Backend-Code clean-up and modernization for Java 11 (#1692)

- Clean-up code using Eclipse IDE
- Apply checkstyle
- Use Java 11 features - mainly the `var` keyword, where appropriate

cnf/checkstyle.xml

@@ -108,7 +108,7 @@
       <message key="name.invalidPattern" value="Parameter name ''{0}'' must match pattern ''{1}''."/>
     </module>
     <module name="LambdaParameterName">
-      <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
+      <property name="format" value="^[a-z][a-zA-Z0-9]*?$"/>
       <message key="name.invalidPattern" value="Lambda parameter name ''{0}'' must match pattern ''{1}''."/>
     </module>
     <module name="CatchParameterName">

io.openems.backend.application/src/io/openems/backend/application/BackendApp.java

@@ -1,7 +1,6 @@
 package io.openems.backend.application;
 
 import java.io.IOException;
-import java.util.Dictionary;
 import java.util.Hashtable;
 
 import org.osgi.service.cm.Configuration;
@@ -23,22 +22,22 @@ public class BackendApp {
 	private final Logger log = LoggerFactory.getLogger(BackendApp.class);
 
 	@Reference
-	ConfigurationAdmin cm;
+	private ConfigurationAdmin cm;
 
 	@Activate
-	void activate() {
-		String message = "OpenEMS Backend version [" + OpenemsConstants.VERSION + "] started";
-		String line = Strings.repeat("=", message.length());
-		log.info(line);
-		log.info(message);
-		log.info(line);
+	private void activate() {
+		final var message = "OpenEMS Backend version [" + OpenemsConstants.VERSION + "] started";
+		final var line = Strings.repeat("=", message.length());
+		this.log.info(line);
+		this.log.info(message);
+		this.log.info(line);
 
 		Configuration config;
 		try {
-			config = cm.getConfiguration("org.ops4j.pax.logging", null);
-			Dictionary<String, Object> properties = config.getProperties();
+			config = this.cm.getConfiguration("org.ops4j.pax.logging", null);
+			final var properties = config.getProperties();
 			if (properties == null || properties.isEmpty() || properties.get("log4j2.rootLogger.level") == null) {
-				Hashtable<String, Object> log4j = new Hashtable<>();
+				final var log4j = new Hashtable<String, Object>();
 				log4j.put("log4j2.appender.console.type", "Console");
 				log4j.put("log4j2.appender.console.name", "console");
 				log4j.put("log4j2.appender.console.layout.type", "PatternLayout");
@@ -58,8 +57,8 @@ void activate() {
 	}
 
 	@Deactivate
-	void deactivate() {
-		log.info("Deactivate BackendApp");
+	private void deactivate() {
+		this.log.info("Deactivate BackendApp");
 	}
 
 }

io.openems.backend.b2brest/src/io/openems/backend/b2brest/B2bRest.java

@@ -42,18 +42,18 @@ public B2bRest() {
 	}
 
 	@Activate
-	void activate(Config config) throws OpenemsException {
+	private void activate(Config config) throws OpenemsException {
 		this.startServer(config.port());
 	}
 
 	@Deactivate
-	void deactivate() {
+	private void deactivate() {
 		this.stopServer();
 	}
 
 	/**
 	 * Create and start new server.
-	 * 
+	 *
 	 * @param port the port
 	 * @throws OpenemsException on error
 	 */

io.openems.backend.b2brest/src/io/openems/backend/b2brest/RestHandler.java

@@ -72,15 +72,15 @@ public void handle(String target, Request baseRequest, HttpServletRequest reques
 
 	/**
 	 * Authenticate a user.
-	 * 
+	 *
 	 * @param request the HttpServletRequest
 	 * @return the {@link User}
 	 * @throws OpenemsNamedException on error
 	 */
 	private User authenticate(HttpServletRequest request) throws OpenemsNamedException {
 		String authHeader = request.getHeader("Authorization");
 		if (authHeader != null) {
-			StringTokenizer st = new StringTokenizer(authHeader);
+			var st = new StringTokenizer(authHeader);
 			if (st.hasMoreTokens()) {
 				String basic = st.nextToken();
 				if (basic.equalsIgnoreCase("Basic")) {
@@ -92,8 +92,8 @@ private User authenticate(HttpServletRequest request) throws OpenemsNamedExcepti
 					}
 					int p = credentials.indexOf(":");
 					if (p != -1) {
-						String username = credentials.substring(0, p).trim();
-						String password = credentials.substring(p + 1).trim();
+						var username = credentials.substring(0, p).trim();
+						var password = credentials.substring(p + 1).trim();
 						// authenticate using username & password
 						return this.parent.metadata.authenticate(username, password);
 					}
@@ -140,7 +140,7 @@ private void sendErrorResponse(Request baseRequest, HttpServletResponse response
 
 	/**
 	 * Parses a Request to JSON.
-	 * 
+	 *
 	 * @param baseRequest the Request
 	 * @return the {@link JsonObject}
 	 * @throws OpenemsException on error
@@ -159,15 +159,15 @@ private static JsonObject parseJson(Request baseRequest) throws OpenemsException
 
 	/**
 	 * Handles an http request to 'jsonrpc' endpoint.
-	 * 
+	 *
 	 * @param user         the {@link User}
 	 * @param baseRequest  the {@link Request}
 	 * @param httpRequest  the {@link HttpServletRequest}
 	 * @param httpResponse the {@link HttpServletResponse}
 	 */
 	private void handleJsonRpc(User user, Request baseRequest, HttpServletRequest httpRequest,
 			HttpServletResponse httpResponse) {
-		UUID requestId = new UUID(0L, 0L); /* dummy UUID */
+		var requestId = new UUID(0L, 0L); /* dummy UUID */
 		try {
 			// call handler methods
 			if (!httpRequest.getMethod().equals("POST")) {
@@ -176,17 +176,17 @@ private void handleJsonRpc(User user, Request baseRequest, HttpServletRequest ht
 			}
 
 			// parse json and add "jsonrpc" and "id" properties if missing
-			JsonObject json = RestHandler.parseJson(baseRequest);
+			var json = RestHandler.parseJson(baseRequest);
 			if (!json.has("jsonrpc")) {
 				json.addProperty("jsonrpc", "2.0");
 			}
 			if (!json.has("id")) {
 				json.addProperty("id", UUID.randomUUID().toString());
 			}
 			if (json.has("params")) {
-				JsonObject params = JsonUtils.getAsJsonObject(json, "params");
+				var params = JsonUtils.getAsJsonObject(json, "params");
 				if (params.has("payload")) {
-					JsonObject payload = JsonUtils.getAsJsonObject(params, "payload");
+					var payload = JsonUtils.getAsJsonObject(params, "payload");
 					if (!payload.has("jsonrpc")) {
 						payload.addProperty("jsonrpc", "2.0");
 					}
@@ -198,11 +198,11 @@ private void handleJsonRpc(User user, Request baseRequest, HttpServletRequest ht
 				json.add("params", params);
 			}
 			// parse JSON-RPC Request
-			JsonrpcMessage message = JsonrpcMessage.from(json);
+			var message = JsonrpcMessage.from(json);
 			if (!(message instanceof JsonrpcRequest)) {
 				throw new OpenemsException("Only JSON-RPC Request is supported here.");
 			}
-			JsonrpcRequest request = (JsonrpcRequest) message;
+			var request = (JsonrpcRequest) message;
 
 			// handle the request
 			CompletableFuture<? extends JsonrpcResponseSuccess> responseFuture = this.parent.jsonRpcRequestHandler

io.openems.backend.b2bwebsocket/src/io/openems/backend/b2bwebsocket/B2bWebsocket.java

@@ -52,25 +52,25 @@ public B2bWebsocket() {
 	private Config config;
 
 	private final Runnable startServerWhenMetadataIsInitialized = () -> {
-		this.startServer(config.port(), config.poolSize(), config.debugMode());
+		this.startServer(this.config.port(), this.config.poolSize(), this.config.debugMode());
 	};
 
 	@Activate
-	void activate(Config config) {
+	private void activate(Config config) {
 		this.config = config;
 		this.metadata.addOnIsInitializedListener(this.startServerWhenMetadataIsInitialized);
 	}
 
 	@Deactivate
-	void deactivate() {
+	private void deactivate() {
 		ThreadPoolUtils.shutdownAndAwaitTermination(this.executor, 5);
 		this.metadata.removeOnIsInitializedListener(this.startServerWhenMetadataIsInitialized);
 		this.stopServer();
 	}
 
 	/**
 	 * Create and start new server.
-	 * 
+	 *
 	 * @param port      the port
 	 * @param poolSize  number of threads dedicated to handle the tasks
 	 * @param debugMode activate a regular debug log about the state of the tasks

io.openems.backend.b2bwebsocket/src/io/openems/backend/b2bwebsocket/OnClose.java

@@ -1,12 +1,9 @@
 package io.openems.backend.b2bwebsocket;
 
-import java.util.Optional;
-
 import org.java_websocket.WebSocket;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import io.openems.backend.common.metadata.User;
 import io.openems.common.exceptions.OpenemsException;
 
 public class OnClose implements io.openems.common.websocket.OnClose {
@@ -21,7 +18,7 @@ public OnClose(B2bWebsocket parent) {
 	@Override
 	public void run(WebSocket ws, int code, String reason, boolean remote) throws OpenemsException {
 		WsData wsData = ws.getAttachment();
-		Optional<User> user = wsData.getUserOpt();
+		var user = wsData.getUserOpt();
 		if (user.isPresent()) {
 			this.parent.logInfo(this.log, "User [" + user.get().getName() + "] closed connection");
 		} else {

io.openems.backend.b2bwebsocket/src/io/openems/backend/b2bwebsocket/OnOpen.java

@@ -28,21 +28,21 @@ public void run(WebSocket ws, JsonObject handshake) throws OpenemsNamedException
 		try {
 			// Read "Authorization" header for Simple HTTP authentication. Source:
 			// https://stackoverflow.com/questions/16000517/how-to-get-password-from-http-basic-authentication
-			final String authorization = JsonUtils.getAsString(handshake, "Authorization");
+			final var authorization = JsonUtils.getAsString(handshake, "Authorization");
 			if (authorization == null || !authorization.toLowerCase().startsWith("basic")) {
 				throw OpenemsError.COMMON_AUTHENTICATION_FAILED.exception();
 			}
 
 			String base64Credentials = authorization.substring("Basic".length()).trim();
 			byte[] credDecoded = Base64.getDecoder().decode(base64Credentials);
-			String credentials = new String(credDecoded, StandardCharsets.UTF_8);
+			var credentials = new String(credDecoded, StandardCharsets.UTF_8);
 			// credentials = username:password
-			final String[] values = credentials.split(":", 2);
+			final var values = credentials.split(":", 2);
 			if (values.length != 2) {
 				throw OpenemsError.COMMON_AUTHENTICATION_FAILED.exception();
 			}
-			String username = values[0];
-			String password = values[1];
+			var username = values[0];
+			var password = values[1];
 			User user = this.parent.metadata.authenticate(username, password);
 
 			WsData wsData = ws.getAttachment();

io.openems.backend.b2bwebsocket/src/io/openems/backend/b2bwebsocket/OnRequest.java

@@ -27,7 +27,7 @@ public OnRequest(B2bWebsocket parent) {
 	public CompletableFuture<? extends JsonrpcResponseSuccess> run(WebSocket ws, JsonrpcRequest request)
 			throws OpenemsException, OpenemsNamedException {
 		WsData wsData = ws.getAttachment();
-		User user = wsData.getUserWithTimeout(5, TimeUnit.SECONDS);
+		var user = wsData.getUserWithTimeout(5, TimeUnit.SECONDS);
 
 		switch (request.getMethod()) {
 
@@ -42,7 +42,7 @@ public CompletableFuture<? extends JsonrpcResponseSuccess> run(WebSocket ws, Jso
 
 	/**
 	 * Handles a {@link SubscribeEdgesChannelsRequest}.
-	 * 
+	 *
 	 * @param wsData    the WebSocket attachment
 	 * @param user      the {@link User}
 	 * @param messageId the JSON-RPC Message-ID
@@ -58,7 +58,7 @@ private CompletableFuture<GenericJsonrpcResponseSuccess> handleSubscribeEdgesCha
 		}
 
 		// activate SubscribedChannelsWorker
-		SubscribedEdgesChannelsWorker worker = wsData.getSubscribedChannelsWorker();
+		var worker = wsData.getSubscribedChannelsWorker();
 		worker.handleSubscribeEdgesChannelsRequest(request);
 
 		// JSON-RPC response

io.openems.backend.b2bwebsocket/src/io/openems/backend/b2bwebsocket/SubscribedEdgesChannelsWorker.java

@@ -6,7 +6,6 @@
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 
-import org.java_websocket.WebSocket;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -15,7 +14,6 @@
 
 import io.openems.backend.b2bwebsocket.jsonrpc.notification.EdgesCurrentDataNotification;
 import io.openems.backend.b2bwebsocket.jsonrpc.request.SubscribeEdgesChannelsRequest;
-import io.openems.backend.common.metadata.User;
 import io.openems.common.exceptions.OpenemsError.OpenemsNamedException;
 import io.openems.common.session.Role;
 import io.openems.common.types.ChannelAddress;
@@ -54,7 +52,7 @@ public SubscribedEdgesChannelsWorker(B2bWebsocket parent, WsData wsData) {
 
 	/**
 	 * Applies a SubscribeChannelsRequest.
-	 * 
+	 *
 	 * @param request the SubscribeEdgesChannelsRequest
 	 */
 	public synchronized void handleSubscribeEdgesChannelsRequest(SubscribeEdgesChannelsRequest request) {
@@ -66,7 +64,7 @@ public synchronized void handleSubscribeEdgesChannelsRequest(SubscribeEdgesChann
 
 	/**
 	 * Updates the Subscription data.
-	 * 
+	 *
 	 * @param edgeIds  Set of Edge-IDs
 	 * @param channels Set of ChannelAddresses
 	 */
@@ -91,7 +89,7 @@ private synchronized void updateSubscription(Set<String> edgeIds, Set<ChannelAdd
 				/*
 				 * This task is executed regularly. Sends data to Websocket.
 				 */
-				WebSocket ws = this.wsData.getWebsocket();
+				var ws = this.wsData.getWebsocket();
 				if (ws == null || !ws.isOpen()) {
 					// disconnected; stop worker
 					this.dispose();
@@ -104,14 +102,17 @@ private synchronized void updateSubscription(Set<String> edgeIds, Set<ChannelAdd
 					this.log.warn("Unable to send SubscribedChannels: " + e.getMessage());
 				}
 
-			}, 0, UPDATE_INTERVAL_IN_SECONDS, TimeUnit.SECONDS));
+			}, 0, SubscribedEdgesChannelsWorker.UPDATE_INTERVAL_IN_SECONDS, TimeUnit.SECONDS));
 		}
 	}
 
+	/**
+	 * Dispose and deactivate this worker.
+	 */
 	public void dispose() {
 		// unsubscribe regular task
 		if (this.futureOpt.isPresent()) {
-			futureOpt.get().cancel(true);
+			this.futureOpt.get().cancel(true);
 		}
 	}
 
@@ -122,8 +123,8 @@ public void dispose() {
 	 * @throws OpenemsNamedException on error
 	 */
 	private EdgesCurrentDataNotification getCurrentDataNotification() throws OpenemsNamedException {
-		EdgesCurrentDataNotification result = new EdgesCurrentDataNotification();
-		User user = this.wsData.getUserWithTimeout(5, TimeUnit.SECONDS);
+		var result = new EdgesCurrentDataNotification();
+		var user = this.wsData.getUserWithTimeout(5, TimeUnit.SECONDS);
 
 		for (String edgeId : this.edgeIds) {
 			// assure read permissions of this User for this Edge.

io.openems.backend.b2bwebsocket/src/io/openems/backend/b2bwebsocket/WebsocketServer.java

@@ -40,7 +40,7 @@ protected OnRequest getOnRequest() {
 
 	@Override
 	public OnNotification getOnNotification() {
-		return onNotification;
+		return this.onNotification;
 	}
 
 	@Override