Using Emitter for Inter-Thread Communication

Emitter provides APIs for sending and processing events between threads, including the APIs for processing events that are subscribed to in persistent or one-shot manner, unsubscribing from events, and emitting events to the event queue.

To develop the Emitter mode, perform the following steps:

Subscribe to an event.

import emitter from "@ohos.events.emitter";

// Define an event with eventId 1.
let event: emitter.InnerEvent = {
  eventId: 1
};

// Trigger the callback after the event with eventId 1 is received.
let callback = (eventData: emitter.EventData) => {
  console.info('event callback');
};

// Subscribe to the event with eventId 1.
emitter.on(event, callback);

Emit the event.

import emitter from "@ohos.events.emitter";

// Define an event with eventId 1 and priority Low.
let event: emitter.InnerEvent = {
  eventId: 1,
  priority: emitter.EventPriority.LOW
};

let data = new Map<string, Object>();
data.set("content", "c");
data.set("id", 1);
data.set("isEmpty", false);
let eventData: emitter.EventData = {data};

// Emit the event with eventId 1 and event content eventData.
emitter.emit(event, eventData);