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79 lines (70 loc) · 2.75 KB
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/**
* Copyright 2012-2020 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.reactive;
import feign.Contract;
import feign.MethodMetadata;
import feign.Types;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;
import java.util.stream.Stream;
import org.reactivestreams.Publisher;
public class ReactiveDelegatingContract implements Contract {
private final Contract delegate;
ReactiveDelegatingContract(Contract delegate) {
this.delegate = delegate;
}
@Override
public List<MethodMetadata> parseAndValidateMetadata(Class<?> targetType) {
List<MethodMetadata> methodsMetadata = this.delegate.parseAndValidateMetadata(targetType);
for (final MethodMetadata metadata : methodsMetadata) {
final Type type = metadata.returnType();
if (!isReactive(type)) {
throw new IllegalArgumentException(String.format(
"Method %s of contract %s doesn't returns a org.reactivestreams.Publisher",
metadata.configKey(), targetType.getSimpleName()));
}
/*
* we will need to change the return type of the method to match the return type contained
* within the Publisher
*/
Type[] actualTypes = ((ParameterizedType) type).getActualTypeArguments();
if (actualTypes.length > 1) {
throw new IllegalStateException("Expected only one contained type.");
} else {
Class<?> actual = Types.getRawType(actualTypes[0]);
if (Stream.class.isAssignableFrom(actual)) {
throw new IllegalArgumentException(
"Streams are not supported when using Reactive Wrappers");
}
metadata.returnType(actualTypes[0]);
}
}
return methodsMetadata;
}
/**
* Ensure that the type provided implements a Reactive Streams Publisher.
*
* @param type to inspect.
* @return true if the type implements the Reactive Streams Publisher specification.
*/
private boolean isReactive(Type type) {
if (!ParameterizedType.class.isAssignableFrom(type.getClass())) {
return false;
}
ParameterizedType parameterizedType = (ParameterizedType) type;
Class<?> raw = (Class<?>) parameterizedType.getRawType();
return Publisher.class.isAssignableFrom(raw);
}
}