如何在 android 上通过 spring 启动从 stomp websocket 接收消息？

Question

我从https://spring.io/guides/gs/messaging-stomp-websocket/得到了简单的 WebSocket 示例

package com.example.chatservice.message;

import org.springframework.context.annotation.Configuration;
import org.springframework.messaging.simp.config.MessageBrokerRegistry;
import org.springframework.web.socket.config.annotation.EnableWebSocketMessageBroker;
import org.springframework.web.socket.config.annotation.StompEndpointRegistry;
import org.springframework.web.socket.config.annotation.WebSocketMessageBrokerConfigurer;

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {

    @Override
    public void configureMessageBroker(MessageBrokerRegistry config) {
        config.enableSimpleBroker("/topic");
        config.setApplicationDestinationPrefixes("/app");
    }

    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        registry.addEndpoint("/gs-guide-websocket").withSockJS();
    }
}

@Controller
public class ChatController {
    @MessageMapping("/hello")
    @SendTo("/topic/greetings")
    public Greeting greeting(HelloMessage message) throws Exception {
        return new Greeting("Hello from chat!");
    }
}

我想从 spring 服务器接收到 android 应用程序的Greeting消息。 我使用https://github.com/NaikSoftware/StompProtocolAndroid作为 stomp 客户端

package com.example.chatapp;

import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.widget.Button;

import androidx.appcompat.app.AppCompatActivity;

import org.java_websocket.WebSocket;

import ua.naiksoftware.stomp.Stomp;
import ua.naiksoftware.stomp.client.StompClient;

public class MainActivity extends AppCompatActivity {
    private StompClient mStompClient;
    public static  final String TAG="StompClient";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button view = (Button) findViewById(R.id.send_message);
        view.setOnClickListener(e->  new StompTask().execute(""));
    }

    private static class StompTask extends AsyncTask<String, Void, String> {
        private StompClient mStompClient;
        String TAG="LongOperation";

        @Override
        protected String doInBackground(String... params) {
            mStompClient = Stomp.over(WebSocket.class, "http://10.0.2.2:8080/gs-guide-websocket/websocket");
            mStompClient.connect();

            mStompClient.topic("/topic/greetings").subscribe(topicMessage -> {
                Log.d(TAG, topicMessage.getPayload());
            });

            mStompClient.lifecycle().subscribe(lifecycleEvent -> {
                switch (lifecycleEvent.getType()) {

                    case OPENED:
                        Log.d(TAG, "Stomp connection opened");
                        break;

                    case ERROR:
                        Log.e(TAG, "Error", lifecycleEvent.getException());
                        break;

                    case CLOSED:
                        Log.d(TAG, "Stomp connection closed");
                        break;
                }
            });

            return "Executed";
        }
    }
}

和连接到

http://10.0.2.2:8080/gs-guide-websocket/websocket

有效，因为日志显示它已连接

2022-01-18 14:04:56.486 23717-23752/com.example.chatapp D/LongOperation: Stomp connection opened

但它不订阅主题：

mStompClient.topic("/topic/greetings").subscribe(topicMessage -> {
    Log.d(TAG, topicMessage.getPayload());
});

因为当我设置断点时，它永远不会命中它。

我怎样才能收到这条消息？

Answer 1

我认为一切看起来都很棒，除了 websocket 的"http://10.0.2.2:8080/gs-guide-websocket/websocket"应该是"ws://10.0.2.2:8080/gs-guide-websocket/websocket" .

图书馆的作者把这个放在他们的示例代码中：

`mStompClient = Stomp.over(Stomp.ConnectionProvider.OKHTTP, "ws://" + ANDROID_EMULATOR_LOCALHOST + ":" + RestClient.SERVER_PORT + "/example-endpoint/websocket");` 

Answer 2

首先，我想您明白，如果您没有向指定的请求主题发送正确的消息，那么您将不会在这里得到任何东西 -

mStompClient.topic("/topic/greetings").subscribe(topicMessage -> {
    Log.d(TAG, topicMessage.getPayload());
});

今天我在发送消息时遇到了问题，

mStompClient.send(REQUEST_TOPIC, requestAsString)

我也没有收到订阅中的任何内容。 问题是除了订阅接收消息的主题，还必须订阅发送消息的主题——

mStompClient.send(REQUEST_TOPIC, requestAsString)
                        .subscribeOn(Schedulers.io())
                        .observeOn(AndroidSchedulers.mainThread())
                        .subscribe(
                                {
                                //onComplete
                                }, { error ->
                                  error.safeLog()
                                })