Package io.opentelemetry.instrumentation.api.annotation.support

Class AnnotationReflectionHelper

java.lang.Object

io.opentelemetry.instrumentation.api.annotation.support.AnnotationReflectionHelper

public class AnnotationReflectionHelper
extends Object

Helper class for reflecting over annotations at runtime..

Method Summary

Modifier and Type	Method	Description
static <A extends Annotation,T> Function<A,T>	bindAnnotationElementMethod(MethodHandles.Lookup lookup, Class<? extends Annotation> annotationClass, String methodName, Class<T> returnClass)	Binds a lambda of the functional interface Function<A extends Annotation, T> to the element of an Annotation class by name which, when invoked with an instance of that annotation, will return the value of that element.
static Class<? extends Annotation>	forNameOrNull(ClassLoader classLoader, String className)	Returns the Class<? extends Annotation> for the name of the Annotation at runtime, otherwise returns null.

Methods inherited from class java.lang.Object

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

Method Detail

forNameOrNull

@Nullable
public static Class<? extends Annotation> forNameOrNull(ClassLoader classLoader,
                                                        String className)

Returns the Class<? extends Annotation> for the name of the Annotation at runtime, otherwise returns null.

bindAnnotationElementMethod

public static <A extends Annotation,T> Function<A,T> bindAnnotationElementMethod(MethodHandles.Lookup lookup,
                                                                                             Class<? extends Annotation> annotationClass,
                                                                                             String methodName,
                                                                                             Class<T> returnClass)
                                                                                      throws Throwable

Binds a lambda of the functional interface Function<A extends Annotation, T> to the element of an Annotation class by name which, when invoked with an instance of that annotation, will return the value of that element.

For example, calling this method as follows:

 Function<WithSpan, String> function = AnnotationReflectionHelper.bindAnnotationElementMethod(
     MethodHandles.lookup(),
     WithSpan.class,
     "value",
     String.class);
 

is equivalent to the following Java code:

 Function<WithSpan, String> function = WithSpan::value;
 

Type Parameters:

A - the type of the annotation

T - the type of the annotation element

Parameters:

lookup - the MethodHandles.Lookup of the calling method, e.g. MethodHandles.lookup()

annotationClass - the Class of the Annotation

methodName - name of the annotation element method

returnClass - type of the annotation element

Returns:

Instance of Function<Annotation, T> that is bound to the annotation element method

Throws:

NoSuchMethodException - the annotation element method was not found

Throwable - on failing to bind to the