Introduces feign-java8 (OpenFeign#548)

arielsegura · adriancole · commit d7f40f5a3692 · 2017-05-06T11:11:34.000+08:00
Introduces `feign-java8` with support for `java.util.Optional`
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,4 +1,5 @@
 ### Version 9.5
+* Introduces `feign-java8` with support for `java.util.Optional`
 * Adds `Feign.Builder.mapAndDecode()` to allow response preprocessing before decoding it.
 
 ### Version 9.4.1
diff --git a/java8/pom.xml b/java8/pom.xml
@@ -0,0 +1,42 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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">
+    <parent>
+        <artifactId>parent</artifactId>
+        <groupId>io.github.openfeign</groupId>
+        <version>9.4.1-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>feign-java8</artifactId>
+    <name>Feign Java 8</name>
+    <description>Feign Java 8</description>
+
+    <properties>
+        <!-- override default bytecode version for src/main from parent pom -->
+        <main.java.version>1.8</main.java.version>
+        <main.signature.artifact>java18</main.signature.artifact>
+        <main.basedir>${project.basedir}/..</main.basedir>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>feign-core</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>feign-gson</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.squareup.okhttp3</groupId>
+            <artifactId>mockwebserver</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>
diff --git a/java8/src/main/java/feign/optionals/OptionalDecoder.java b/java8/src/main/java/feign/optionals/OptionalDecoder.java
@@ -0,0 +1,40 @@
+package feign.optionals;
+
+import feign.Response;
+import feign.Util;
+import feign.codec.Decoder;
+
+import java.io.IOException;
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+import java.util.Objects;
+import java.util.Optional;
+
+public final class OptionalDecoder implements Decoder {
+    final Decoder delegate;
+
+    public OptionalDecoder(Decoder delegate) {
+        Objects.requireNonNull(delegate, "Decoder must not be null. ");
+        this.delegate = delegate;
+    }
+
+    @Override public Object decode(Response response, Type type) throws IOException {
+        if(!isOptional(type)) {
+            return delegate.decode(response, type);
+        }
+
+        if(response.status() == 404) {
+            return Optional.empty();
+        }
+        Type enclosedType = Util.resolveLastTypeParameter(type, Optional.class);
+        return Optional.of(delegate.decode(response, enclosedType));
+    }
+
+    static boolean isOptional(Type type) {
+        if(!(type instanceof ParameterizedType)) {
+            return false;
+        }
+        ParameterizedType parameterizedType = (ParameterizedType) type;
+        return parameterizedType.getRawType().equals(Optional.class);
+    }
+}
diff --git a/java8/src/test/java/feign/optionals/OptionalDecoderTests.java b/java8/src/test/java/feign/optionals/OptionalDecoderTests.java
@@ -0,0 +1,36 @@
+package feign.optionals;
+
+import feign.Feign;
+import feign.RequestLine;
+import feign.codec.Decoder;
+import okhttp3.mockwebserver.MockResponse;
+import okhttp3.mockwebserver.MockWebServer;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.util.Optional;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class OptionalDecoderTests {
+
+    interface OptionalInterface {
+        @RequestLine("GET /")
+        Optional<String> get();
+    }
+
+    @Test
+    public void simpleOptionalTest() throws IOException, InterruptedException {
+        MockWebServer server = new MockWebServer();
+        server.enqueue(new MockResponse().setResponseCode(404));
+        server.enqueue(new MockResponse().setBody("foo"));
+
+        OptionalInterface api = Feign.builder()
+                .decode404()
+                .decoder(new OptionalDecoder(new Decoder.Default()))
+                .target(OptionalInterface.class, server.url("/").toString());
+
+        assertThat(api.get().isPresent()).isFalse();
+        assertThat(api.get().get()).isEqualTo("foo");
+    }
+}
diff --git a/pom.xml b/pom.xml
@@ -20,6 +20,7 @@
     <module>ribbon</module>
     <module>sax</module>
     <module>slf4j</module>
+    <module>java8</module>
   </modules>
 
   <properties>

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,5 @@`
`1`	`1`	`### Version 9.5`
	`2`	+* Introduces `feign-java8` with support for `java.util.Optional`
`2`	`3`	* Adds `Feign.Builder.mapAndDecode()` to allow response preprocessing before decoding it.
`3`	`4`
`4`	`5`	`### Version 9.4.1`