Create a LoadBalancerClient abstraction and a Ribbon implementation

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/client/ServiceInstance.java

+package org.springframework.cloud.client;
+
+
+/**
+ * @author Spencer Gibb
+ * TODO: name? Server? HostAndPort? Instance?
+ */
+public interface ServiceInstance {
+    public String getHost();
+    public int getPort();
+}

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/client/loadbalancer/LoadBalancerClient.java

+package org.springframework.cloud.client.loadbalancer;
+
+import org.springframework.cloud.client.ServiceInstance;
+
+/**
+ * @author Spencer Gibb
+ */
+public interface LoadBalancerClient {
+    /**
+     * Choose a {@see ServiceInstance} from the LoadBalancer for the specified service
+     * @param serviceId The serviceId to use to look up the LoadBalancer
+     * @return
+     */
+    public ServiceInstance choose(String serviceId);
+}

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

@@ -3,6 +3,7 @@ package org.springframework.cloud.netflix.ribbon;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
 import org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration;
 import org.springframework.cloud.netflix.eureka.EurekaRibbonInitializer;
 import org.springframework.context.annotation.Bean;
@@ -10,7 +11,6 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.http.client.ClientHttpRequestInterceptor;
 import org.springframework.web.client.RestTemplate;
 
-import javax.annotation.PostConstruct;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -27,19 +27,22 @@ public class RibbonAutoConfiguration {
 
     @Bean
     @ConditionalOnMissingBean(RestTemplate.class)
-    public RestTemplate restTemplate() {
-        return new RestTemplate();
+    public RestTemplate restTemplate(RibbonInterceptor ribbonInterceptor) {
+        RestTemplate restTemplate = new RestTemplate();
+        List<ClientHttpRequestInterceptor> list = new ArrayList<>();
+        list.add(ribbonInterceptor);
+        restTemplate.setInterceptors(list);
+        return restTemplate;
     }
 
     @Bean
-    public RibbonInterceptor ribbonInterceptor() {
-        return new RibbonInterceptor();
+    @ConditionalOnMissingBean(LoadBalancerClient.class)
+    public LoadBalancerClient loadBalancerClient() {
+        return new RibbonLoadBalancerClient();
     }
 
-    @PostConstruct
-    public void init() {
-        List<ClientHttpRequestInterceptor> list = new ArrayList<>();
-        list.add(ribbonInterceptor());
-        restTemplate().setInterceptors(list);
+    @Bean
+    public RibbonInterceptor ribbonInterceptor(LoadBalancerClient loadBalancerClient) {
+        return new RibbonInterceptor(loadBalancerClient);
     }
 }

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

 package org.springframework.cloud.netflix.ribbon;
 
-import com.netflix.client.ClientFactory;
-import com.netflix.loadbalancer.ILoadBalancer;
-import com.netflix.loadbalancer.Server;
+import org.springframework.cloud.client.ServiceInstance;
+import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
 import org.springframework.http.HttpRequest;
 import org.springframework.http.client.ClientHttpRequestExecution;
 import org.springframework.http.client.ClientHttpRequestInterceptor;
@@ -17,6 +16,13 @@ import java.net.URI;
  * @author Spencer Gibb
  */
 public class RibbonInterceptor implements ClientHttpRequestInterceptor {
+
+    private LoadBalancerClient loadBalancer;
+
+    public RibbonInterceptor(LoadBalancerClient loadBalancer) {
+        this.loadBalancer = loadBalancer;
+    }
+
     @Override
     public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {
         HttpRequestWrapper wrapper = new HttpRequestWrapper(request) {
@@ -24,14 +30,10 @@ public class RibbonInterceptor implements ClientHttpRequestInterceptor {
             public URI getURI() {
                 URI originalUri = super.getURI();
                 String serviceName = originalUri.getHost();
-                ILoadBalancer loadBalancer = ClientFactory.getNamedLoadBalancer(serviceName);
-                Server server = loadBalancer.chooseServer(null);
-                if (server == null) {
-                    throw new IllegalStateException("Unable to locate ILoadBalancer for service: "+ serviceName);
-                }
+                ServiceInstance instance = loadBalancer.choose(serviceName);
                 URI uri = UriComponentsBuilder.fromUri(originalUri)
-                        .host(server.getHost())
-                        .port(server.getPort())
+                        .host(instance.getHost())
+                        .port(instance.getPort())
                         .build()
                         .toUri();
                 return uri;

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

+package org.springframework.cloud.netflix.ribbon;
+
+import com.netflix.client.ClientFactory;
+import com.netflix.loadbalancer.ILoadBalancer;
+import com.netflix.loadbalancer.Server;
+import org.springframework.cloud.client.ServiceInstance;
+import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
+
+/**
+ * @author Spencer Gibb
+ */
+public class RibbonLoadBalancerClient implements LoadBalancerClient {
+    @Override
+    public ServiceInstance choose(String serviceId) {
+        ILoadBalancer loadBalancer = ClientFactory.getNamedLoadBalancer(serviceId);
+        Server server = loadBalancer.chooseServer(null);
+        if (server == null) {
+            throw new IllegalStateException("Unable to locate ILoadBalancer for service: "+ serviceId);
+        }
+        return new RibbonServer(server);
+    }
+
+    private class RibbonServer implements ServiceInstance {
+        private Server server;
+
+        private RibbonServer(Server server) {
+            this.server = server;
+        }
+
+        @Override
+        public String getHost() {
+            return server.getHost();
+        }
+
+        @Override
+        public int getPort() {
+            return server.getPort();
+        }
+    }
+}