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标题: HarmonyOSNEXT—应用通信之Emitter [打印本页]

作者: ouyangzhi 时间: 2025-3-27 12:31
标题: HarmonyOSNEXT—应用通信之Emitter
[md]# HarmonyOSNEXT—应用通信之Emitter

## 序言

在应用开发过程中，我们对于应用中数据和响应事件的传递，都会选择不同的通信方式，在选择这些通信方式时，我们需要考虑不同通信方式下我们的实现逻辑，以及是否满足我们的需求，本文主要介绍，应用在同一进程的通信方式

## 一、基于同进程的通信方式——Emitter

### 简介：

Emitter提供在同一进程不同线程，或者同一进程同一线程的通信方式，在应用开发中通常被用作组件间，或者窗口间传递消息；注意如果跨线程传递数据，数据是会被自动序列化的

### 使用方式：

```tsx
// 单次订阅，收到回调后，自动取消订阅
emitter.once({eventId: 1}, () => {
   console.info('once callback');
});
emitter.once("onceClick", () => {
   console.info('once onClick callback');
});
```

```tsx
// 持续订阅事件，没有取消订阅就会一直接收消息
emitter.on({eventId: 2}, () => {
   console.info('once callback');
});
emitter.on("Click", () => {
   console.info('on onClick callback');
});
```

```tsx
let eventData: emitter.EventData = {
   data: {
      "once": "send",
   }
};
// 发送指定事件
emitter.emit({eventId: 1}, eventData)
emitter.emit("onceClick" , eventData)
emitter.emit("onceClick" ,{ priority: emitter.EventPriority.HIGH }, eventData)
```

```tsx
// 取消事件的订阅
emitter.off(2)
emitter.off("Click")
// 取消指定回调的事件订阅
emitter.off(1, callback)
emitter.off("onceClick", callback)
```

## 二、项目示例：

使用Emitter来完成跨窗口传递消息，并在指定页面进行刷新，主要用于在同一进程下，不同的窗口或者不同上下文间传递消息

```tsx
// index.ets
import { emitter } from '@kit.BasicServicesKit';
import { MyWindowManager } from '../util/windowManger';

@Entry
@Component
struct Index {
  @State message: string = 'Hello World';

  aboutToAppear(): void {
emitter.on('click', (data) => {
   let result = data.data
   this.message = result?.TestEmitter
   MyWindowManager.getInstance().closeDialog("testEmitterDialog")
})
  }

  build() {
Column({space: 20}) {
   Text(this.message).fontSize(50).fontWeight(FontWeight.Bold).margin({top: 50})
   Button("第一个弹框")
      .fontSize(50)
      .fontWeight(FontWeight.Bold)
      .onClick(() => {
      MyWindowManager.getInstance().showDialogView("testEmitterDialog", 0)
      })
}
.height('100%')
.width('100%')
  }
}

// TestEmitter.ets
import { emitter } from '@kit.BasicServicesKit';

@Entry
@Component
struct TestEmitter {
  @State message: string = 'TestEmitter';

  build() {
Column({space: 20}) {
   Text("这是一个弹框").fontSize(50)
      .fontWeight(FontWeight.Bold)
   Button("点击弹框发送消息")
      .fontSize(26)
      .fontWeight(FontWeight.Bold)
      .onClick(() => {
      emitter.emit('click', {
         data: {
            "TestEmitter": this.message
         }
      })
      })
}
.height('100%')
.width('100%')
  }
}

// windowManger.ets
import window from '@ohos.window';
import { display } from '@kit.ArkUI';

const TAG = "WindowManager"
export class MyWindowManager {

  static getInstance(): MyWindowManager {
if (globalThis.mWindowManager == null) {
   globalThis.mWindowManager = new MyWindowManager();
}
return globalThis.mWindowManager;
  }

  showDialogView(dialogName: string, offsetY: number) {
console.log(TAG, "showDialogView")
let dialogView = AppStorage.get(dialogName) as window.Window;
if (dialogView) {
   console.log(TAG, "dialogView  showWindow")
   dialogView.showWindow(() => {
      dialogView.setWindowFocusable(true);
      dialogView.setWindowTouchable(true);
   });
} else {
   console.log(TAG, "dialogView is undefined ");
   this.createDialogWindow(dialogName, offsetY);
}
  }

  closeDialog(dialogName: string) {
try {
   let dialogView = AppStorage.get(dialogName) as window.Window
   if (!dialogView) {
      console.log(TAG, "dialogView is null")
   }
   dialogView.destroyWindow()
   AppStorage.set(dialogName, null)
} catch (e) {
   console.error(TAG, 'close window err' + JSON.stringify(e))
}
  }

  /**
* 创建Dialog提示窗口
*/
  async createDialogWindow(dialogName: string, offsetY: number) {
try {
   let config: window.Configuration = {
      ctx: globalThis.context,
      name: dialogName,
      windowType: window.WindowType.TYPE_DIALOG
   }
   let win = await window.createWindow(config)
   await win.setPreferredOrientation(window.Orientation.UNSPECIFIED);
   await win.setUIContent('pages/' + "TestEmitter")
   let dis = display.getDefaultDisplaySync()
   console.log(TAG, "dis.height: " + dis.height)
   await win.resize(dis.width -100, 300)
   await win.moveWindowTo(50, dis.height - vp2px(300) - vp2px(offsetY))
   await win.showWindow()
   win.setWindowBackgroundColor('#33000000')
   win.setWindowFocusable(true)
   win.setWindowTouchable(true)
   AppStorage.setOrCreate(dialogName, win)
} catch (e) {
   console.error(TAG, 'createDialogWindow err = ' + JSON.stringify(e))
}
  }
}

```
[/md]

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