harmony 鸿蒙@system.app (Application Context)

2022-08-09
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@system.app (Application Context)

NOTE

The initial APIs of this module are supported since API version 3. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Modules to Import

import app, { AppResponse } from '@system.app'

App

getInfo

static getInfo(): AppResponse

Obtains the declared information in the config.json file of an application.

This API is deprecated since API version 9. You are advised to use bundleManager.getApplicationInfo instead.

System capability: SystemCapability.ArkUI.ArkUI.Lite

Return value

Type	Description
AppResponse	Application response information.

Example

import app, { AppResponse } from '@system.app'
export default class Info {
  getInfo() {
    let info:AppResponse = app.getInfo()
    console.log(JSON.stringify(info))
  }
}

terminate

static terminate(): void

Terminates the current ability.

You are advised to use @ohos.ability.featureAbility since API version 7.

System capability: SystemCapability.ArkUI.ArkUI.Lite

Example

import app, { AppResponse } from '@system.app'
export default class TerM {
  terminate() {
    app.terminate()
  }
}

setImageCacheCount⁷⁺

static setImageCacheCount(value: number): void

Sets the maximum number of decoded images that can be cached in the memory to speed up the loading of images from the same sources. If the input parameter is not set, the default value 0 is used, indicating that images are not cached. The built-in Least Recently Used (LRU) policy is used for caching. If the maximum number is exceeded, the images that have not been updated for the longest time will be removed. You are advised to set the parameter based on the application memory requirements. If the number of images is too large, the memory usage may be too high.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Number of decoded images that are cached in the memory.

Example

// app.ets
import app, { AppResponse } from '@system.app'

export default class OnC {
  onCreate() {
    app.setImageCacheCount(100) // Set the maximum number of decoded images that can be cached in the memory to 100.
    console.info('Application onCreate')
  },
  onDestroy() {
    console.info('Application onDestroy')
  },
}

setImageRawDataCacheSize⁷⁺

static setImageRawDataCacheSize(value: number): void

Sets the maximum size (in bytes) of the image data cached in the memory before decoding to speed up the loading of images from the same sources. If the input parameter is not set, the default value 0 is used, indicating that images are not cached. The LRU policy is used for caching. If the maximum size is exceeded, the images that have not been updated for the longest time will be removed. You are advised to set the parameter based on the application memory requirements. If the image cache is too large, the memory usage may be too high.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Size of the image data cached before decoding, in bytes.

Example

// app.ets
import app, { AppResponse } from '@system.app'

export default class OnC {
  onCreate() {
    app.setImageRawDataCacheSize(104857600)
    // Set the upper limit of the memory for caching image data before decoding to 100 MB. (100 x 1024 x 1024 B =104857600 B = 100 MB).
    console.info('Application onCreate')
  },
  onDestroy() {
    console.info('Application onDestroy')
  },
}

setImageFileCacheSize⁷⁺

static setImageFileCacheSize(value: number): void

Sets the maximum size of the image file cache (in bytes) to speed up the loading of images from the same sources, especially online image sources and thumbnails. If the input parameter is not set, the default value 100 MB is used. The LRU policy is used for caching. If the maximum size is exceeded, the images that have not been updated for the longest time will be removed. You are advised to set the parameter based on the application memory requirements. If the image cache is too large, the disk usage may be too high.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Size of the image file cache, in bytes.

Example

// app.ets
import app, { AppResponse } from '@system.app'

export default class OnC {
  onCreate() {
    app.setImageFileCacheSize(209715200)
    // Set the upper limit of the image file cache to 200 MB. (200 x 1024 x 1024 B= 209715200 B = 200 MB).
    console.info('Application onCreate')
  },
  onDestroy() {
    console.info('Application onDestroy')
  },
}

ScreenOnVisible^(deprecated)

static screenOnVisible(options?: ScreenOnVisibleOptions): void

Defines whether to keep the application visible when the screen is woken up.

This API is deprecated since API Version 8.

System capability: SystemCapability.ArkUI.ArkUI.Full

Name	Type	Mandatory	Description
options	ScreenOnVisibleOptions	No	With keep-alive, the system is prevented from returning to the home screen when the screen is locked, so that the application is visible when the screen is woken up.

requestFullWindow^(deprecated)

static requestFullWindow(options?: RequestFullWindowOptions): void

Requests the application to run in full window. You can call this API when the FA runs in a non-full window, for example, semi-modal FA. This API is invalid for an application already in full-window mode.

You are advised to use @ohos.window since API version 7.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
options	RequestFullWindowOptions	No	Duration for transition from the non-full window to the full window, in milliseconds. By default, the value is in direct proportion to the distance between the non-full window and the full window.

Example

import app, { AppResponse } from '@system.app'
export default class Req {
  requestFullWindow() {
    app.requestFullWindow({
      duration: 200
    })
  }
}

AppResponse

Defines the application response information.

System capability: The items in the table below require different system capabilities. For details, see the table.

Name	Type	Mandatory	Description
appID⁶⁺	string	Yes	Bundle name of an application. It uniquely identifies the application. System capability: SystemCapability.ArkUI.ArkUI.Full
appName	string	Yes	Application name. System capability: SystemCapability.ArkUI.ArkUI.Lite
versionName	string	Yes	Application version name. System capability: SystemCapability.ArkUI.ArkUI.Lite
versionCode	number	Yes	Application version number. System capability: SystemCapability.ArkUI.ArkUI.Lite

ScreenOnVisibleOptions

Defines the options of the visible interface on the screen.

System capability: SystemCapability.ArkUI.ArkUI.Full

Name	Type	Mandatory	Description
visible	boolean	No	Whether to keep the application visible. The default value is false.
success	() => void	No	Callback upon success.
fail	(data: string, code: number) => void	No	Callback upon failure.
complete	() => void	No	Called when the API call is complete.