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StreamDecoder.java
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132 lines (116 loc) · 4.06 KB
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/*
* Copyright © 2012 The Feign Authors (feign@commonhaus.dev)
*
* 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.stream;
import static feign.Util.ensureClosed;
import feign.FeignException;
import feign.Response;
import feign.codec.Decoder;
import java.io.Closeable;
import java.io.IOException;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.Iterator;
import java.util.Optional;
import java.util.Spliterators;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
/**
* Iterator based decoder that support streaming.
*
* <p>
*
* <p>Example: <br>
*
* <pre>
* <code>
* Feign.builder()
* .decoder(StreamDecoder.create(JacksonIteratorDecoder.create()))
* .doNotCloseAfterDecode() // Required for streaming
* .target(GitHub.class, "https://api.github.com");
* or
* Feign.builder()
* .decoder(StreamDecoder.create(JacksonIteratorDecoder.create(), (r, t) -> "hello world")))
* .doNotCloseAfterDecode() // Required for streaming
* .target(GitHub.class, "https://api.github.com");
* interface GitHub {
* {@literal @}RequestLine("GET /repos/{owner}/{repo}/contributors")
* Stream<Contributor> contributors(@Param("owner") String owner, @Param("repo") String repo);
* }</code>
* </pre>
*/
public final class StreamDecoder implements Decoder {
private final Decoder iteratorDecoder;
private final Optional<Decoder> delegateDecoder;
StreamDecoder(Decoder iteratorDecoder, Decoder delegateDecoder) {
this.iteratorDecoder = iteratorDecoder;
this.delegateDecoder = Optional.ofNullable(delegateDecoder);
}
@Override
public Object decode(Response response, Type type) throws IOException, FeignException {
if (!isStream(type)) {
if (!delegateDecoder.isPresent()) {
throw new IllegalArgumentException(
"StreamDecoder supports types other than stream. "
+ "When type is not stream, the delegate decoder needs to be setting.");
} else {
return delegateDecoder.get().decode(response, type);
}
}
ParameterizedType streamType = (ParameterizedType) type;
Iterator<?> iterator =
(Iterator<?>) iteratorDecoder.decode(response, new IteratorParameterizedType(streamType));
return StreamSupport.stream(Spliterators.spliteratorUnknownSize(iterator, 0), false)
.onClose(
() -> {
if (iterator instanceof Closeable) {
ensureClosed((Closeable) iterator);
} else {
ensureClosed(response);
}
});
}
public static boolean isStream(Type type) {
if (!(type instanceof ParameterizedType)) {
return false;
}
ParameterizedType parameterizedType = (ParameterizedType) type;
return parameterizedType.getRawType().equals(Stream.class);
}
public static StreamDecoder create(Decoder iteratorDecoder) {
return new StreamDecoder(iteratorDecoder, null);
}
public static StreamDecoder create(Decoder iteratorDecoder, Decoder delegateDecoder) {
return new StreamDecoder(iteratorDecoder, delegateDecoder);
}
static final class IteratorParameterizedType implements ParameterizedType {
private final ParameterizedType streamType;
IteratorParameterizedType(ParameterizedType streamType) {
this.streamType = streamType;
}
@Override
public Type[] getActualTypeArguments() {
return streamType.getActualTypeArguments();
}
@Override
public Type getRawType() {
return Iterator.class;
}
@Override
public Type getOwnerType() {
return null;
}
}
}