# Calculator

**Repository Path**: open-harmony-north/calculator

## Basic Information

- **Project Name**: Calculator
- **Description**: 本例通过计算器 Demo 演示 Worker 的基本用法。
- **Primary Language**: Unknown
- **License**: Apache-2.0
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 1
- **Created**: 2022-08-08
- **Last Updated**: 2022-08-10

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# 计算器 Demo

本例通过计算器 Demo 演示 Worker 的基本用法，效果如下所示：

![success](./asserts/screenshot_success.png)

![failure](./asserts/screenshot_failure.png)

## 使用说明

- IDE：
  ```
    DevEco Studio 3.0 Beta4
    Build Version: 3.0.0.992, built on July 14, 2022
    Runtime version: 11.0.13+7-b1751.21 amd64
    VM: Dynamic Code Evolution 64-Bit Server VM by JetBrains s.r.o.
    Windows 10 10.0
    GC: G1 Young Generation, G1 Old Generation
    Memory: 1536M
    Cores: 8
    Registry: external.system.auto.import.disabled=true
  ```
- SDK：v3.2.5.5
- Model: Stage（API 9）

## 目录介绍

关键目录介绍：

```shell
├─entry
│  │
│  └─src
│      ├─main
│      │  │  module.json5
│      │  │
│      │  ├─ets
│      │  │  ├─Application
│      │  │  │      MyAbilityStage.ts
│      │  │  │
│      │  │  ├─MainAbility
│      │  │  │      MainAbility.ts
│      │  │  │
│      │  │  ├─pages
│      │  │  │      index.ets # 界面逻辑
│      │  │  │
│      │  │  ├─utils
│      │  │  │      calculate.ts # 计算器逻辑
│      │  │  │      logger.ts # 日志封装
│      │  │  │      message.ts # Worker线程与UI主线程之间通信的消息格式
│      │  │  │
│      │  │  └─workers
│      │  │          worker.ts # Worker逻辑
│      │  │
│      │  └─resources # 资源目录
```

## UI主线程

```typescript
import worker from '@ohos.worker';

@Entry
@Component
struct Index {
  // 创建Worker线程，并指定线程中要运行的代码
  private workerInstance = new worker.Worker("/entry/ets/workers/worker.ts", { name: "CalculateWorker" })

  aboutToAppear() {
    // 监听从Worker线程传递过来的数据，并进行业务逻辑处理
    this.workerInstance.onmessage = (event: MessageEvent<Message>) => {
      // 业务逻辑处理
      logger.success(`UI Process receives message: ${JSON.stringify(event.data)}`)
		  if (isSuccess(event.data)) {
		    this.answer = event.data.payload as string;
		    this.hasError = false;
		  } else {
		    this.hasError = true;
		  }
    }
  }
}
```

## Worker线程

```typescript
import worker, { MessageEvent } from '@ohos.worker';
import { parse, transform, calculate } from "../utils/calculate";
import { message, CODE_SUCCESS, CODE_FAILURE } from "../utils/message";
import logger from "../utils/logger";

const parentPort = worker.parentPort;
// 监听从UI主线程传递过来的数据
parentPort.onmessage = function (event: MessageEvent<string>) {
  const expression = event.data;
  logger.success(`Worker Process receives request: ${event.data}`);
  try {
    // 业务逻辑处理
    const answer: string = calculate(transform(parse(expression))).toString();
    logger.success(`Worker Process ponst message: ${answer}`);
    // 将处理好的结果传递会UI主线程
    parentPort.postMessage(message(CODE_SUCCESS, answer));
  } catch (err) {
    logger.error(`Worker Process error: ${err}`);
    // 异常情况也需要通知UI主线程
    parentPort.postMessage(message(CODE_FAILURE));
  }
}

```