Spring Web Socket - send to user (#4135)

spring-mvc-java/pom.xml

@@ -148,6 +148,13 @@
             <artifactId>javax.el</artifactId>
             <version>2.2.4</version>
         </dependency>
+
+        <!-- Web socket to user example -->
+
+        <dependency>
+            <groupId>com.google.code.gson</groupId>
+            <artifactId>gson</artifactId>
+        </dependency>
     </dependencies>
 
     <build>

spring-mvc-java/src/main/java/com/baeldung/spring/web/config/WebSocketSendToUserConfig.java

@@ -0,0 +1,42 @@
+package com.baeldung.spring.web.config;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.http.server.ServerHttpRequest;
+import org.springframework.http.server.ServerHttpResponse;
+import org.springframework.http.server.ServletServerHttpRequest;
+import org.springframework.messaging.simp.config.MessageBrokerRegistry;
+import org.springframework.web.socket.WebSocketHandler;
+import org.springframework.web.socket.config.annotation.AbstractWebSocketMessageBrokerConfigurer;
+import org.springframework.web.socket.config.annotation.EnableWebSocketMessageBroker;
+import org.springframework.web.socket.config.annotation.StompEndpointRegistry;
+import org.springframework.web.socket.server.support.DefaultHandshakeHandler;
+
+import javax.servlet.http.HttpSession;
+import java.util.Map;
+
+@Configuration
+@EnableWebSocketMessageBroker
+public class WebSocketSendToUserConfig extends AbstractWebSocketMessageBrokerConfigurer {
+
+    @Override
+    public void configureMessageBroker(MessageBrokerRegistry config) {
+        config.enableSimpleBroker("/topic/", "/queue/");
+        config.setApplicationDestinationPrefixes("/app");
+    }
+
+    @Override
+    public void registerStompEndpoints(StompEndpointRegistry registry) {
+        registry.addEndpoint("/greeting").setHandshakeHandler(new DefaultHandshakeHandler() {
+
+            //Get sessionId from request and set it in Map attributes
+            public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler,
+                                             Map attributes) throws Exception {
+                if (request instanceof ServletServerHttpRequest) {
+                    ServletServerHttpRequest servletRequest = (ServletServerHttpRequest) request;
+                    HttpSession session = servletRequest.getServletRequest().getSession();
+                    attributes.put("sessionId", session.getId());
+                }
+                return true;
+            }}).withSockJS();
+    }
+}

spring-mvc-java/src/main/java/com/baeldung/web/controller/WebsocketSendToUserController.java

@@ -0,0 +1,34 @@
+package com.baeldung.web.controller;
+
+import com.google.gson.Gson;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.messaging.handler.annotation.MessageExceptionHandler;
+import org.springframework.messaging.handler.annotation.MessageMapping;
+import org.springframework.messaging.handler.annotation.Payload;
+import org.springframework.messaging.simp.SimpMessageSendingOperations;
+import org.springframework.messaging.simp.annotation.SendToUser;
+import org.springframework.stereotype.Controller;
+
+import java.security.Principal;
+import java.util.Map;
+
+@Controller
+public class WebsocketSendToUserController {
+
+    @Autowired
+    private SimpMessageSendingOperations messagingTemplate;
+
+    private Gson gson = new Gson();
+
+    @MessageMapping("/message")
+    @SendToUser("/queue/reply")
+    public String processMessageFromClient(@Payload String message, Principal principal) throws Exception {
+        return gson.fromJson(message, Map.class).get("name").toString();
+    }
+
+    @MessageExceptionHandler
+    @SendToUser("/queue/errors")
+    public String handleException(Throwable exception) {
+        return exception.getMessage();
+    }
+}

spring-mvc-java/src/main/webapp/resources/js/webSocketSendToUserApp.js

@@ -0,0 +1,24 @@
+function connect() {
+    var socket = new WebSocket('ws://localhost:8080/greeting');
+    ws = Stomp.over(socket);
+
+    ws.connect({}, function(frame) {
+        ws.subscribe("/user/queue/errors", function(message) {
+            alert("Error " + message.body);
+        });
+
+        ws.subscribe("/user/queue/reply", function(message) {
+            alert("Message " + message.body);
+        });
+    }, function(error) {
+        alert("STOMP error " + error);
+    });
+}
+
+function disconnect() {
+    if (ws != null) {
+        ws.close();
+    }
+    setConnected(false);
+    console.log("Disconnected");
+}