Add builder for WebGraphQlHandler

To allow adding more options when creating a WebGraphQlHandler.

See gh-53

graphql-spring-boot-starter/src/main/java/org/springframework/graphql/boot/WebFluxGraphQlAutoConfiguration.java

@@ -65,7 +65,9 @@ public class WebFluxGraphQlAutoConfiguration {
 	@Bean
 	@ConditionalOnMissingBean
 	public WebGraphQlHandler webGraphQlHandler(ObjectProvider<WebInterceptor> interceptors, GraphQlService service) {
-		return WebInterceptor.createHandler(interceptors.orderedStream().collect(Collectors.toList()), service);
+		return WebGraphQlHandler.builder(service)
+				.interceptors(interceptors.orderedStream().collect(Collectors.toList()))
+				.build();
 	}
 
 	@Bean

graphql-spring-boot-starter/src/main/java/org/springframework/graphql/boot/WebMvcGraphQlAutoConfiguration.java

@@ -71,7 +71,9 @@ public class WebMvcGraphQlAutoConfiguration {
 	@Bean
 	@ConditionalOnMissingBean
 	public WebGraphQlHandler webGraphQlHandler(ObjectProvider<WebInterceptor> interceptors, GraphQlService service) {
-		return WebInterceptor.createHandler(interceptors.orderedStream().collect(Collectors.toList()), service);
+		return WebGraphQlHandler.builder(service)
+				.interceptors(interceptors.orderedStream().collect(Collectors.toList()))
+				.build();
 	}
 
 	@Bean

spring-graphql/src/main/java/org/springframework/graphql/web/DefaultWebGraphQlHandlerBuilder.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2002-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.graphql.web;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import graphql.ExecutionInput;
+
+import org.springframework.graphql.GraphQlService;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+
+/**
+ * Default implementation of {@link WebGraphQlHandler.Builder}.
+ */
+class DefaultWebGraphQlHandlerBuilder implements WebGraphQlHandler.Builder {
+
+	private final GraphQlService service;
+
+	@Nullable
+	private List<WebInterceptor> interceptors;
+
+
+	DefaultWebGraphQlHandlerBuilder(GraphQlService service) {
+		Assert.notNull(service, "GraphQlService must not be null");
+		this.service = service;
+	}
+
+
+	@Override
+	public WebGraphQlHandler.Builder interceptors(List<WebInterceptor> interceptors) {
+		this.interceptors = (this.interceptors != null ? this.interceptors : new ArrayList<>());
+		this.interceptors.addAll(interceptors);
+		return this;
+	}
+
+	@Override
+	public WebGraphQlHandler build() {
+		List<WebInterceptor> interceptorsToUse =
+				(this.interceptors != null ? this.interceptors : Collections.emptyList());
+
+		return interceptorsToUse.stream()
+				.reduce(WebInterceptor::andThen)
+				.map(interceptor -> (WebGraphQlHandler) input -> interceptor.intercept(input, createHandler()))
+				.orElse(createHandler());
+	}
+
+	private WebGraphQlHandler createHandler() {
+		return webInput -> {
+			ExecutionInput input = webInput.toExecutionInput();
+			return this.service.execute(input).map(result -> new WebOutput(webInput, result));
+		};
+	}
+
+}

spring-graphql/src/test/java/org/springframework/graphql/web/WebInterceptorTests.java

@@ -50,7 +50,8 @@ public class WebInterceptorTests {
 		WebInput input = new WebInput(
 				URI.create("/"), new HttpHeaders(), Collections.singletonMap("query", "any"), "1");
 
-		WebOutput output = WebInterceptor.createHandler(interceptors, service).handle(input).block();
+		WebOutput output = WebGraphQlHandler.builder(service).interceptors(interceptors).build()
+				.handle(input).block();
 
 		assertThat(sb.toString()).isEqualTo(":pre1:pre2:pre3:post3:post2:post1");
 		assertThat(output.getResponseHeaders().get("name")).containsExactly("value3", "value2", "value1");

spring-graphql/src/test/java/org/springframework/graphql/web/webflux/GraphQlWebSocketHandlerTests.java

@@ -272,11 +272,12 @@ public class GraphQlWebSocketHandlerTests {
 	}
 
 	private GraphQlWebSocketHandler initWebSocketHandler(
-			@Nullable List<WebInterceptor> interceptors, @Nullable Duration initTimeoutDuration) throws Exception {
+			@Nullable List<WebInterceptor> interceptors, @Nullable Duration initTimeoutDuration) {
 
-		WebGraphQlHandler graphQlHandler = WebInterceptor.createHandler(
-				(interceptors != null ? interceptors : Collections.emptyList()),
-				new ExecutionGraphQlService(graphQlSource()));
+		WebGraphQlHandler graphQlHandler =
+				WebGraphQlHandler.builder(new ExecutionGraphQlService(graphQlSource()))
+						.interceptors(interceptors != null ? interceptors : Collections.emptyList())
+						.build();
 
 		return new GraphQlWebSocketHandler(graphQlHandler,
 				ServerCodecConfigurer.create(),

spring-graphql/src/test/java/org/springframework/graphql/web/webmvc/GraphQlWebSocketHandlerTests.java

@@ -258,9 +258,10 @@ public class GraphQlWebSocketHandlerTests {
 			@Nullable List<WebInterceptor> interceptors, @Nullable Duration initTimeoutDuration) {
 
 		try {
-			WebGraphQlHandler graphQlHandler = WebInterceptor.createHandler(
-					(interceptors != null ? interceptors : Collections.emptyList()),
-					new ExecutionGraphQlService(graphQlSource()));
+			WebGraphQlHandler graphQlHandler =
+					WebGraphQlHandler.builder(new ExecutionGraphQlService(graphQlSource()))
+							.interceptors(interceptors != null ? interceptors : Collections.emptyList())
+							.build();
 
 			return new GraphQlWebSocketHandler(graphQlHandler, converter,
 					(initTimeoutDuration != null ? initTimeoutDuration : Duration.ofSeconds(60)));