Apply "instanceof pattern matching" in spring-websocket

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

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

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

spring-websocket/src/main/java/org/springframework/web/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.
@@ -209,10 +209,9 @@ public final class CloseStatus implements Serializable {
 		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-websocket/src/main/java/org/springframework/web/socket/WebSocketHttpHeaders.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.
@@ -311,10 +311,9 @@ public class WebSocketHttpHeaders extends HttpHeaders {
 		if (this == other) {
 			return true;
 		}
-		if (!(other instanceof WebSocketHttpHeaders)) {
+		if (!(other instanceof WebSocketHttpHeaders otherHeaders)) {
 			return false;
 		}
-		WebSocketHttpHeaders otherHeaders = (WebSocketHttpHeaders) other;
 		return this.headers.equals(otherHeaders.headers);
 	}
 

spring-websocket/src/main/java/org/springframework/web/socket/client/WebSocketConnectionManager.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.
@@ -35,6 +35,7 @@ import org.springframework.web.socket.handler.LoggingWebSocketHandlerDecorator;
  * this will be done automatically when the Spring ApplicationContext is refreshed.
  *
  * @author Rossen Stoyanchev
+ * @author Sam Brannen
  * @since 4.0
  */
 public class WebSocketConnectionManager extends ConnectionManagerSupport {
@@ -46,7 +47,7 @@ public class WebSocketConnectionManager extends ConnectionManagerSupport {
 	@Nullable
 	private WebSocketSession webSocketSession;
 
-	private WebSocketHttpHeaders headers = new WebSocketHttpHeaders();
+	private final WebSocketHttpHeaders headers = new WebSocketHttpHeaders();
 
 
 	public WebSocketConnectionManager(WebSocketClient client,
@@ -116,16 +117,16 @@ public class WebSocketConnectionManager extends ConnectionManagerSupport {
 
 	@Override
 	public void startInternal() {
-		if (this.client instanceof Lifecycle && !((Lifecycle) this.client).isRunning()) {
-			((Lifecycle) this.client).start();
+		if (this.client instanceof Lifecycle lifecycle && !lifecycle.isRunning()) {
+			lifecycle.start();
 		}
 		super.startInternal();
 	}
 
 	@Override
 	public void stopInternal() throws Exception {
-		if (this.client instanceof Lifecycle && ((Lifecycle) this.client).isRunning()) {
-			((Lifecycle) this.client).stop();
+		if (this.client instanceof Lifecycle lifecycle && lifecycle.isRunning()) {
+			lifecycle.stop();
 		}
 		super.stopInternal();
 	}

spring-websocket/src/main/java/org/springframework/web/socket/messaging/DefaultSimpUserRegistry.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.
@@ -43,6 +43,7 @@ import org.springframework.util.Assert;
  * track of connected users and their subscriptions.
  *
  * @author Rossen Stoyanchev
+ * @author Sam Brannen
  * @since 4.2
  */
 public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicationListener {
@@ -105,8 +106,8 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 				return;
 			}
 			String name = user.getName();
-			if (user instanceof DestinationUserNameProvider) {
-				name = ((DestinationUserNameProvider) user).getDestinationUserName();
+			if (user instanceof DestinationUserNameProvider destinationUserNameProvider) {
+				name = destinationUserNameProvider.getDestinationUserName();
 			}
 			synchronized (this.sessionLock) {
 				LocalSimpUser simpUser = this.users.get(name);
@@ -238,7 +239,7 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 		@Override
 		public boolean equals(@Nullable Object other) {
 			return (this == other ||
-					(other instanceof SimpUser && getName().equals(((SimpUser) other).getName())));
+					(other instanceof SimpUser otherSimpUser && getName().equals(otherSimpUser.getName())));
 		}
 
 		@Override
@@ -294,7 +295,7 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 		@Override
 		public boolean equals(@Nullable Object other) {
 			return (this == other ||
-					(other instanceof SimpSubscription && getId().equals(((SimpSubscription) other).getId())));
+					(other instanceof SimpSubscription otherSubscription && getId().equals(otherSubscription.getId())));
 		}
 
 		@Override
@@ -346,10 +347,9 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 			if (this == other) {
 				return true;
 			}
-			if (!(other instanceof SimpSubscription)) {
+			if (!(other instanceof SimpSubscription otherSubscription)) {
 				return false;
 			}
-			SimpSubscription otherSubscription = (SimpSubscription) other;
 			return (getId().equals(otherSubscription.getId()) &&
 					getSession().getId().equals(otherSubscription.getSession().getId()));
 		}

spring-websocket/src/main/java/org/springframework/web/socket/server/support/HttpSessionHandshakeInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 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.
@@ -33,9 +33,9 @@ import org.springframework.web.socket.server.HandshakeInterceptor;
 
 /**
  * An interceptor to copy information from the HTTP session to the "handshake
- * attributes" map to made available via{@link WebSocketSession#getAttributes()}.
+ * attributes" map to be made available via {@link WebSocketSession#getAttributes()}.
  *
- * <p>Copies a subset or all HTTP session attributes and/or the HTTP session id
+ * <p>Copies a subset or all HTTP session attributes and/or the HTTP session ID
  * under the key {@link #HTTP_SESSION_ID_ATTR_NAME}.
  *
  * @author Rossen Stoyanchev
@@ -164,8 +164,7 @@ public class HttpSessionHandshakeInterceptor implements HandshakeInterceptor {
 
 	@Nullable
 	private HttpSession getSession(ServerHttpRequest request) {
-		if (request instanceof ServletServerHttpRequest) {
-			ServletServerHttpRequest serverRequest = (ServletServerHttpRequest) request;
+		if (request instanceof ServletServerHttpRequest serverRequest) {
 			return serverRequest.getServletRequest().getSession(isCreateSession());
 		}
 		return null;

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/DefaultTransportRequest.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.
@@ -59,7 +59,7 @@ class DefaultTransportRequest implements TransportRequest {
 
 	private final TransportType serverTransportType;
 
-	private SockJsMessageCodec codec;
+	private final SockJsMessageCodec codec;
 
 	@Nullable
 	private Principal user;

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/SockJsClient.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.
@@ -56,6 +56,7 @@ import org.springframework.web.util.UriComponentsBuilder;
  * the transports it is configured with.
  *
  * @author Rossen Stoyanchev
+ * @author Sam Brannen
  * @since 4.1
  * @see <a href="https://github.com/sockjs/sockjs-client">https://github.com/sockjs/sockjs-client</a>
  * @see org.springframework.web.socket.sockjs.client.Transport
@@ -114,8 +115,8 @@ public class SockJsClient implements WebSocketClient, Lifecycle {
 
 	private static InfoReceiver initInfoReceiver(List<Transport> transports) {
 		for (Transport transport : transports) {
-			if (transport instanceof InfoReceiver) {
-				return ((InfoReceiver) transport);
+			if (transport instanceof InfoReceiver infoReceiver) {
+				return infoReceiver;
 			}
 		}
 		return new RestTemplateXhrTransport();
@@ -202,11 +203,8 @@ public class SockJsClient implements WebSocketClient, Lifecycle {
 		if (!isRunning()) {
 			this.running = true;
 			for (Transport transport : this.transports) {
-				if (transport instanceof Lifecycle) {
-					Lifecycle lifecycle = (Lifecycle) transport;
-					if (!lifecycle.isRunning()) {
-						lifecycle.start();
-					}
+				if (transport instanceof Lifecycle lifecycle && !lifecycle.isRunning()) {
+					lifecycle.start();
 				}
 			}
 		}
@@ -217,11 +215,8 @@ public class SockJsClient implements WebSocketClient, Lifecycle {
 		if (isRunning()) {
 			this.running = false;
 			for (Transport transport : this.transports) {
-				if (transport instanceof Lifecycle) {
-					Lifecycle lifecycle = (Lifecycle) transport;
-					if (lifecycle.isRunning()) {
-						lifecycle.stop();
-					}
+				if (transport instanceof Lifecycle lifecycle && lifecycle.isRunning()) {
+					lifecycle.stop();
 				}
 			}
 		}

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/UndertowXhrTransport.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.
@@ -148,7 +148,7 @@ public class UndertowXhrTransport extends AbstractXhrTransport {
 			logger.trace("Starting XHR receive request for " + url);
 		}
 
-		ClientCallback<ClientConnection> clientCallback = new ClientCallback<ClientConnection>() {
+		ClientCallback<ClientConnection> clientCallback = new ClientCallback<>() {
 			@Override
 			public void completed(ClientConnection connection) {
 				ClientRequest request = new ClientRequest().setMethod(Methods.POST).setPath(url.getPath());
@@ -182,7 +182,7 @@ public class UndertowXhrTransport extends AbstractXhrTransport {
 			final URI url, final HttpHeaders headers, final XhrClientSockJsSession sockJsSession,
 			final SettableListenableFuture<WebSocketSession> connectFuture) {
 
-		return new ClientCallback<ClientExchange>() {
+		return new ClientCallback<>() {
 			@Override
 			public void completed(final ClientExchange exchange) {
 				exchange.setResponseListener(new ClientCallback<ClientExchange>() {
@@ -309,7 +309,7 @@ public class UndertowXhrTransport extends AbstractXhrTransport {
 	private ClientCallback<ClientExchange> createRequestCallback(final @Nullable String body,
 			final List<ClientResponse> responses, final CountDownLatch latch) {
 
-		return new ClientCallback<ClientExchange>() {
+		return new ClientCallback<>() {
 			@Override
 			public void completed(ClientExchange result) {
 				result.setResponseListener(new ClientCallback<ClientExchange>() {

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/XhrClientSockJsSession.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.
@@ -43,9 +43,9 @@ public class XhrClientSockJsSession extends AbstractClientSockJsSession {
 
 	private final XhrTransport transport;
 
-	private HttpHeaders headers;
+	private final HttpHeaders headers;
 
-	private HttpHeaders sendHeaders;
+	private final HttpHeaders sendHeaders;
 
 	private final URI sendUrl;
 

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/frame/SockJsFrame.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.
@@ -125,10 +125,9 @@ public class SockJsFrame {
 		if (this == other) {
 			return true;
 		}
-		if (!(other instanceof SockJsFrame)) {
+		if (!(other instanceof SockJsFrame otherFrame)) {
 			return false;
 		}
-		SockJsFrame otherFrame = (SockJsFrame) other;
 		return (this.type.equals(otherFrame.type) && this.content.equals(otherFrame.content));
 	}