feature Encoder/Decoder supports Fastjson2 (#2368)

* feature Encoder/Decoder supports Fastjson2

* add Fastjson2 to the mind map

README.md

@@ -474,6 +474,23 @@ public class Example {
 
 NB: you may also need to add `SOAPErrorDecoder` if SOAP Faults are returned in response with error http codes (4xx, 5xx, ...)
 
+#### Fastjson2 
+
+[fastjson2](./fastjson2) includes an encoder and decoder you can use with a JSON API.
+
+Add `Fastjson2Encoder` and/or `Fastjson2Decoder` to your `Feign.Builder` like so:
+
+```java
+public class Example {
+  public static void main(String[] args) {
+      GitHub github = Feign.builder()
+                     .encoder(new Fastjson2Encoder())
+                     .decoder(new Fastjson2Decoder())
+                     .target(GitHub.class, "https://api.github.com");
+  }
+}
+```
+
 ### Contract
 
 #### JAX-RS

fastjson2/README.md

@@ -0,0 +1,22 @@
+Fastjson2 Codec
+===================
+
+This module adds support for encoding and decoding JSON via Fastjson2.
+
+Add `Fastjson2Encoder` and/or `Fastjson2Decoder` to your `Feign.Builder` like so:
+
+```java
+GitHub github = Feign.builder()
+                     .encoder(new Fastjson2Encoder())
+                     .decoder(new Fastjson2Decoder())
+                     .target(GitHub.class, "https://api.github.com");
+```
+
+If you want to customize, provide it to the `Fastjson2Encoder` and `Fastjson2Decoder`:
+
+```java
+GitHub github = Feign.builder()
+                     .encoder(new Fastjson2Encoder(new JSONWriter.Feature[]{JSONWriter.Feature.WriteNonStringValueAsString})
+                     .decoder(new Fastjson2Decoder(new JSONReader.Feature[]{JSONReader.Feature.EmptyStringAsNull}))
+                     .target(GitHub.class, "https://api.github.com");
+```

fastjson2/pom.xml

@@ -0,0 +1,52 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    Copyright 2012-2024 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>13.3-SNAPSHOT</version>
+  </parent>
+
+  <artifactId>feign-fastjson2</artifactId>
+  <name>Feign Fastjson2</name>
+  <description>Feign Fastjson2</description>
+
+  <properties>
+    <main.basedir>${project.basedir}/..</main.basedir>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>${project.groupId}</groupId>
+      <artifactId>feign-core</artifactId>
+    </dependency>
+
+    <dependency>
+      <groupId>com.alibaba.fastjson2</groupId>
+      <artifactId>fastjson2</artifactId>
+    </dependency>
+
+    <dependency>
+      <groupId>${project.groupId}</groupId>
+      <artifactId>feign-core</artifactId>
+      <type>test-jar</type>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+</project>

fastjson2/src/main/java/feign/fastjson2/Fastjson2Decoder.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2012-2024 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.fastjson2;
+
+import static feign.Util.ensureClosed;
+
+import com.alibaba.fastjson2.JSON;
+import com.alibaba.fastjson2.JSONException;
+import com.alibaba.fastjson2.JSONReader;
+import feign.FeignException;
+import feign.Response;
+import feign.Util;
+import feign.codec.Decoder;
+import java.io.IOException;
+import java.io.Reader;
+import java.lang.reflect.Type;
+
+/**
+ * @author changjin wei(魏昌进)
+ */
+public class Fastjson2Decoder implements Decoder {
+
+  private final JSONReader.Feature[] features;
+
+  public Fastjson2Decoder() {
+    this(new JSONReader.Feature[0]);
+  }
+
+  public Fastjson2Decoder(JSONReader.Feature[] features) {
+    this.features = features;
+  }
+
+  @Override
+  public Object decode(Response response, Type type) throws IOException, FeignException {
+    if (response.status() == 404 || response.status() == 204) return Util.emptyValueOf(type);
+    if (response.body() == null) return null;
+    Reader reader = response.body().asReader(response.charset());
+    try {
+      return JSON.parseObject(reader, type, features);
+    } catch (JSONException e) {
+      if (e.getCause() != null && e.getCause() instanceof IOException) {
+        throw IOException.class.cast(e.getCause());
+      }
+      throw e;
+    } finally {
+      ensureClosed(reader);
+    }
+  }
+}

fastjson2/src/main/java/feign/fastjson2/Fastjson2Encoder.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2012-2024 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.fastjson2;
+
+import com.alibaba.fastjson2.JSON;
+import com.alibaba.fastjson2.JSONWriter;
+import feign.RequestTemplate;
+import feign.Util;
+import feign.codec.EncodeException;
+import feign.codec.Encoder;
+import java.lang.reflect.Type;
+
+/**
+ * @author changjin wei(魏昌进)
+ */
+public class Fastjson2Encoder implements Encoder {
+
+  private final JSONWriter.Feature[] features;
+
+  public Fastjson2Encoder() {
+    this(new JSONWriter.Feature[0]);
+  }
+
+  public Fastjson2Encoder(JSONWriter.Feature[] features) {
+    this.features = features;
+  }
+
+  @Override
+  public void encode(Object object, Type bodyType, RequestTemplate template)
+      throws EncodeException {
+    template.body(JSON.toJSONBytes(object, features), Util.UTF_8);
+  }
+}