DefaultWebFilterChain is a top-level, public class

Issue: SPR-15348

spring-web/src/main/java/org/springframework/web/server/handler/DefaultWebFilterChain.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2002-2017 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
+ *
+ *      http://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.web.server.handler;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import reactor.core.publisher.Mono;
+
+import org.springframework.util.Assert;
+import org.springframework.util.ObjectUtils;
+import org.springframework.web.server.ServerWebExchange;
+import org.springframework.web.server.WebFilter;
+import org.springframework.web.server.WebFilterChain;
+import org.springframework.web.server.WebHandler;
+
+/**
+ * Default implementation of {@link WebFilterChain}.
+ *
+ * @author Rossen Stoyanchev
+ * @since 5.0
+ */
+public class DefaultWebFilterChain implements WebFilterChain {
+
+	private final List<WebFilter> filters;
+
+	private final WebHandler handler;
+
+	private volatile int index;
+
+
+	public DefaultWebFilterChain(WebHandler handler, WebFilter... filters) {
+		Assert.notNull(handler, "WebHandler is required");
+		this.filters = ObjectUtils.isEmpty(filters) ? Collections.emptyList() : Arrays.asList(filters);
+		this.handler = handler;
+	}
+
+
+	@Override
+	public Mono<Void> filter(ServerWebExchange exchange) {
+		if (this.index < this.filters.size()) {
+			WebFilter filter = this.filters.get(this.index++);
+			return filter.filter(exchange, this);
+		}
+		else {
+			return this.handler.handle(exchange);
+		}
+	}
+
+}

spring-web/src/main/java/org/springframework/web/server/handler/FilteringWebHandler.java

@@ -16,14 +16,15 @@
 
 package org.springframework.web.server.handler;
 
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 
 import reactor.core.publisher.Mono;
 
+import org.springframework.util.CollectionUtils;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.WebFilter;
-import org.springframework.web.server.WebFilterChain;
 import org.springframework.web.server.WebHandler;
 
 /**
@@ -35,7 +36,7 @@ import org.springframework.web.server.WebHandler;
  */
 public class FilteringWebHandler extends WebHandlerDecorator {
 
-	private final List<WebFilter> filters;
+	private final WebFilter[] filters;
 
 
 	/**
@@ -44,41 +45,24 @@ public class FilteringWebHandler extends WebHandlerDecorator {
 	 */
 	public FilteringWebHandler(WebHandler webHandler, List<WebFilter> filters) {
 		super(webHandler);
-		this.filters = Collections.unmodifiableList(filters);
+		this.filters = !CollectionUtils.isEmpty(filters) ?
+				filters.toArray(new WebFilter[filters.size()]) : new WebFilter[0];
 	}
 
 
 	/**
-	 * Return read-only list of the configured filters.
+	 * Return a read-only list of the configured filters.
 	 */
 	public List<WebFilter> getFilters() {
-		return this.filters;
+		return Arrays.asList(this.filters);
 	}
 
 
 	@Override
 	public Mono<Void> handle(ServerWebExchange exchange) {
-		if (this.filters.isEmpty()) {
-			return super.handle(exchange);
-		}
-		return new DefaultWebFilterChain().filter(exchange);
-	}
-
-
-	private class DefaultWebFilterChain implements WebFilterChain {
-
-		private int index;
-
-		@Override
-		public Mono<Void> filter(ServerWebExchange exchange) {
-			if (this.index < filters.size()) {
-				WebFilter filter = filters.get(this.index++);
-				return filter.filter(exchange, this);
-			}
-			else {
-				return getDelegate().handle(exchange);
-			}
-		}
+		return this.filters.length != 0 ?
+				new DefaultWebFilterChain(getDelegate(), this.filters).filter(exchange) :
+				super.handle(exchange);
 	}
 
 }