While Sending data over spring webscoket getting NUllpointerException - nullpointerexception

Question

From last 2 days, I am facing this issue. After debugging, I can see that spring websocket sending data to queue but not received by client
I am not getting any error but sometime i got this error.
Exception in thread "clientInboundChannel-23"
org.springframework.messaging.MessageDeliveryException: Failed to send
message to ExecutorSubscribableChannel[clientOutboundChannel]; nested
exception is java.lang.NullPointerException,
failedMessage=GenericMessage [payload=byte[0],
headers={simpMessageType=DISCONNECT_ACK,
simpDisconnectMessage=GenericMessage [payload=byte[0],
headers={simpMessageType=DISCONNECT, stompCommand=DISCONNECT,
simpSessionAttributes={org.springframework.messaging.simp.SimpAttributes.COMPLETED=true},
simpUser=com.gn.beans.User#44880668, simpSessionId=egw2xot3}],
simpUser=com.gn.beans.User#44880668, simpSessionId=egw2xot3}] at
org.springframework.messaging.support.AbstractMessageChannel.send(AbstractMessageChannel.java:127)
at
org.springframework.messaging.support.AbstractMessageChannel.send(AbstractMessageChannel.java:104)
at
org.springframework.messaging.simp.broker.SimpleBrokerMessageHandler.handleDisconnect(SimpleBrokerMessageHandler.java:328)
at
org.springframework.messaging.simp.broker.SimpleBrokerMessageHandler.handleMessageInternal(SimpleBrokerMessageHandler.java:282)
at
org.springframework.messaging.simp.broker.AbstractBrokerMessageHandler.handleMessage(AbstractBrokerMessageHandler.java:238)
at
org.springframework.messaging.support.ExecutorSubscribableChannel$SendTask.run(ExecutorSubscribableChannel.java:135)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source) Caused by:
java.lang.NullPointerException at
com.gn.interceptors.WebSocketInterceptor.preSend(WebSocketInterceptor.java:24)
at
org.springframework.messaging.support.AbstractMessageChannel$ChannelInterceptorChain.applyPreSend(AbstractMessageChannel.java:158)
at
org.springframework.messaging.support.AbstractMessageChannel.send(AbstractMessageChannel.java:113)
... 8 more
My websocket setup is shown below.
WebSocketConfig.java
package com.gn.config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.messaging.simp.config.ChannelRegistration;
import org.springframework.messaging.simp.config.MessageBrokerRegistry;
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.config.annotation.WebSocketTransportRegistration;
import com.gn.interceptors.WebSocketInterceptor;
#Configuration
#EnableWebSocketMessageBroker
public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {
#Override
public void configureMessageBroker(MessageBrokerRegistry config) {
config.enableSimpleBroker("/advantageClient","/advantageAll");
config.setApplicationDestinationPrefixes("/app");
}
#Override
public void registerStompEndpoints(StompEndpointRegistry registry) {
registry.addEndpoint("/websocket").setAllowedOrigins("*");
registry.addEndpoint("/websocket").setAllowedOrigins("*").withSockJS();
}
#Bean
public WebSocketInterceptor webSocketInterceptor() {
return new WebSocketInterceptor();
}
#Override
public void configureClientInboundChannel(ChannelRegistration registration) {
registration.setInterceptors(webSocketInterceptor());
}
#Override
public void configureClientOutboundChannel(ChannelRegistration registration) {
registration.taskExecutor().corePoolSize(8);
registration.setInterceptors(webSocketInterceptor());
}
#Override
public void configureWebSocketTransport(WebSocketTransportRegistration registration)
{
registration.setSendTimeLimit(15 * 1000)
.setSendBufferSizeLimit(200 * 1024 * 1024)
.setMessageSizeLimit(200 * 1024 * 1024);
}
}
WebSocketUtils.java to send data to client
import java.util.HashMap;
import java.util.Map;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.messaging.simp.SimpMessagingTemplate;
public class WebSocketUtil {
private static final Logger logger = LoggerFactory.getLogger("com.gn.utils");
private static SimpMessagingTemplate template;
public static void setTemplate(SimpMessagingTemplate tmplt) {
template = tmplt;
}
public static void sendToUser(String message,int userId) {
logger.info("Send to user with userID id "+userId+" msg is "+message);
String uId = String.valueOf(userId);
template.convertAndSendToUser(uId,"/advantageClient/connect/", message);
// template.convertAndSendToUser(userId+"","/advantageClient/connect/", message);
}
public static void sendToAll(String message) {
logger.info("Send to all with msg is "+message);
template.convertAndSend("/advantageAll/connect/", message);
}
}
Client Code to connect Websocket
connect() {
const uId = this.homeService.getUserId();
let ws = new SockJS(environment.apiProtocol + '://' + environment.apiHost + ':' + environment.apiPort + UrlConstantsService.urlConstants.advantageService + UrlConstantsService.urlConstants.websocket);
this.ws = Stomp.over(ws);
let that = this;
this.ws.connect({userId: uId}, function(frame) {
that.ws.subscribe('/user/advantageClient/connect/', function(msg) {
that.change.emit(JSON.parse(msg.body));
});
that.ws.subscribe('/advantageAll/connect/', function(msg) {
that.change.emit(JSON.parse(msg.body));
});
}, function(error) {
console.log('error connecting to server', error);
});
}
disconnect() {
if (this.ws !== null) {
this.ws.ws.close();
}
}