allow feign to decode parameterized types. Added SpringDecoderTests.

fixes gh-57

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/feign/SpringDecoder.java

@@ -2,6 +2,7 @@ package org.springframework.cloud.netflix.feign;
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
 
 import org.springframework.beans.factory.annotation.Autowired;
@@ -31,18 +32,17 @@ public class SpringDecoder implements Decoder {
 
 	@Override
 	public Object decode(final Response response, Type type) throws IOException, FeignException {
-		if (type instanceof Class) {
-			@SuppressWarnings({ "unchecked", "rawtypes" })
-			HttpMessageConverterExtractor<?> extractor = new HttpMessageConverterExtractor(
-					(Class<?>) type, messageConverters.getConverters());
+		if (type instanceof Class || type instanceof ParameterizedType) {
+            @SuppressWarnings({ "unchecked", "rawtypes" })
+            HttpMessageConverterExtractor<?> extractor = new HttpMessageConverterExtractor(
+                    type, messageConverters.getConverters());
 
-			Object data = extractor.extractData(new FeignResponseAdapter(response));
-			return data;
-		}
-		throw new DecodeException("type is not an instance of Class: " + type);
+            return extractor.extractData(new FeignResponseAdapter(response));
+        }
+		throw new DecodeException("type is not an instance of Class or ParameterizedType: " + type);
 	}
 
-	private class FeignResponseAdapter implements ClientHttpResponse {
+    private class FeignResponseAdapter implements ClientHttpResponse {
 		private final Response response;
 
 		private FeignResponseAdapter(Response response) {

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/feign/SpringDecoderTests.java

@@ -0,0 +1,111 @@
+package org.springframework.cloud.netflix.feign;
+
+import static org.junit.Assert.*;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.boot.test.IntegrationTest;
+import org.springframework.boot.test.SpringApplicationConfiguration;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.web.WebAppConfiguration;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * @author Spencer Gibb
+ */
+@RunWith(SpringJUnit4ClassRunner.class)
+@SpringApplicationConfiguration(classes = SpringDecoderTests.Application.class)
+@WebAppConfiguration
+@IntegrationTest({ "server.port=0", "spring.application.name=springdecodertest", "spring.jmx.enabled=true" })
+public class SpringDecoderTests extends FeignConfigurer {
+
+    @Value("${local.server.port}")
+    private int port = 0;
+
+    public TestClient testClient() {
+        return feign().target(TestClient.class, "http://localhost:"+port);
+    }
+
+    protected static interface TestClient {
+        @RequestMapping(method = RequestMethod.GET, value = "/hello")
+        public Hello getHello();
+
+        @RequestMapping(method = RequestMethod.GET, value = "/hellos")
+        public List<Hello> getHellos();
+
+        @RequestMapping(method = RequestMethod.GET, value = "/hellostrings")
+        public List<String> getHelloStrings();
+    }
+
+    @Configuration
+    @EnableAutoConfiguration
+    @RestController
+    protected static class Application implements TestClient {
+
+        public Hello getHello() {
+            return new Hello("hello world 1");
+        }
+
+        public List<Hello> getHellos() {
+            ArrayList<Hello> hellos = new ArrayList<>();
+            hellos.add(new Hello("hello world 1"));
+            hellos.add(new Hello("oi terra 2"));
+            return hellos;
+        }
+
+        public List<String> getHelloStrings() {
+            ArrayList<String> hellos = new ArrayList<>();
+            hellos.add("hello world 1");
+            hellos.add("oi terra 2");
+            return hellos;
+        }
+
+        public static void main(String[] args) {
+            new SpringApplicationBuilder(Application.class).properties(
+                    "spring.application.name=springdecodertest", "management.contextPath=/admin")
+                    .run(args);
+        }
+    }
+
+    @Test
+    public void testSimpleType() {
+        Hello hello = testClient().getHello();
+        assertNotNull("hello was null", hello);
+        assertEquals("first hello didn't match", new Hello("hello world 1"), hello);
+    }
+
+    @Test
+    public void testUserParameterizedTypeDecode() {
+        List<Hello> hellos = testClient().getHellos();
+        assertNotNull("hellos was null", hellos);
+        assertEquals("hellos was not the right size", 2, hellos.size());
+        assertEquals("first hello didn't match", new Hello("hello world 1"), hellos.get(0));
+    }
+
+    @Test
+    public void testSimpleParameterizedTypeDecode() {
+        List<String> hellos = testClient().getHelloStrings();
+        assertNotNull("hellos was null", hellos);
+        assertEquals("hellos was not the right size", 2, hellos.size());
+        assertEquals("first hello didn't match", "hello world 1", hellos.get(0));
+    }
+
+    @Data
+    @AllArgsConstructor
+    @NoArgsConstructor
+    public static class Hello {
+        private String message;
+    }
+}