- Functional Interface:
- This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
@FunctionalInterface public interface MissingMemberHandlerFactory
A factory for creating method handles for linking missing member behavior in
BeansLinker. BeansLinker links these method handles into guarded invocations for link requests specifying
StandardOperations when it is either certain or possible that the requested member (property, method, or element) is missing. They will be linked both for
namedand unnamed operations. The implementer must ensure that the parameter types of the returned method handle match the parameter types of the call site described in the link request. The return types can differ, though, to allow
DynamicLinkerFactory.setPrelinkTransformer(jdk.dynalink.linker.GuardedInvocationTransformer)late return type transformations}. It is allowed to return
nullfor a method handle if the default behavior is sufficient.
Default missing member behaviorWhen a
BeansLinkeris configured without a missing member handler factory, or the factory returns
nullfor a particular handler creation invocation, the default behavior is used. The default behavior is to return
GuardingDynamicLinker.getGuardedInvocation(LinkRequest, LinkerServices)when it can be determined at link time that the linked operation will never address an existing member. This lets the
DynamicLinkerattempt the next linker if there is one, or ultimately fail the link request with
NoSuchDynamicMethodException. For other cases (typically all unnamed member operations as well as most named operations on collection elements)
BeansLinkerwill produce a conditional linkage that will return
nullwhen invoked at runtime with a name that does not match any member for getters and silently ignore the passed values for setters.
Implementing exception-throwing behaviorNote that if the language-specific behavior for an operation on a missing member is to throw an exception then the factory should produce a method handle that throws the exception when invoked, and must not throw an exception itself, as the linkage for the missing member is often conditional.
- See Also:
Modifier and Type Method Description
createMissingMemberHandler(LinkRequest linkRequest, LinkerServices linkerServices)Returns a method handle suitable for implementing missing member behavior for a particular link request.
createMissingMemberHandlerMethodHandle createMissingMemberHandler(LinkRequest linkRequest, LinkerServices linkerServices) throws ExceptionReturns a method handle suitable for implementing missing member behavior for a particular link request. See the class description for details.
linkRequest- the current link request
linkerServices- the current link services
- a method handle that can be invoked if the property, element, or method being addressed by an operation is missing. The return value can be null.
Exception- if the operation fails for any reason. Please observe the class documentation notes for implementing exception-throwing missing member behavior.