Add JSON-java decoder and encoder

json/README.md

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+JSON-java Codec
+===================
+
+This module adds support for encoding and decoding [JSON][] via [JSON-java][].
+
+Add `JsonEncoder` and/or `JsonDecoder` to your `Feign.Builder` like so:
+
+```java
+api = Feign.builder()
+           .decoder(new JsonDecoder())
+           .encoder(new JsonEncoder())
+           .target(GitHub.class, "https://api");
+```
+
+[JSON]: https://www.json.org/json-en.html
+[JSON-java]: https://github.com/stleary/JSON-java

json/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    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.
+
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <parent>
+    <groupId>io.github.openfeign</groupId>
+    <artifactId>parent</artifactId>
+    <version>11.3-SNAPSHOT</version>
+  </parent>
+
+  <artifactId>feign-json</artifactId>
+  <name>Feign JSON-java</name>
+  <description>Feign JSON-java</description>
+
+  <properties>
+    <main.basedir>${project.basedir}/..</main.basedir>
+    <hamcrest.version>1.3</hamcrest.version>
+    <mockito.version>1.10.19</mockito.version>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>${project.groupId}</groupId>
+      <artifactId>feign-core</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.json</groupId>
+      <artifactId>json</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.hamcrest</groupId>
+      <artifactId>hamcrest-core</artifactId>
+      <version>${hamcrest.version}</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.hamcrest</groupId>
+      <artifactId>hamcrest-library</artifactId>
+      <version>${hamcrest.version}</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.mockito</groupId>
+      <artifactId>mockito-all</artifactId>
+      <version>${mockito.version}</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>${project.groupId}</groupId>
+      <artifactId>feign-mock</artifactId>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+</project>

json/src/main/java/feign/json/JsonDecoder.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.json;
+
+import feign.Response;
+import feign.codec.DecodeException;
+import feign.codec.Decoder;
+import org.json.JSONArray;
+import org.json.JSONException;
+import org.json.JSONObject;
+import org.json.JSONTokener;
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.Reader;
+import java.lang.reflect.Type;
+import static feign.Util.UTF_8;
+import static java.lang.String.format;
+
+/**
+ * Decodes responses using JSON-java.
+ * <p>
+ * Basic example with {@link feign.Feign.Builder}:
+ *
+ * <pre>
+ *   interface GitHub {
+ *
+ *     {@literal @}RequestLine("GET /repos/{owner}/{repo}/contributors")
+ *     JSONArray contributors({@literal @}Param("owner") String owner, {@literal @}Param("repo") String repo);
+ *
+ *   }
+ *
+ *   GitHub github = Feign.builder()
+ *                      .decoder(new JsonDecoder())
+ *                      .target(GitHub.class, "https://api.github.com");
+ *
+ *   JSONArray contributors = github.contributors("openfeign", "feign");
+ *
+ *   System.out.println(contributors.getJSONObject(0).getString("login"));
+ * </pre>
+ */
+public class JsonDecoder implements Decoder {
+
+  @Override
+  public Object decode(Response response, Type type) throws IOException, DecodeException {
+    if (response.body() == null)
+      return null;
+    try (Reader reader = response.body().asReader(response.charset())) {
+      Reader bodyReader = (reader.markSupported()) ? reader : new BufferedReader(reader);
+      bodyReader.mark(1);
+      if (bodyReader.read() == -1) {
+        return null; // Empty body
+      }
+      bodyReader.reset();
+      return decodeJSON(response, type, bodyReader);
+    } catch (JSONException jsonException) {
+      if (jsonException.getCause() != null && jsonException.getCause() instanceof IOException) {
+        throw (IOException) jsonException.getCause();
+      }
+      throw new DecodeException(response.status(), jsonException.getMessage(), response.request(),
+          jsonException);
+    }
+  }
+
+  private Object decodeJSON(Response response, Type type, Reader reader) {
+    JSONTokener tokenizer = new JSONTokener(reader);
+    if (JSONObject.class.isAssignableFrom((Class<?>) type))
+      return new JSONObject(tokenizer);
+    else if (JSONArray.class.isAssignableFrom((Class<?>) type))
+      return new JSONArray(tokenizer);
+    else
+      throw new DecodeException(response.status(),
+          format("%s is not a type supported by this decoder.", type), response.request());
+  }
+
+}

json/src/main/java/feign/json/JsonEncoder.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.json;
+
+import feign.RequestTemplate;
+import feign.codec.EncodeException;
+import feign.codec.Encoder;
+import org.json.JSONArray;
+import org.json.JSONObject;
+import java.lang.reflect.Type;
+import static java.lang.String.format;
+
+/**
+ * Encodes requests using JSON-java.
+ * <p>
+ * Basic example with {@link feign.Feign.Builder}:
+ *
+ * <pre>
+ *   interface GitHub {
+ *
+ *     {@literal @}RequestLine("POST /repos/{owner}/{repo}/contributors")
+ *     JSONObject create({@literal @}Param("owner") String owner,
+ *                       {@literal @}@Param("repo") String repo,
+ *                       JSONObject contributor);
+ *
+ *   }
+ *
+ *   GitHub github = Feign.builder()
+ *                      .decoder(new JsonDecoder())
+ *                      .encoder(new JsonEncoder())
+ *                      .target(GitHub.class, "https://api.github.com");
+ *
+ *   JSONObject contributor = new JSONObject();
+ *
+ *   contributor.put("login", "radio-rogal");
+ *   contributor.put("contributions", 0);
+ *   github.create("openfeign", "feign", contributor);
+ * </pre>
+ */
+public class JsonEncoder implements Encoder {
+
+  @Override
+  public void encode(Object object, Type bodyType, RequestTemplate template)
+      throws EncodeException {
+    if (object == null)
+      return;
+    if (object instanceof JSONArray || object instanceof JSONObject) {
+      template.body(object.toString());
+    } else {
+      throw new EncodeException(format("%s is not a type supported by this encoder.", bodyType));
+    }
+  }
+
+}

json/src/test/java/feign/json/JsonCodecTest.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.json;
+
+import feign.Feign;
+import feign.Param;
+import feign.Request;
+import feign.RequestLine;
+import feign.mock.HttpMethod;
+import feign.mock.MockClient;
+import feign.mock.MockTarget;
+import org.json.JSONArray;
+import org.json.JSONObject;
+import org.junit.Before;
+import org.junit.Test;
+import java.io.IOException;
+import java.io.InputStream;
+import static feign.Util.toByteArray;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.hasSize;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
+
+interface GitHub {
+
+  @RequestLine("GET /repos/{owner}/{repo}/contributors")
+  JSONArray contributors(@Param("owner") String owner, @Param("repo") String repo);
+
+  @RequestLine("POST /repos/{owner}/{repo}/contributors")
+  JSONObject create(@Param("owner") String owner,
+                    @Param("repo") String repo,
+                    JSONObject contributor);
+
+}
+
+
+public class JsonCodecTest {
+
+  private GitHub github;
+  private MockClient mockClient;
+
+  @Before
+  public void setUp() {
+    mockClient = new MockClient();
+    github = Feign.builder()
+        .decoder(new JsonDecoder())
+        .encoder(new JsonEncoder())
+        .client(mockClient)
+        .target(new MockTarget<>(GitHub.class));
+  }
+
+  @Test
+  public void decodes() throws IOException {
+    try (InputStream input = getClass().getResourceAsStream("/fixtures/contributors.json")) {
+      byte[] response = toByteArray(input);
+      mockClient.ok(HttpMethod.GET, "/repos/openfeign/feign/contributors", response);
+      JSONArray contributors = github.contributors("openfeign", "feign");
+      assertThat(contributors.toList(), hasSize(30));
+      contributors.forEach(contributor -> ((JSONObject) contributor).getString("login"));
+    }
+  }
+
+  @Test
+  public void encodes() {
+    JSONObject contributor = new JSONObject();
+    contributor.put("login", "radio-rogal");
+    contributor.put("contributions", 0);
+    mockClient.ok(HttpMethod.POST, "/repos/openfeign/feign/contributors",
+        "{\"login\":\"radio-rogal\",\"contributions\":0}");
+    JSONObject response = github.create("openfeign", "feign", contributor);
+    Request request = mockClient.verifyOne(HttpMethod.POST, "/repos/openfeign/feign/contributors");
+    assertNotNull(request.body());
+    String json = new String(request.body());
+    assertThat(json, containsString("\"login\":\"radio-rogal\""));
+    assertThat(json, containsString("\"contributions\":0"));
+    assertEquals("radio-rogal", response.getString("login"));
+    assertEquals(0, response.getInt("contributions"));
+  }
+
+}