Spring Boot WebSocket And Android Client

Spring Boot WebSocket Server, with a browser client and a simple Android client. Android client uses StompProtocolAndroid which implements ptotocol STOMP on Android, to subscribe or send message to server.

Introduction

中文

Server now include three endpoints to receive message from client:

/broadcast

This endpoint will simply transfer all messages it received to subscriber of /b.

/group/{groupID}

This endpoint is used to dynamicly create groups. For example, client can send a message to /group/1, and all subscriber of /g/1 will receive the message. Also, you can change the subscribe endpoint by changing the Controller and WebSocketConfig

/chat

Endpoint /chat is used to enable point-to-point communication. If Alice(with userID 1) want to chat with Bob(with userID 2), she should send a message to endpoint /chat with a special json object defined as ChatMessage:

// js code
function sendMessage() {
    var message = $('#message').val();
    stompClient.send('/chat', {}, JSON.stringify({
        'userID': 2, 
        'fromUserID': 1, 
        'message': "Hello Bob"})
    );
}

userID is necessary, this field will be used in server code to transfer message:

simpMessagingTemplate.convertAndSendToUser(String.valueOf(chatMessage.getUserID()), "/msg", response);

Through code above, the message from Alice will be sent to /user/2/msg, and if Bob subscribe it(also means subscribe himself), he will receive the message.

And Alice should also subscribe herself to receive message sent to her:

stompClient.subscribe('/user/' + 1 + '/msg', function (response) {
    showResponse(JSON.parse(response.body).responseMessage);
});

So when Bob send a message to Alice, she will receive it correctly.

Token-Authorization

Sometimes, we want our endpoint can only be accessed by authorized users. So we need check users' identify.

And I have add an example of passing token through HTTP headers.

For server, we need to receive the header in our endpoint controller method:

private String token = "this is a token generated by your code!";

@MessageMapping("/broadcast")
@SendTo("/b")
public Response say(Message message, @Header(value = "authorization") String authorizationToken) {
    if (authorizationToken.equals(token)) {
        System.out.println("Token check success!!!");
    } else {
        System.out.println("Token check failed!!!");
    }
    return new Response("Welcome, " + message.getName() + "!");
}

When you send a HTTP header authorization with a STOMP SEND method, the authorization token will be received properly.

For browser client, what we should do is add HTTP header in out SEND method:

stompClient.send(
    '/broadcast',
    {
        "authorization": "this is a token generated by your code!"
    },
    JSON.stringify({'name': name})
);

So when we send a message to endpoint /broadcast, the header authorization will be sent as well. And the server will do some check to the authorizationToken.

For android client, it is similar to the browser client:

String token = "this is a token generated by your code!";
StompHeader authorizationHeader = new StompHeader("authorization", token);
stompClient.send(new StompMessage(
        // Stomp command
        StompCommand.SEND,
        // Stomp Headers, Send Headers with STOMP
        // the first header is necessary, and the other can be customized by ourselves
        Arrays.asList(new StompHeader(StompHeader.DESTINATION, Const.broadcast), authorizationHeader),
        // Stomp payload
        jsonObject.toString())
    ).subscribe(...);

So, now we can generate token in server and send the token to users after the successful login. When user want to send message to endpoints we provide, a valid token is required!