More robust instantiation in SpringClientFactory

SpringClientFactory returns null if the class is not aware of IClientConfig.

This change catches the exception when trying the constructor with IClientConfig so classes that aren't aware of IClientConfig can be created.

Fixes gh-1608

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/ribbon/SpringClientFactory.java

@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.netflix.ribbon;
 
+import java.lang.reflect.Constructor;
+
 import org.springframework.beans.BeanUtils;
 import org.springframework.cloud.context.named.NamedContextFactory;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
@@ -80,33 +82,30 @@ public class SpringClientFactory extends NamedContextFactory<RibbonClientSpecifi
 	static <C> C instantiateWithConfig(AnnotationConfigApplicationContext context,
 										Class<C> clazz, IClientConfig config) {
 		C result = null;
-		if (IClientConfigAware.class.isAssignableFrom(clazz)) {
-			IClientConfigAware obj = (IClientConfigAware) BeanUtils.instantiate(clazz);
-			obj.initWithNiwsConfig(config);
-			@SuppressWarnings("unchecked")
-			C value = (C) obj;
-			result = value;
+		
+		try {
+			Constructor<C> constructor = clazz.getConstructor(IClientConfig.class);
+			result = constructor.newInstance(config);
+		} catch (Throwable e) {
+			// Ignored
 		}
-		else {
-			try {
-				if (clazz.getConstructor(IClientConfig.class) != null) {
-					result = clazz.getConstructor(IClientConfig.class)
-							.newInstance(config);
-				}
-				else {
-					result = BeanUtils.instantiate(clazz);
-				}
+		
+		if (result == null) {
+			result = BeanUtils.instantiate(clazz);
+			
+			if (result instanceof IClientConfigAware) {
+				((IClientConfigAware) result).initWithNiwsConfig(config);
 			}
-			catch (Throwable ex) {
-				// NOPMD
+			
+			if (context != null) {
+				context.getAutowireCapableBeanFactory().autowireBean(result);
 			}
 		}
-		if (context != null) {
-			context.getAutowireCapableBeanFactory().autowireBean(result);
-		}
+		
 		return result;
 	}
 
+	@Override
 	public <C> C getInstance(String name, Class<C> type) {
 		C instance = super.getInstance(name, type);
 		if (instance != null) {

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/ribbon/SpringClientFactoryTests.java

@@ -23,9 +23,13 @@ import org.springframework.cloud.netflix.archaius.ArchaiusAutoConfiguration;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 
 import com.netflix.client.DefaultLoadBalancerRetryHandler;
+import com.netflix.client.IClientConfigAware;
+import com.netflix.client.config.DefaultClientConfigImpl;
+import com.netflix.client.config.IClientConfig;
 import com.netflix.niws.client.http.RestClient;
 import com.sun.jersey.client.apache4.ApacheHttpClient4;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.Assert.assertEquals;
 import static org.springframework.boot.test.util.EnvironmentTestUtils.addEnvironment;
 
@@ -35,6 +39,31 @@ import static org.springframework.boot.test.util.EnvironmentTestUtils.addEnviron
  */
 public class SpringClientFactoryTests {
 
+	public static class ClientConfigInjectedByConstructor {
+		
+		private IClientConfig clientConfig;
+
+		public ClientConfigInjectedByConstructor(IClientConfig clientConfig) {
+			this.clientConfig = clientConfig;
+		}
+	}
+	
+	public static class ClientConfigInjectedByInitMethod implements IClientConfigAware {
+		
+		private IClientConfig clientConfig;
+
+		@Override
+		public void initWithNiwsConfig(IClientConfig clientConfig) {
+			this.clientConfig = clientConfig;
+		}
+	}
+	
+	public static class NoClientConfigAware {
+		
+		public NoClientConfigAware() {
+			// no client config
+		}
+	}
 
 	@Test
 	public void testConfigureRetry() {
@@ -65,4 +94,25 @@ public class SpringClientFactoryTests {
 				.getHttpClient().getParams().getParameter(ClientPNames.COOKIE_POLICY));
 		factory.destroy();
 	}
+	
+	@Test
+	public void testInstantiateWithConfigInjectByConstructor() {
+		IClientConfig clientConfig = new DefaultClientConfigImpl();
+		ClientConfigInjectedByConstructor instance = SpringClientFactory.instantiateWithConfig(ClientConfigInjectedByConstructor.class, clientConfig);
+		assertThat(instance.clientConfig).isSameAs(clientConfig);
+	}
+	
+	@Test
+	public void testInstantiateWithConfigInjectedByInitMethod() {
+		IClientConfig clientConfig = new DefaultClientConfigImpl();
+		ClientConfigInjectedByInitMethod instance = SpringClientFactory.instantiateWithConfig(ClientConfigInjectedByInitMethod.class, clientConfig);
+		assertThat(instance.clientConfig).isSameAs(clientConfig);
+	}
+	
+	@Test
+	public void testInstantiateWithoutConfig() {
+		IClientConfig clientConfig = new DefaultClientConfigImpl();
+		NoClientConfigAware instance = SpringClientFactory.instantiateWithConfig(NoClientConfigAware.class, clientConfig);
+		assertThat(instance).isNotNull();
+	}
 }