Apply "instanceof pattern matching" in spring-webflux

This commit also applies additional clean-up tasks such as the following.

- final fields
- diamond operator (<>) for anonymous inner classes
- multi-catch

This has only been applied to `src/main/java`.

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/DefaultClientResponseBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * 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.
@@ -66,7 +66,7 @@ final class DefaultClientResponseBuilder implements ClientResponse.Builder {
 	};
 
 
-	private ExchangeStrategies strategies;
+	private final ExchangeStrategies strategies;
 
 	private int statusCode = 200;
 
@@ -104,8 +104,8 @@ final class DefaultClientResponseBuilder implements ClientResponse.Builder {
 			this.headers.addAll(other.headers().asHttpHeaders());
 		}
 		this.originalResponse = other;
-		this.request = (other instanceof DefaultClientResponse ?
-				((DefaultClientResponse) other).request() : EMPTY_REQUEST);
+		this.request = (other instanceof DefaultClientResponse defaultClientResponse ?
+				defaultClientResponse.request() : EMPTY_REQUEST);
 	}
 
 

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/ExchangeFilterFunctions.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * 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.
@@ -116,8 +116,7 @@ public abstract class ExchangeFilterFunctions {
 	public static ExchangeFilterFunction basicAuthentication() {
 		return (request, next) -> {
 			Object attr = request.attributes().get(BASIC_AUTHENTICATION_CREDENTIALS_ATTRIBUTE);
-			if (attr instanceof Credentials) {
-				Credentials cred = (Credentials) attr;
+			if (attr instanceof Credentials cred) {
 				return next.exchange(ClientRequest.from(request)
 						.headers(headers -> headers.setBasicAuth(cred.username, cred.password))
 						.build());
@@ -174,10 +173,9 @@ public abstract class ExchangeFilterFunctions {
 			if (this == other) {
 				return true;
 			}
-			if (!(other instanceof Credentials)) {
+			if (!(other instanceof Credentials otherCred)) {
 				return false;
 			}
-			Credentials otherCred = (Credentials) other;
 			return (this.username.equals(otherCred.username) && this.password.equals(otherCred.password));
 		}
 

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/ChangePathPatternParserVisitor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * 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.
@@ -70,8 +70,7 @@ class ChangePathPatternParserVisitor implements RouterFunctions.Visitor {
 	}
 
 	private void changeParser(RequestPredicate predicate) {
-		if (predicate instanceof Target) {
-			Target target = (Target) predicate;
+		if (predicate instanceof Target target) {
 			target.changeParser(this.parser);
 		}
 	}

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/DefaultEntityResponseBuilder.java

@@ -195,7 +195,7 @@ class DefaultEntityResponseBuilder<T> implements EntityResponse.Builder<T> {
 
 	@Override
 	public Mono<EntityResponse<T>> build() {
-		return Mono.just(new DefaultEntityResponse<T>(
+		return Mono.just(new DefaultEntityResponse<>(
 				this.status, this.headers, this.cookies, this.entity, this.inserter, this.hints));
 	}
 

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/DefaultServerRequestBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * 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.
@@ -69,7 +69,7 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 
 	private final List<HttpMessageReader<?>> messageReaders;
 
-	private ServerWebExchange exchange;
+	private final ServerWebExchange exchange;
 
 	private String methodName;
 

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/DefaultServerResponseBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * 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.
@@ -78,8 +78,7 @@ class DefaultServerResponseBuilder implements ServerResponse.BodyBuilder {
 		Assert.notNull(other, "ServerResponse must not be null");
 		this.headers.addAll(other.headers());
 		this.cookies.addAll(other.cookies());
-		if (other instanceof AbstractServerResponse) {
-			AbstractServerResponse abstractOther = (AbstractServerResponse) other;
+		if (other instanceof AbstractServerResponse abstractOther) {
 			this.statusCode = abstractOther.statusCode;
 			this.hints.putAll(abstractOther.hints);
 		}

spring-webflux/src/main/java/org/springframework/web/reactive/handler/AbstractUrlHandlerMapping.java

@@ -153,8 +153,7 @@ public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping {
 		Object handler = this.handlerMap.get(pattern);
 
 		// Bean name or resolved handler?
-		if (handler instanceof String) {
-			String handlerName = (String) handler;
+		if (handler instanceof String handlerName) {
 			handler = obtainApplicationContext().getBean(handlerName);
 		}
 
@@ -223,8 +222,7 @@ public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping {
 		}
 
 		// Eagerly resolve handler if referencing singleton via name.
-		if (!this.lazyInitHandlers && handler instanceof String) {
-			String handlerName = (String) handler;
+		if (!this.lazyInitHandlers && handler instanceof String handlerName) {
 			if (obtainApplicationContext().isSingleton(handlerName)) {
 				resolvedHandler = obtainApplicationContext().getBean(handlerName);
 			}

spring-webflux/src/main/java/org/springframework/web/reactive/resource/CssLinkResourceTransformer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * 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.
@@ -288,10 +288,9 @@ public class CssLinkResourceTransformer extends ResourceTransformerSupport {
 			if (this == other) {
 				return true;
 			}
-			if (!(other instanceof ContentChunkInfo)) {
+			if (!(other instanceof ContentChunkInfo otherCci)) {
 				return false;
 			}
-			ContentChunkInfo otherCci = (ContentChunkInfo) other;
 			return (this.start == otherCci.start && this.end == otherCci.end);
 		}
 

spring-webflux/src/main/java/org/springframework/web/reactive/resource/PathResourceResolver.java

@@ -42,6 +42,7 @@ import org.springframework.web.util.UriUtils;
  * expected to be configured at the end in a chain of resolvers.
  *
  * @author Rossen Stoyanchev
+ * @author Sam Brannen
  * @since 5.0
  */
 public class PathResourceResolver extends AbstractResourceResolver {
@@ -119,11 +120,12 @@ public class PathResourceResolver extends AbstractResourceResolver {
 					return Mono.just(resource);
 				}
 				else if (logger.isWarnEnabled()) {
-					Resource[] allowedLocations = getAllowedLocations();
-					logger.warn("Resource path \"" + resourcePath + "\" was successfully resolved " +
-							"but resource \"" + resource.getURL() + "\" is neither under the " +
-							"current location \"" + location.getURL() + "\" nor under any of the " +
-							"allowed locations " + (allowedLocations != null ? Arrays.asList(allowedLocations) : "[]"));
+					Object allowedLocationsText = (getAllowedLocations() != null ? Arrays.asList(getAllowedLocations()) : "[]");
+					logger.warn("""
+							Resource path "%s" was successfully resolved, but resource \
+							"%s" is neither under the current location "%s" nor under any \
+							of the allowed locations %s"\
+							""".formatted(resourcePath, resource.getURL(),location.getURL(), allowedLocationsText));
 				}
 			}
 			return Mono.empty();
@@ -177,8 +179,8 @@ public class PathResourceResolver extends AbstractResourceResolver {
 			resourcePath = resource.getURL().toExternalForm();
 			locationPath = StringUtils.cleanPath(location.getURL().toString());
 		}
-		else if (resource instanceof ClassPathResource) {
-			resourcePath = ((ClassPathResource) resource).getPath();
+		else if (resource instanceof ClassPathResource classPathResource) {
+			resourcePath = classPathResource.getPath();
 			locationPath = StringUtils.cleanPath(((ClassPathResource) location).getPath());
 		}
 		else {
@@ -203,10 +205,7 @@ public class PathResourceResolver extends AbstractResourceResolver {
 					return true;
 				}
 			}
-			catch (IllegalArgumentException ex) {
-				// May not be possible to decode...
-			}
-			catch (UnsupportedEncodingException ex) {
+			catch (IllegalArgumentException | UnsupportedEncodingException ex) {
 				// Should never happen...
 			}
 		}

spring-webflux/src/main/java/org/springframework/web/reactive/resource/ResourceUrlProvider.java

@@ -106,8 +106,7 @@ public class ResourceUrlProvider implements ApplicationListener<ContextRefreshed
 
 		mappings.forEach(mapping ->
 			mapping.getHandlerMap().forEach((pattern, handler) -> {
-				if (handler instanceof ResourceWebHandler) {
-					ResourceWebHandler resourceHandler = (ResourceWebHandler) handler;
+				if (handler instanceof ResourceWebHandler resourceHandler) {
 					this.handlerMap.put(pattern, resourceHandler);
 				}
 			}));

spring-webflux/src/main/java/org/springframework/web/reactive/resource/ResourceWebHandler.java

@@ -354,8 +354,7 @@ public class ResourceWebHandler implements WebHandler, InitializingBean {
 			return;
 		}
 		for (int i = getResourceResolvers().size() - 1; i >= 0; i--) {
-			if (getResourceResolvers().get(i) instanceof PathResourceResolver) {
-				PathResourceResolver resolver = (PathResourceResolver) getResourceResolvers().get(i);
+			if (getResourceResolvers().get(i) instanceof PathResourceResolver resolver) {
 				if (ObjectUtils.isEmpty(resolver.getAllowedLocations())) {
 					resolver.setAllowedLocations(getLocations().toArray(new Resource[0]));
 				}
@@ -522,10 +521,7 @@ public class ResourceWebHandler implements WebHandler, InitializingBean {
 					return true;
 				}
 			}
-			catch (IllegalArgumentException ex) {
-				// May not be possible to decode...
-			}
-			catch (UnsupportedEncodingException ex) {
+			catch (IllegalArgumentException | UnsupportedEncodingException ex) {
 				// Should never happen...
 			}
 		}
@@ -609,9 +605,8 @@ public class ResourceWebHandler implements WebHandler, InitializingBean {
 			headers.setContentType(mediaType);
 		}
 
-		if (resource instanceof HttpResource) {
-			HttpHeaders resourceHeaders = ((HttpResource) resource).getResponseHeaders();
-			exchange.getResponse().getHeaders().putAll(resourceHeaders);
+		if (resource instanceof HttpResource httpResource) {
+			exchange.getResponse().getHeaders().putAll(httpResource.getResponseHeaders());
 		}
 	}
 

spring-webflux/src/main/java/org/springframework/web/reactive/resource/VersionResourceResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * 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.
@@ -65,7 +65,7 @@ import org.springframework.web.server.ServerWebExchange;
  */
 public class VersionResourceResolver extends AbstractResourceResolver {
 
-	private AntPathMatcher pathMatcher = new AntPathMatcher();
+	private final AntPathMatcher pathMatcher = new AntPathMatcher();
 
 	/** Map from path pattern -> VersionStrategy. */
 	private final Map<String, VersionStrategy> versionStrategyMap = new LinkedHashMap<>();
@@ -315,8 +315,8 @@ public class VersionResourceResolver extends AbstractResourceResolver {
 
 		@Override
 		public HttpHeaders getResponseHeaders() {
-			HttpHeaders headers = (this.original instanceof HttpResource ?
-					((HttpResource) this.original).getResponseHeaders() : new HttpHeaders());
+			HttpHeaders headers = (this.original instanceof HttpResource httpResource ?
+					httpResource.getResponseHeaders() : new HttpHeaders());
 			headers.setETag("W/\"" + this.version + "\"");
 			return headers;
 		}

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/AbstractHandlerMethodMapping.java

@@ -200,8 +200,8 @@ public abstract class AbstractHandlerMethodMapping<T> extends AbstractHandlerMap
 	 * @param handler the bean name of a handler or a handler instance
 	 */
 	protected void detectHandlerMethods(final Object handler) {
-		Class<?> handlerType = (handler instanceof String ?
-				obtainApplicationContext().getType((String) handler) : handler.getClass());
+		Class<?> handlerType = (handler instanceof String beanName ?
+				obtainApplicationContext().getType(beanName) : handler.getClass());
 
 		if (handlerType != null) {
 			final Class<?> userType = ClassUtils.getUserClass(handlerType);
@@ -258,8 +258,8 @@ public abstract class AbstractHandlerMethodMapping<T> extends AbstractHandlerMap
 	 * @return the created HandlerMethod
 	 */
 	protected HandlerMethod createHandlerMethod(Object handler, Method method) {
-		if (handler instanceof String) {
-			return new HandlerMethod((String) handler,
+		if (handler instanceof String beanName) {
+			return new HandlerMethod(beanName,
 					obtainApplicationContext().getAutowireCapableBeanFactory(),
 					obtainApplicationContext(),
 					method);
@@ -397,14 +397,13 @@ public abstract class AbstractHandlerMethodMapping<T> extends AbstractHandlerMap
 	@Override
 	protected boolean hasCorsConfigurationSource(Object handler) {
 		return super.hasCorsConfigurationSource(handler) ||
-				(handler instanceof HandlerMethod && this.mappingRegistry.getCorsConfiguration((HandlerMethod) handler) != null);
+				(handler instanceof HandlerMethod handlerMethod && this.mappingRegistry.getCorsConfiguration(handlerMethod) != null);
 	}
 
 	@Override
 	protected CorsConfiguration getCorsConfiguration(Object handler, ServerWebExchange exchange) {
 		CorsConfiguration corsConfig = super.getCorsConfiguration(handler, exchange);
-		if (handler instanceof HandlerMethod) {
-			HandlerMethod handlerMethod = (HandlerMethod) handler;
+		if (handler instanceof HandlerMethod handlerMethod) {
 			if (handlerMethod.equals(PREFLIGHT_AMBIGUOUS_MATCH)) {
 				return ALLOW_CORS_CONFIG;
 			}

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/InvocableHandlerMethod.java

@@ -224,8 +224,7 @@ public class InvocableHandlerMethod extends HandlerMethod {
 				return true;
 			}
 			Type parameterType = returnType.getGenericParameterType();
-			if (parameterType instanceof ParameterizedType) {
-				ParameterizedType type = (ParameterizedType) parameterType;
+			if (parameterType instanceof ParameterizedType type) {
 				if (type.getActualTypeArguments().length == 1) {
 					return Void.class.equals(type.getActualTypeArguments()[0]);
 				}

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/RequestMappingInfo.java

@@ -343,10 +343,9 @@ public final class RequestMappingInfo implements RequestCondition<RequestMapping
 		if (this == other) {
 			return true;
 		}
-		if (!(other instanceof RequestMappingInfo)) {
+		if (!(other instanceof RequestMappingInfo otherInfo)) {
 			return false;
 		}
-		RequestMappingInfo otherInfo = (RequestMappingInfo) other;
 		return (this.patternsCondition.equals(otherInfo.patternsCondition) &&
 				this.methodsCondition.equals(otherInfo.methodsCondition) &&
 				this.paramsCondition.equals(otherInfo.paramsCondition) &&

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/RequestContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * 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.
@@ -72,7 +72,7 @@ public class RequestContext {
 	private Map<String, Errors> errorsMap;
 
 	@Nullable
-	private RequestDataValueProcessor dataValueProcessor;
+	private final RequestDataValueProcessor dataValueProcessor;
 
 
 	public RequestContext(ServerWebExchange exchange, Map<String, Object> model, MessageSource messageSource) {
@@ -92,8 +92,8 @@ public class RequestContext {
 		LocaleContext localeContext = exchange.getLocaleContext();
 		Locale locale = localeContext.getLocale();
 		this.locale = (locale != null ? locale : Locale.getDefault());
-		TimeZone timeZone = (localeContext instanceof TimeZoneAwareLocaleContext ?
-				((TimeZoneAwareLocaleContext) localeContext).getTimeZone() : null);
+		TimeZone timeZone = (localeContext instanceof TimeZoneAwareLocaleContext tzaLocaleContext ?
+				tzaLocaleContext.getTimeZone() : null);
 		this.timeZone = (timeZone != null ? timeZone : TimeZone.getDefault());
 
 		this.defaultHtmlEscape = null;  // TODO
@@ -385,15 +385,15 @@ public class RequestContext {
 			}
 		}
 
-		if (errors instanceof BindException) {
-			errors = ((BindException) errors).getBindingResult();
+		if (errors instanceof BindException bindException) {
+			errors = bindException.getBindingResult();
 		}
 
 		if (htmlEscape && !(errors instanceof EscapedErrors)) {
 			errors = new EscapedErrors(errors);
 		}
-		else if (!htmlEscape && errors instanceof EscapedErrors) {
-			errors = ((EscapedErrors) errors).getSource();
+		else if (!htmlEscape && errors instanceof EscapedErrors escapedErrors) {
+			errors = escapedErrors.getSource();
 		}
 
 		this.errorsMap.put(name, errors);

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/ViewResolverSupport.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * 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.
@@ -40,7 +40,7 @@ public abstract class ViewResolverSupport implements Ordered {
 	public static final MediaType DEFAULT_CONTENT_TYPE = MediaType.parseMediaType("text/html;charset=UTF-8");
 
 
-	private List<MediaType> mediaTypes = new ArrayList<>(4);
+	private final List<MediaType> mediaTypes = new ArrayList<>(4);
 
 	private Charset defaultCharset = StandardCharsets.UTF_8;
 

spring-webflux/src/main/java/org/springframework/web/reactive/socket/CloseStatus.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * 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.
@@ -239,10 +239,9 @@ public final class CloseStatus {
 		if (this == other) {
 			return true;
 		}
-		if (!(other instanceof CloseStatus)) {
+		if (!(other instanceof CloseStatus otherStatus)) {
 			return false;
 		}
-		CloseStatus otherStatus = (CloseStatus) other;
 		return (this.code == otherStatus.code &&
 				ObjectUtils.nullSafeEquals(this.reason, otherStatus.reason));
 	}

spring-webflux/src/main/java/org/springframework/web/reactive/socket/WebSocketMessage.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * 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.
@@ -151,10 +151,9 @@ public class WebSocketMessage {
 		if (this == other) {
 			return true;
 		}
-		if (!(other instanceof WebSocketMessage)) {
+		if (!(other instanceof WebSocketMessage otherMessage)) {
 			return false;
 		}
-		WebSocketMessage otherMessage = (WebSocketMessage) other;
 		return (this.type.equals(otherMessage.type) &&
 				ObjectUtils.nullSafeEquals(this.payload, otherMessage.payload));
 	}

spring-webflux/src/main/java/org/springframework/web/reactive/socket/adapter/StandardWebSocketHandlerAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * 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.
@@ -41,13 +41,14 @@ import org.springframework.web.reactive.socket.WebSocketSession;
  *
  * @author Violeta Georgieva
  * @author Rossen Stoyanchev
+ * @author Sam Brannen
  * @since 5.0
  */
 public class StandardWebSocketHandlerAdapter extends Endpoint {
 
 	private final WebSocketHandler delegateHandler;
 
-	private Function<Session, StandardWebSocketSession> sessionFactory;
+	private final Function<Session, StandardWebSocketSession> sessionFactory;
 
 	@Nullable
 	private StandardWebSocketSession delegateSession;
@@ -89,16 +90,16 @@ public class StandardWebSocketHandlerAdapter extends Endpoint {
 	private <T> WebSocketMessage toMessage(T message) {
 		WebSocketSession session = this.delegateSession;
 		Assert.state(session != null, "Cannot create message without a session");
-		if (message instanceof String) {
-			byte[] bytes = ((String) message).getBytes(StandardCharsets.UTF_8);
+		if (message instanceof String text) {
+			byte[] bytes = text.getBytes(StandardCharsets.UTF_8);
 			return new WebSocketMessage(Type.TEXT, session.bufferFactory().wrap(bytes));
 		}
-		else if (message instanceof ByteBuffer) {
-			DataBuffer buffer = session.bufferFactory().wrap((ByteBuffer) message);
+		else if (message instanceof ByteBuffer byteBuffer) {
+			DataBuffer buffer = session.bufferFactory().wrap(byteBuffer);
 			return new WebSocketMessage(Type.BINARY, buffer);
 		}
-		else if (message instanceof PongMessage) {
-			DataBuffer buffer = session.bufferFactory().wrap(((PongMessage) message).getApplicationData());
+		else if (message instanceof PongMessage pongMessage) {
+			DataBuffer buffer = session.bufferFactory().wrap(pongMessage.getApplicationData());
 			return new WebSocketMessage(Type.PONG, buffer);
 		}
 		else {