Adding gzip support for Spring Decoder (#230)

* Adding gzip support for Spring Decoder

* Restoring test config

* Switch to medium resource class in circleci. (#231)

* Adding gzip support for Spring Decoder

* Restoring test config

* Creating extra property for Gzip Decoder

* Fixing requested changes and updating doc

* Missed one change request

* Removing some properties

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/FeignAutoConfiguration.java

@@ -46,9 +46,11 @@ import org.springframework.cloud.commons.httpclient.ApacheHttpClientConnectionMa
 import org.springframework.cloud.commons.httpclient.ApacheHttpClientFactory;
 import org.springframework.cloud.commons.httpclient.OkHttpClientConnectionPoolFactory;
 import org.springframework.cloud.commons.httpclient.OkHttpClientFactory;
+import org.springframework.cloud.openfeign.support.DefaultGzipDecoderConfiguration;
 import org.springframework.cloud.openfeign.support.FeignHttpClientProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
 
 /**
  * @author Spencer Gibb
@@ -58,6 +60,7 @@ import org.springframework.context.annotation.Configuration;
 @ConditionalOnClass(Feign.class)
 @EnableConfigurationProperties({ FeignClientProperties.class,
 		FeignHttpClientProperties.class })
+@Import(DefaultGzipDecoderConfiguration.class)
 public class FeignAutoConfiguration {
 
 	@Autowired(required = false)

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/support/DefaultGzipDecoder.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2013-2019 the original author or 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
+ *
+ *      https://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 org.springframework.cloud.openfeign.support;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.lang.reflect.Type;
+import java.util.Collection;
+import java.util.zip.GZIPInputStream;
+
+import feign.FeignException;
+import feign.Response;
+import feign.Util;
+import feign.codec.Decoder;
+
+import org.springframework.cloud.openfeign.encoding.HttpEncoding;
+
+/**
+ * When response is compressed as gzip, this decompresses and uses {@link SpringDecoder}
+ * to decode.
+ *
+ * @author Jaesik Kim
+ */
+public class DefaultGzipDecoder implements Decoder {
+
+	private Decoder decoder;
+
+	public DefaultGzipDecoder(Decoder decoder) {
+		this.decoder = decoder;
+	}
+
+	@Override
+	public Object decode(final Response response, Type type)
+			throws IOException, FeignException {
+		Collection<String> encoding = response.headers()
+				.containsKey(HttpEncoding.CONTENT_ENCODING_HEADER)
+						? response.headers().get(HttpEncoding.CONTENT_ENCODING_HEADER)
+						: null;
+
+		if (encoding != null) {
+			if (encoding.contains(HttpEncoding.GZIP_ENCODING)) {
+				String decompressedBody = decompress(response);
+				if (decompressedBody != null) {
+					Response decompressedResponse = response.toBuilder()
+							.body(decompressedBody.getBytes()).build();
+					return decoder.decode(decompressedResponse, type);
+				}
+			}
+		}
+		return decoder.decode(response, type);
+	}
+
+	private String decompress(Response response) throws IOException {
+		if (response.body() == null) {
+			return null;
+		}
+		try (GZIPInputStream gzipInputStream = new GZIPInputStream(
+				response.body().asInputStream());
+				BufferedReader reader = new BufferedReader(
+						new InputStreamReader(gzipInputStream, Util.ISO_8859_1))) {
+			String outputString = "";
+			String line;
+			while ((line = reader.readLine()) != null) {
+				outputString += line;
+			}
+			return outputString;
+		}
+	}
+
+}

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/support/DefaultGzipDecoderConfiguration.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2013-2019 the original author or 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
+ *
+ *      https://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 org.springframework.cloud.openfeign.support;
+
+import feign.codec.Decoder;
+import feign.optionals.OptionalDecoder;
+
+import org.springframework.beans.factory.ObjectFactory;
+import org.springframework.boot.autoconfigure.AutoConfigureAfter;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
+import org.springframework.cloud.openfeign.FeignAutoConfiguration;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Configures Default Gzip Decoder.
+ *
+ * @author Jaesik Kim
+ */
+@Configuration
+@ConditionalOnProperty("feign.compression.response.enabled")
+// The OK HTTP client uses "transparent" compression.
+// If the accept-encoding header is present, it disables transparent compression
+@ConditionalOnMissingBean(type = "okhttp3.OkHttpClient")
+@AutoConfigureAfter(FeignAutoConfiguration.class)
+public class DefaultGzipDecoderConfiguration {
+
+	private ObjectFactory<HttpMessageConverters> messageConverters;
+
+	public DefaultGzipDecoderConfiguration(
+			ObjectFactory<HttpMessageConverters> messageConverters) {
+		this.messageConverters = messageConverters;
+	}
+
+	@Bean
+	@ConditionalOnMissingBean
+	@ConditionalOnProperty("feign.compression.response.useGzipDecoder")
+	public Decoder defaultGzipDecoder() {
+		return new OptionalDecoder(new ResponseEntityDecoder(
+				new DefaultGzipDecoder(new SpringDecoder(messageConverters))));
+	}
+
+}

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/support/SpringEncoder.java

@@ -35,6 +35,7 @@ import org.apache.commons.logging.LogFactory;
 
 import org.springframework.beans.factory.ObjectFactory;
 import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
+import org.springframework.cloud.openfeign.encoding.HttpEncoding;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpOutputMessage;
 import org.springframework.http.MediaType;
@@ -68,7 +69,8 @@ public class SpringEncoder implements Encoder {
 		// template.body(conversionService.convert(object, String.class));
 		if (requestBody != null) {
 			Class<?> requestType = requestBody.getClass();
-			Collection<String> contentTypes = request.headers().get("Content-Type");
+			Collection<String> contentTypes = request.headers()
+					.get(HttpEncoding.CONTENT_TYPE);
 
 			MediaType requestContentType = null;
 			if (contentTypes != null && !contentTypes.isEmpty()) {

spring-cloud-openfeign-core/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -26,6 +26,12 @@
 			"description": "Enables the response from Feign to be compressed.",
 			"defaultValue": "false"
 		},
+		{
+			"name": "feign.compression.response.useGzipDecoder",
+			"type": "java.lang.Boolean",
+			"description": "Enables the default gzip decoder to be used.",
+			"defaultValue": "false"
+		},
 		{
 			"name": "feign.compression.request.enabled",
 			"type": "java.lang.Boolean",

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/DefaultGzipDecoderTests.java

@@ -0,0 +1,159 @@
+/*
+ * Copyright 2013-2019 the original author or 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
+ *
+ *      https://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 org.springframework.cloud.openfeign;
+
+import java.util.Objects;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.cloud.openfeign.test.NoSecurityConfiguration;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Jaesik Kim
+ */
+@RunWith(SpringJUnit4ClassRunner.class)
+@SpringBootTest(classes = DefaultGzipDecoderTests.Application.class,
+		webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+		value = { "spring.application.name=defaultGzipDecoderTests",
+				"feign.compression.response.enabled=true",
+				"feign.compression.response.useGzipDecoder=true",
+				"feign.client.config.default.loggerLevel=full",
+				"logging.level.org.springframework.cloud.openfeign=DEBUG" })
+@DirtiesContext
+public class DefaultGzipDecoderTests extends FeignClientFactoryBean {
+
+	@Autowired
+	FeignContext context;
+
+	@Value("${local.server.port}")
+	private int port = 0;
+
+	public DefaultGzipDecoderTests() {
+		setName("tests");
+		setContextId("test");
+	}
+
+	public TestClient testClient() {
+		setType(this.getClass());
+		return feign(context).target(TestClient.class, "http://localhost:" + this.port);
+	}
+
+	@Test
+	public void testBodyDecompress() {
+		ResponseEntity<Hello> response = testClient().getGzipResponse();
+		assertThat(response).as("response was null").isNotNull();
+		assertThat(response.getStatusCode()).as("wrong status code")
+				.isEqualTo(HttpStatus.OK);
+		Hello hello = response.getBody();
+		assertThat(hello).as("hello was null").isNotNull();
+		assertThat(hello).as("first hello didn't match")
+				.isEqualTo(new Hello("hello world via response"));
+	}
+
+	@Test
+	public void testNullBodyDecompress() {
+		ResponseEntity<Hello> response = testClient().getNullResponse();
+		assertThat(response).as("response was null").isNotNull();
+		assertThat(response.getStatusCode()).as("wrong status code")
+				.isEqualTo(HttpStatus.OK);
+		Hello hello = response.getBody();
+		assertThat(hello).as("hello was not null").isNull();
+		assertThat(hello).as("null hello didn't match").isEqualTo(null);
+	}
+
+	private static class Hello {
+
+		private String message;
+
+		Hello() {
+		}
+
+		Hello(String message) {
+			this.message = message;
+		}
+
+		public String getMessage() {
+			return message;
+		}
+
+		public void setMessage(String message) {
+			this.message = message;
+		}
+
+		@Override
+		public boolean equals(Object o) {
+			if (this == o) {
+				return true;
+			}
+			if (o == null || getClass() != o.getClass()) {
+				return false;
+			}
+			Hello that = (Hello) o;
+			return Objects.equals(message, that.message);
+		}
+
+		@Override
+		public int hashCode() {
+			return Objects.hash(message);
+		}
+
+	}
+
+	protected interface TestClient {
+
+		@GetMapping("/helloGzipResponse")
+		ResponseEntity<Hello> getGzipResponse();
+
+		@GetMapping("/nullGzipResponse")
+		ResponseEntity<Hello> getNullResponse();
+
+	}
+
+	@Configuration
+	@EnableAutoConfiguration
+	@RestController
+	@Import(NoSecurityConfiguration.class)
+	protected static class Application implements TestClient {
+
+		@Override
+		public ResponseEntity<Hello> getGzipResponse() {
+			return ResponseEntity.ok(new Hello("hello world via response"));
+		}
+
+		@Override
+		public ResponseEntity<Hello> getNullResponse() {
+			return ResponseEntity.ok(null);
+		}
+
+	}
+
+}