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DeclarativeContract.java
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/**
* Copyright 2012-2021 The Feign Authors
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
* in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
package feign;
import feign.Contract.BaseContract;
import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.lang.reflect.Parameter;
import java.util.*;
import java.util.function.Predicate;
import java.util.stream.Collectors;
/**
* {@link Contract} base implementation that works by declaring witch annotations should be
* processed and how each annotation modifies {@link MethodMetadata}
*/
public abstract class DeclarativeContract extends BaseContract {
private final List<GuardedAnnotationProcessor> classAnnotationProcessors = new ArrayList<>();
private final List<GuardedAnnotationProcessor> methodAnnotationProcessors = new ArrayList<>();
private final Map<Class<Annotation>, DeclarativeContract.ParameterAnnotationProcessor<Annotation>> parameterAnnotationProcessors =
new HashMap<>();
@Override
public final List<MethodMetadata> parseAndValidateMetadata(Class<?> targetType) {
// any implementations must register processors
return super.parseAndValidateMetadata(targetType);
}
/**
* Called by parseAndValidateMetadata twice, first on the declaring class, then on the target type
* (unless they are the same).
*
* @param data metadata collected so far relating to the current java method.
* @param targetType the class to process
*/
@Override
protected final void processAnnotationOnClass(MethodMetadata data, Class<?> targetType) {
final List<GuardedAnnotationProcessor> processors = Arrays.stream(targetType.getAnnotations())
.flatMap(annotation -> classAnnotationProcessors.stream()
.filter(processor -> processor.test(annotation)))
.collect(Collectors.toList());
if (!processors.isEmpty()) {
Arrays.stream(targetType.getAnnotations())
.forEach(annotation -> processors.stream()
.filter(processor -> processor.test(annotation))
.forEach(processor -> processor.process(annotation, data)));
} else {
if (targetType.getAnnotations().length == 0) {
data.addWarning(String.format(
"Class %s has no annotations, it may affect contract %s",
targetType.getSimpleName(),
getClass().getSimpleName()));
} else {
data.addWarning(String.format(
"Class %s has annotations %s that are not used by contract %s",
targetType.getSimpleName(),
Arrays.stream(targetType.getAnnotations())
.map(annotation -> annotation.annotationType()
.getSimpleName())
.collect(Collectors.toList()),
getClass().getSimpleName()));
}
}
}
/**
* @param data metadata collected so far relating to the current java method.
* @param annotation annotations present on the current method annotation.
* @param method method currently being processed.
*/
@Override
protected final void processAnnotationOnMethod(MethodMetadata data,
Annotation annotation,
Method method) {
List<GuardedAnnotationProcessor> processors = methodAnnotationProcessors.stream()
.filter(processor -> processor.test(annotation))
.collect(Collectors.toList());
if (!processors.isEmpty()) {
processors.forEach(processor -> processor.process(annotation, data));
} else {
data.addWarning(String.format(
"Method %s has an annotation %s that is not used by contract %s",
method.getName(),
annotation.annotationType()
.getSimpleName(),
getClass().getSimpleName()));
}
}
/**
* @param data metadata collected so far relating to the current java method.
* @param annotations annotations present on the current parameter annotation.
* @param paramIndex if you find a name in {@code annotations}, call
* {@link #nameParam(MethodMetadata, String, int)} with this as the last parameter.
* @return true if you called {@link #nameParam(MethodMetadata, String, int)} after finding an
* http-relevant annotation.
*/
@Override
protected final boolean processAnnotationsOnParameter(MethodMetadata data,
Annotation[] annotations,
int paramIndex) {
List<Annotation> matchingAnnotations = Arrays.stream(annotations)
.filter(
annotation -> parameterAnnotationProcessors.containsKey(annotation.annotationType()))<
C1F5
/div>
.collect(Collectors.toList());
if (!matchingAnnotations.isEmpty()) {
matchingAnnotations.forEach(annotation -> parameterAnnotationProcessors
.getOrDefault(annotation.annotationType(), ParameterAnnotationProcessor.DO_NOTHING)
.process(annotation, data, paramIndex));
} else {
final Parameter parameter = data.method().getParameters()[paramIndex];
String parameterName = parameter.isNamePresent()
? parameter.getName()
: parameter.getType().getSimpleName();
if (annotations.length == 0) {
data.addWarning(String.format(
"Parameter %s has no annotations, it may affect contract %s",
parameterName,
getClass().getSimpleName()));
} else {
data.addWarning(String.format(
"Parameter %s has annotations %s that are not used by contract %s",
parameterName,
Arrays.stream(annotations)
.map(annotation -> annotation.annotationType()
.getSimpleName())
.collect(Collectors.toList()),
getClass().getSimpleName()));
}
}
return false;
}
/**
* Called while class annotations are being processed
*
* @param annotationType to be processed
* @param processor function that defines the annotations modifies {@link MethodMetadata}
*/
protected <E extends Annotation> void registerClassAnnotation(Class<E> annotationType,
DeclarativeContract.AnnotationProcessor<E> processor) {
registerClassAnnotation(
annotation -> annotation.annotationType().equals(annotationType),
processor);
}
/**
* Called while class annotations are being processed
*
* @param predicate to check if the annotation should be processed or not
* @param processor function that defines the annotations modifies {@link MethodMetadata}
*/
protected <E extends Annotation> void registerClassAnnotation(Predicate<E> predicate,
DeclarativeContract.AnnotationProcessor<E> processor) {
this.classAnnotationProcessors.add(new GuardedAnnotationProcessor(predicate, processor));
}
/**
* Called while method annotations are being processed
*
* @param annotationType to be processed
* @param processor function that defines the annotations modifies {@link MethodMetadata}
*/
protected <E extends Annotation> void registerMethodAnnotation(Class<E> annotationType,
DeclarativeContract.AnnotationProcessor<E> processor) {
registerMethodAnnotation(
annotation -> annotation.annotationType().equals(annotationType),
processor);
}
/**
* Called while method annotations are being processed
*
* @param predicate to check if the annotation should be processed or not
* @param processor function that defines the annotations modifies {@link MethodMetadata}
*/
protected <E extends Annotation> void registerMethodAnnotation(Predicate<E> predicate,
DeclarativeContract.AnnotationProcessor<E> processor) {
this.methodAnnotationProcessors.add(new GuardedAnnotationProcessor(predicate, processor));
}
/**
* Called while method parameter annotations are being processed
*
* @param annotation to be processed
* @param processor function that defines the annotations modifies {@link MethodMetadata}
*/
protected <E extends Annotation> void registerParameterAnnotation(Class<E> annotation,
DeclarativeContract.ParameterAnnotationProcessor<E> processor) {
this.parameterAnnotationProcessors.put((Class) annotation,
(DeclarativeContract.ParameterAnnotationProcessor) processor);
}
@FunctionalInterface
public interface AnnotationProcessor<E extends Annotation> {
/**
* @param annotation present on the current element.
* @param metadata collected so far relating to the current java method.
*/
void process(E annotation, MethodMetadata metadata);
}
@FunctionalInterface
public interface ParameterAnnotationProcessor<E extends Annotation> {
DeclarativeContract.ParameterAnnotationProcessor<Annotation> DO_NOTHING = (ann, data, i) -> {
};
/**
* @param annotation present on the current parameter annotation.
* @param metadata metadata collected so far relating to the current java method.
* @param paramIndex if you find a name in {@code annotations}, call
* {@link #nameParam(MethodMetadata, String, int)} with this as the last parameter.
* @return true if you called {@link #nameParam(MethodMetadata, String, int)} after finding an
* http-relevant annotation.
*/
void process(E annotation, MethodMetadata metadata, int paramIndex);
}
private class GuardedAnnotationProcessor
implements Predicate<Annotation>, DeclarativeContract.AnnotationProcessor<Annotation> {
private final Predicate<Annotation> predicate;
private final DeclarativeContract.AnnotationProcessor<Annotation> processor;
@SuppressWarnings({"rawtypes", "unchecked"})
private GuardedAnnotationProcessor(Predicate predicate,
DeclarativeContract.AnnotationProcessor processor) {
this.predicate = predicate;
this.processor = processor;
}
@Override
public void process(Annotation annotation, MethodMetadata metadata) {
processor.process(annotation, metadata);
}
@Override
public boolean test(Annotation t) {
return predicate.test(t);
}
}
}