example usage would be: getConstructorMethod(java.awt.Color.class, "int, int, int")
.clazz
- the classsignature
- full signature of the constructor. Note how you can use names of primitive types, array names with normal Java notation (e.g. "int[]"
), and normally you can even use unqualified class names (e.g. "String, List"
instead of "java.lang.String, java.util.List"
as long as they don't cause ambiguity in the specific parameter position.public static Set<String> getReadableInstancePropertyNames(Class<?> clazz)
clazz
- the classpublic static Set<String> getWritableInstancePropertyNames(Class<?> clazz)
clazz
- the classpublic static Set<String> getInstanceMethodNames(Class<?> clazz)
clazz
- the classpublic static Set<String> getReadableStaticPropertyNames(Class<?> clazz)
clazz
- the classpublic static Set<String> getWritableStaticPropertyNames(Class<?> clazz)
clazz
- the classpublic static Set<String> getStaticMethodNames(Class<?> clazz)
clazz
- the classpublic GuardedInvocation getGuardedInvocation(LinkRequest request, LinkerServices linkerServices) throws Exception
GuardingDynamicLinker
getGuardedInvocation
in interface GuardingDynamicLinker
request
- the object describing the request for linking a particular invocationlinkerServices
- linker servicesThrowable
subclass that describes an expected exception condition that also triggers relinking (often it is faster to rely on an infrequent but expected ClassCastException
than on an always evaluated instanceof
guard). While the linker must produce an invocation with parameter types matching those in the call site descriptor of the link request, it should not try to match the return type expected at the call site except when it can do it with only the conversions that lose neither precision nor magnitude, see LinkerServices.asTypeLosslessReturn(MethodHandle, MethodType)
for further explanation.Exception
- if the operation fails for whatever reason
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
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https://docs.oracle.com/en/java/javase/21/docs/api/jdk.dynalink/jdk/dynalink/beans/BeansLinker.html