Socket Mode

String appToken = "xapp-";
App app = new App();
SocketModeApp socketModeApp = new SocketModeApp(
  appToken,
  SocketModeClient.Backend.JavaWebSocket,
  app
);
socketModeApp.start();

import com.slack.api.bolt.App;
import com.slack.api.bolt.AppConfig;
import com.slack.api.model.event.AppMentionEvent;

// The bot token that starts with xoxb- is NOT the app-level token.
// The token here is the one you got by installing the app into a workspace
String botToken = System.getenv("SLACK_BOT_TOKEN");
AppConfig appConfig = AppConfig.builder().singleTeamBotToken(botToken).build();
// If you go with the default constructor, the App initialization requires an env variable named SLACK_BOT_TOKEN.
App app = new App(appConfig);

app.event(AppMentionEvent.class, (req, ctx) -> {
  ctx.say("Hi there!");
  return ctx.ack();
});

import com.slack.api.bolt.socket_mode.SocketModeApp;

// the app-level token with `connections:write` scope
String appToken = System.getenv("SLACK_APP_TOKEN");

// Initialize the adapter for Socket Mode
// with an app-level token and your Bolt app with listeners.
SocketModeApp socketModeApp = new SocketModeApp(appToken, app);

// #start() method establishes a new WebSocket connection and then blocks the current thread.
// If you do not want to block this thread, use #startAsync() instead.
socketModeApp.start();

import com.slack.api.bolt.App;
import com.slack.api.bolt.AppConfig;
import com.slack.api.model.event.AppMentionEvent;

// As this is a distributed Socket Mode app,
// you do not need a token for a specific workspace and the signing secret here.
AppConfig appConfig = AppConfig.builder()
  .clientId("111.222")
  .clientSecret("xxx")
  .scope("app_mentions:read,chat:write,commands")
  .oauthInstallPath("install")
  .oauthRedirectUriPath("oauth_redirect")
  .build();

// Initialize the App and register listeners
App app = new App(appConfig);
app.event(AppMentionEvent.class, (req, ctx) -> {
  ctx.say("Hi there!");
  return ctx.ack();
});

// ------------------------------
// Start a new thread that runs the Socket Mode app in this process
import com.slack.api.bolt.socket_mode.SocketModeApp;

String appToken = "xapp-1-A111-111-xxx";
SocketModeApp socketModeApp = new SocketModeApp(appToken, app);

// This does not block the current thread
socketModeApp.startAsync();

// ------------------------------
// Start an embedded Jetty Web server in this process
import com.slack.api.bolt.jetty.SlackAppServer;
import java.util.HashMap;
import java.util.Map;

Map<String, App> apps = new HashMap<>();
apps.put("/slack/", new App(appConfig).asOAuthApp(true));
SlackAppServer oauthSever = new SlackAppServer(apps);

// Block the current thread
oauthSever.start();

// Access the OAuth URL - https://{your public domain}/slack/install

import com.slack.api.Slack;
import com.slack.api.socket_mode.SocketModeClient;
import com.slack.api.socket_mode.request.EventsApiEnvelope;
import com.slack.api.socket_mode.response.AckResponse;
import com.slack.api.socket_mode.response.SocketModeResponse;

String appLevelToken = "xapp-A111-222-xxx";

// Issue a new WSS URL and set the value to the client
try (SocketModeClient client = Slack.getInstance().socketMode(appLevelToken)) {
  // SocketModeClient has #close() method

  // Add a listener function to handle all raw WebSocket text messages
  // You can handle not only envelopes but also any others such as "hello" messages.
  client.addWebSocketMessageListener((String message) -> {
    // TODO: Do something with the raw WebSocket text message
  });

  client.addWebSocketErrorListener((Throwable reason) -> {
    // TODO: Do something with a thrown exception
  });

  // Add a listener function that handles only type: events envelopes
  client.addEventsApiEnvelopeListener((EventsApiEnvelope envelope) -> {
    // TODO: Do something with an Events API payload

    // Acknowledge the request (within 3 seconds)
    SocketModeResponse ack = AckResponse.builder().envelopeId(envelope.getEnvelopeId()).build();
    client.sendSocketModeResponse(ack);
  });

  client.connect(); // Start receiving messages from the Socket Mode server

  client.disconnect(); // Disconnect from the server

  client.connectToNewEndpoint(); // Issue a new WSS URL and connects to the URL
}