Add FeignClientBuilder.Builder#customize(FeignBuilderCustomizer) (#499) (#515)

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/FeignClientBuilder.java

@@ -16,6 +16,7 @@
 
 package org.springframework.cloud.openfeign;
 
+import feign.Feign;
 import feign.hystrix.FallbackFactory;
 
 import org.springframework.context.ApplicationContext;
@@ -28,6 +29,7 @@ import org.springframework.context.ApplicationContext;
  *
  * @author Sven Döring
  * @author Matt King
+ * @author Sam Kruglov
  */
 public class FeignClientBuilder {
 
@@ -69,6 +71,19 @@ public class FeignClientBuilder {
 			return this;
 		}
 
+		/**
+		 * Applies a {@link FeignBuilderCustomizer} to the underlying {@link Feign.Builder}.
+		 * May be called multiple times.
+		 *
+		 * @param customizer applied in the same order as supplied here
+		 *                   after applying customizers found in the context.
+		 * @return the {@link Builder} with the customizer added
+		 */
+		public Builder<T> customize(final FeignBuilderCustomizer customizer) {
+			this.feignClientFactoryBean.addCustomizer(customizer);
+			return this;
+		}
+
 		public Builder<T> contextId(final String contextId) {
 			this.feignClientFactoryBean.setContextId(contextId);
 			return this;

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/FeignClientFactoryBean.java

@@ -17,6 +17,7 @@
 package org.springframework.cloud.openfeign;
 
 import java.util.ArrayList;
+import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -64,6 +65,7 @@ import org.springframework.util.StringUtils;
  * @author Olga Maciaszek-Sharma
  * @author Ilia Ilinykh
  * @author Marcin Grzejszczak
+ * @author Sam Kruglov
  */
 public class FeignClientFactoryBean implements FactoryBean<Object>, InitializingBean,
 		ApplicationContextAware, BeanFactoryAware {
@@ -103,6 +105,8 @@ public class FeignClientFactoryBean implements FactoryBean<Object>, Initializing
 
 	private boolean followRedirects = new Request.Options().isFollowRedirects();
 
+	private List<FeignBuilderCustomizer> additionalCustomizers = new ArrayList<>();
+
 	@Override
 	public void afterPropertiesSet() {
 		Assert.hasText(contextId, "Context id must be set");
@@ -138,6 +142,7 @@ public class FeignClientFactoryBean implements FactoryBean<Object>, Initializing
 					.forEach(feignBuilderCustomizer -> feignBuilderCustomizer
 							.customize(builder));
 		}
+		additionalCustomizers.forEach(customizer -> customizer.customize(builder));
 	}
 
 	protected void configureFeign(FeignContext context, Feign.Builder builder) {
@@ -494,6 +499,10 @@ public class FeignClientFactoryBean implements FactoryBean<Object>, Initializing
 		this.inheritParentContext = inheritParentContext;
 	}
 
+	public void addCustomizer(FeignBuilderCustomizer customizer) {
+		additionalCustomizers.add(customizer);
+	}
+
 	public ApplicationContext getApplicationContext() {
 		return applicationContext;
 	}

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/FeignBuilderCustomizerTests.java

@@ -33,6 +33,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * @author Matt King
+ * @author Sam Kruglov
  */
 public class FeignBuilderCustomizerTests {
 
@@ -78,6 +79,24 @@ public class FeignBuilderCustomizerTests {
 		context.close();
 	}
 
+	@Test
+	public void testBuildCustomizerOrderedWithAdditional() {
+		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(
+			FeignBuilderCustomizerTests.SampleConfiguration3.class);
+
+		FeignClientFactoryBean clientFactoryBean = context.getBean(FeignClientFactoryBean.class);
+		clientFactoryBean.addCustomizer(builder -> builder.logLevel(Logger.Level.BASIC));
+		clientFactoryBean.addCustomizer(Feign.Builder::doNotCloseAfterDecode);
+		FeignContext feignContext = context.getBean(FeignContext.class);
+
+		Feign.Builder builder = clientFactoryBean.feign(feignContext);
+		assertFeignBuilderField(builder, "logLevel", Logger.Level.BASIC);
+		assertFeignBuilderField(builder, "decode404", true);
+		assertFeignBuilderField(builder, "closeAfterDecode", false);
+
+		context.close();
+	}
+
 	private static FeignClientFactoryBean defaultFeignClientFactoryBean() {
 		FeignClientFactoryBean feignClientFactoryBean = new FeignClientFactoryBean();
 		feignClientFactoryBean.setContextId("test");

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/FeignClientBuilderTests.java

@@ -24,6 +24,7 @@ import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 
+import feign.Feign;
 import feign.hystrix.FallbackFactory;
 import org.hamcrest.Matchers;
 import org.junit.Before;
@@ -40,6 +41,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * @author Sven Döring
+ * @author Sam Kruglov
  */
 public class FeignClientBuilderTests {
 
@@ -56,10 +58,16 @@ public class FeignClientBuilderTests {
 		return method.getDefaultValue();
 	}
 
-	private static void assertFactoryBeanField(final FeignClientBuilder.Builder builder,
-			final String fieldName, final Object expectedValue) {
-		final Field factoryBeanField = ReflectionUtils
-				.findField(FeignClientBuilder.Builder.class, "feignClientFactoryBean");
+	private static void assertFactoryBeanField(final FeignClientBuilder.Builder builder, final String fieldName,
+		final Object expectedValue) {
+		final Object value = getFactoryBeanField(builder, fieldName);
+		assertThat(value).as("Expected value for the field '" + fieldName + "':").isEqualTo(expectedValue);
+	}
+
+	@SuppressWarnings("unchecked")
+	private static <T> T getFactoryBeanField(final FeignClientBuilder.Builder builder, final String fieldName) {
+		final Field factoryBeanField = ReflectionUtils.findField(FeignClientBuilder.Builder.class,
+			"feignClientFactoryBean");
 		ReflectionUtils.makeAccessible(factoryBeanField);
 		final FeignClientFactoryBean factoryBean = (FeignClientFactoryBean) ReflectionUtils
 				.getField(factoryBeanField, builder);
@@ -67,9 +75,7 @@ public class FeignClientBuilderTests {
 		final Field field = ReflectionUtils.findField(FeignClientFactoryBean.class,
 				fieldName);
 		ReflectionUtils.makeAccessible(field);
-		final Object value = ReflectionUtils.getField(field, factoryBean);
-		assertThat(value).as("Expected value for the field '" + fieldName + "':")
-				.isEqualTo(expectedValue);
+		return (T) ReflectionUtils.getField(field, factoryBean);
 	}
 
 	@Before
@@ -131,7 +137,8 @@ public class FeignClientBuilderTests {
 				.forType(TestFeignClient.class, "TestClient").inheritParentContext(false)
 				.fallback(TestFeignClientFallback.class)
 				.fallbackFactory(TestFeignClientFallbackFactory.class).decode404(true)
-				.url("Url/").path("/Path").contextId("TestContext");
+				.url("Url/").path("/Path").contextId("TestContext")
+			    .customize(Feign.Builder::doNotCloseAfterDecode);;
 
 		// then:
 		assertFactoryBeanField(builder, "applicationContext", this.applicationContext);
@@ -147,6 +154,8 @@ public class FeignClientBuilderTests {
 		assertFactoryBeanField(builder, "fallback", TestFeignClientFallback.class);
 		assertFactoryBeanField(builder, "fallbackFactory",
 				TestFeignClientFallbackFactory.class);
+		List<FeignBuilderCustomizer> additionalCustomizers = getFactoryBeanField(builder, "additionalCustomizers");
+		assertThat(additionalCustomizers).hasSize(1);
 	}
 
 	@Test