spring 如何使用Spring通过websocket向客户端发送消息
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How to send message to client through websocket using Spring
提问by cheb1k4
I try to use Spring with websocket. I started my investigation with this tutorial.
我尝试将 Spring 与 websocket 一起使用。我从本教程开始我的调查。
In my side client I have something like that to initialize the connection to the server :
在我的侧面客户端中，我有类似的东西来初始化与服务器的连接：
function connect() {
var socket = new SockJS('/myphotos/form');
stompClient = Stomp.over(socket);
stompClient.connect({}, function(frame) {
setConnected(true);
console.log('Connected: ' + frame);
stompClient.subscribe('/topic/greetings', function(greeting){
showGreeting(JSON.parse(greeting.body).content);
});
});
}
It works great, in my controller I'm able to do my process in the following class :
它工作得很好，在我的控制器中，我可以在以下课程中完成我的过程：
@Controller
@RequestMapping("/")
public class PhotoController {
@MessageMapping("/form")
@SendTo("/topic/greetings")
public Greeting validate(AddPhotosForm addPhotosForm) {
return new Greeting("Hello world !");
}
}
Now what I want to do it's having a thread sending a message to the client listening on “/topic/greeting”. I wrote my Runnable class like this :
现在我想做的是让一个线程向客户端发送一条消息，监听“/topic/greeting”。我这样写了我的 Runnable 类：
public class FireGreeting implements Runnable {
private PhotoController listener;
public FireGreeting(PhotoController listener) {
this.listener = listener;
}
@Override
public void run() {
while (true) {
try {
Thread.sleep( 2000 );
listener.fireGreeting();
} catch ( InterruptedException e ) {
e.printStackTrace();
}
}
}
}
And completed my controller like that :
并像这样完成了我的控制器：
@Controller
@RequestMapping("/")
public class PhotoController {
@MessageMapping("/form")
@SendTo("/topic/greetings")
public Greeting validate(AddPhotosForm addPhotosForm) {
// added this part
FireGreeting r = new FireGreeting( this );
new Thread(r).start();
return new Greeting("Hello world !");
}
// added this method
@SendTo("/topic/greetings")
public Greeting fireGreeting() {
System.out.println("Fire");
return new Greeting("Fire");
}
}
The method PhotoController.fireGreeting is called as I want but nothing happened on the client side. Any suggestions ? Thank you.
PhotoController.fireGreeting 方法按照我的意愿被调用，但在客户端什么也没发生。有什么建议 ？谢谢你。
回答by cheb1k4
I was able to solve my problem thanks to @Boris the Spider. The correct solution is to do something like that :
感谢@Boris the Spider，我能够解决我的问题。正确的解决方案是做这样的事情：
@Controller
@RequestMapping("/")
public class PhotoController {
@Autowired
private SimpMessagingTemplate template;
@MessageMapping("/form")
@SendTo("/topic/greetings")
public Greeting validate(AddPhotosForm addPhotosForm) {
FireGreeting r = new FireGreeting( this );
new Thread(r).start();
return new Greeting("Hello world !");
}
public void fireGreeting() {
System.out.println("Fire");
this.template.convertAndSend("/topic/greetings", new Greeting("Fire"));
}
}
回答by mfilippo
A better way to schedule periodic tasks is, as suggested by @Boris the Spider, to use Spring scheduling mechanisms (see this guide).
正如@Boris the Spider 所建议的那样，调度周期性任务的更好方法是使用 Spring 调度机制（请参阅本指南）。
For the sake of Separation of Concerns, I would also separate scheduled-related code from controller code.
为了关注点分离，我还将与调度相关的代码与控制器代码分开。
In your case you could use a class like this one:
在您的情况下，您可以使用这样的类：
@Component
public class ScheduledTasks {
@Autowired
private SimpMessagingTemplate template;
@Scheduled(fixedRate = 2000)
public void fireGreeting() {
this.template.convertAndSend("/topic/greetings", new Greeting("Fire"));
}
}
And add the @EnableSchedulingtag to your Application class.
并将@EnableScheduling标签添加到您的应用程序类。
