harmony 鸿蒙Context

2022-12-22
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Context

The Context module provides context for abilities or applications. It allows access to application-specific resources.

NOTE

The initial APIs of this module are supported since API version 9. Newly added APIs will be marked with a superscript to indicate their earliest API version.

The APIs of this module can be used only in the stage model.

Modules to Import

import common from '@ohos.app.ability.common';

Attributes

System capability: SystemCapability.Ability.AbilityRuntime.Core

Name	Type	Readable	Writable	Description
resourceManager	resmgr.ResourceManager	Yes	No	Object for resource management.
applicationInfo	ApplicationInfo	Yes	No	Application information.
cacheDir	string	Yes	No	Cache directory.
tempDir	string	Yes	No	Temporary directory.
filesDir	string	Yes	No	File directory.
databaseDir	string	Yes	No	Database directory.
preferencesDir	string	Yes	No	Preferences directory.
bundleCodeDir	string	Yes	No	Bundle code directory. Do not access resource files by concatenating paths. Use the resourceManager API instead.
distributedFilesDir	string	Yes	No	Distributed file directory.
eventHub	EventHub	Yes	No	Event hub that implements event subscription, unsubscription, and triggering.
area	contextConstant.AreaMode	Yes	No	Encryption level of the directory.

Context.createBundleContext

createBundleContext(bundleName: string): Context;

Creates the context based on the bundle name.

Required permissions: ohos.permission.GET_BUNDLE_INFO_PRIVILEGED

System capability: SystemCapability.Ability.AbilityRuntime.Core

System API: This is a system API and cannot be called by third-party applications.

Parameters

Name	Type	Mandatory	Description
bundleName	string	Yes	Bundle name.

Return value

Type	Description
Context	Context created.

Example

import common from '@ohos.app.ability.common';

let bundleContext: common.Context;
try {
    bundleContext = this.context.createBundleContext('com.example.test');
} catch (error) {
    console.error('createBundleContext failed, error.code: ${error.code}, error.message: ${error.message}');
}

Context.createModuleContext

createModuleContext(moduleName: string): Context;

Creates the context based on the module name.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Name	Type	Mandatory	Description
moduleName	string	Yes	Module name.

Return value

Type	Description
Context	Context created.

Example

import common from '@ohos.app.ability.common';

let moduleContext: common.Context;
try {
    moduleContext = this.context.createModuleContext('entry');
} catch (error) {
    console.error('createModuleContext failed, error.code: ${error.code}, error.message: ${error.message}');
}

NOTE

Only the context of other modules in the current application and the context of the intra-application HSP can be obtained. The context of other applications cannot be obtained.

Context.createModuleContext

createModuleContext(bundleName: string, moduleName: string): Context;

Creates the context based on the bundle name and module name.

System capability: SystemCapability.Ability.AbilityRuntime.Core

System API: This is a system API and cannot be called by third-party applications.

Parameters

Name	Type	Mandatory	Description
bundleName	string	Yes	Bundle name.
moduleName	string	Yes	Module name.

Return value

Type	Description
Context	Context created.

Example

import common from '@ohos.app.ability.common';

let moduleContext: common.Context;
try {
    moduleContext = this.context.createModuleContext('com.example.test', 'entry');
} catch (error) {
    console.error('createModuleContext failed, error.code: ${error.code}, error.message: ${error.message}');
}

Context.getApplicationContext

getApplicationContext(): ApplicationContext;

Obtains the context of this application.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Return value

Type	Description
ApplicationContext	Application context obtained.

Example

import common from '@ohos.app.ability.common';

let applicationContext: common.Context;
try {
    applicationContext = this.context.getApplicationContext();
} catch (error) {
    console.error('getApplicationContext failed, error.code: ${error.code}, error.message: ${error.message}');
}

Context.getGroupDir¹⁰⁺

getGroupDir(dataGroupID: string): Promise<string>;

Obtains the shared directory based on a group ID. This API uses a promise to return the result.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Name	Type	Mandatory	Description
dataGroupID	string	Yes	Group ID, which is assigned by the system when an atomic service application project is created.

Return value

Type	Description
Promise<string>	Promise used to return the result. If no shared directory exists, null is returned. Only the encryption level EL2 is supported.

Error codes

For details about the error codes, see Ability Error Codes.

ID	Error Message
16000011	The context does not exist.

Example

import common from '@ohos.app.ability.common';

let groupId = "1";
let getGroupDirContext: common.Context = this.context;
try {
  getGroupDirContext.getGroupDir(groupId).then(data => {
    console.log("getGroupDir result:" + data);
  })
} catch (error) {
  console.error('getGroupDirContext failed, error.code: ${error.code}, error.message: ${error.message}');
}

Context.getGroupDir¹⁰⁺

getGroupDir(dataGroupID: string, callback: AsyncCallback<string>): void;

Obtains the shared directory based on a group ID. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Name	Type	Mandatory	Description
dataGroupID	string	Yes	Group ID, which is assigned by the system when an atomic service application project is created.
callback	AsyncCallback<string>	Yes	Callback used to return the result. If no shared directory exists, null is returned. Only the encryption level EL2 is supported.

Error codes

For details about the error codes, see Ability Error Codes.

ID	Error Message
16000011	The context does not exist.

Example

import common from '@ohos.app.ability.common';

let getGroupDirContext: common.Context = this.context;

getGroupDirContext.getGroupDir("1", (err, data) => {
  if (err) {
    console.error(`getGroupDir faile, err: ${JSON.stringify(err)}`);
  } else {
    console.log(`getGroupDir result is: ${JSON.stringify(data)}`);
  }
});