71 lines
3.2 KiB
Java
71 lines
3.2 KiB
Java
package com.ankurm.ssews;
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import java.security.Principal;
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import java.time.Instant;
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import org.springframework.messaging.handler.annotation.MessageMapping;
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import org.springframework.messaging.handler.annotation.Payload;
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import org.springframework.messaging.handler.annotation.SendTo;
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import org.springframework.messaging.simp.SimpMessageHeaderAccessor;
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import org.springframework.messaging.simp.SimpMessageType;
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import org.springframework.messaging.simp.SimpMessagingTemplate;
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import org.springframework.stereotype.Controller;
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/**
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* The chat. Three handlers, each demonstrating a different routing rule.
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*
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* @see <a href="../../../../../docs/04-stomp.md">docs/04-stomp.md</a>
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*/
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@Controller
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public class ChatController {
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private final SimpMessagingTemplate template;
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ChatController(SimpMessagingTemplate template) {
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this.template = template;
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}
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/** Explicit fan-out destination. Client SENDs to /app/chat.send, subscribers get /topic/room. */
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@MessageMapping("/chat.send")
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@SendTo("/topic/room")
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public ChatMessage send(@Payload ChatMessage in, SimpMessageHeaderAccessor headers) {
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String from = in.from() == null ? headers.getSessionId() : in.from();
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return new ChatMessage(from, in.text(), Instant.now());
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}
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/**
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* No {@code @SendTo}. The return value still goes somewhere: the default destination is the
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* broker prefix plus the mapping, i.e. {@code /topic/chat.echo}. That default is why a
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* handler you thought was private is readable by anyone who guesses the path.
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*/
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@MessageMapping("/chat.echo")
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public ChatMessage echo(@Payload ChatMessage in) {
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return new ChatMessage("echo", in.text(), Instant.now());
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}
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/**
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* Point-to-point. Sent to one session's private destination; every other subscriber to
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* /user/queue/whisper gets nothing, because the broker rewrote the destination per session.
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*
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* <p>The three extra lines are not optional and their absence is silent. With no
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* authenticated {@link Principal} the "user" is the STOMP session id, and
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* {@code DefaultUserDestinationResolver} can only turn a session id into a real destination
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* if the message also <em>carries</em> that session id in its headers. Call the two-argument
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* {@code convertAndSendToUser(sessionId, dest, payload)} instead and the message is resolved
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* against a user registry that has never heard of that name: no exception, no log line, no
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* delivery. {@code setLeaveMutable(true)} is required too — without it the accessor is
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* immutable by the time the resolver looks, and the session id is lost again.
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*/
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@MessageMapping("/chat.whisper")
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public void whisper(@Payload ChatMessage in, SimpMessageHeaderAccessor headers, Principal principal) {
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String targetSessionId = in.from();
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SimpMessageHeaderAccessor out = SimpMessageHeaderAccessor.create(SimpMessageType.MESSAGE);
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out.setSessionId(targetSessionId);
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out.setLeaveMutable(true);
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template.convertAndSendToUser(targetSessionId, "/queue/whisper",
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new ChatMessage(principal == null ? headers.getSessionId() : principal.getName(),
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in.text(), Instant.now()),
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out.getMessageHeaders());
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}
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}
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