@ohos.app.ability.appRecovery (appRecovery)

The appRecovery module provides APIs for recovering faulty applications.

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. In API version 9, only applications with a single ability in a process can be recovered. In API version 10, applications with multiple abilities in a process can be recovered.

Modules to Import

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

appRecovery.RestartFlag

Enumerates the application restart flags. This enum is used as an input parameter of enableAppRecovery.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Name	Value	Description
ALWAYS_RESTART	0	The application is restarted in all cases.
RESTART_WHEN_JS_CRASH	0x0001	The application is restarted in the case of JS_CRASH.
RESTART_WHEN_APP_FREEZE	0x0002	The application is restarted in the case of APP_FREEZE.
NO_RESTART	0xFFFF	The application is not restarted in any case.

appRecovery.SaveOccasionFlag

Enumerates the scenarios for saving the application state. This enum is used as an input parameter of enableAppRecovery.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Name	Value	Description
SAVE_WHEN_ERROR	0x0001	Saving the application state when an application fault occurs.
SAVE_WHEN_BACKGROUND	0x0002	Saving the application state when the application is switched to the background.

appRecovery.SaveModeFlag

Enumerates the application state saving modes. This enum is used as an input parameter of enableAppRecovery.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Name	Value	Description
SAVE_WITH_FILE	0x0001	The application state is saved and written to the local file cache.
SAVE_WITH_SHARED_MEMORY	0x0002	The application state is saved in the memory. When the application exits due to a fault, it is written to the local file cache.

appRecovery.enableAppRecovery

enableAppRecovery(restart?: RestartFlag, saveOccasion?: SaveOccasionFlag, saveMode?: SaveModeFlag) : void;

Enables application recovery. After this API is called, the first ability that is displayed when the application is started from the initiator can be restored.

Model restriction: This API can be used only in the stage model.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Name	Type	Mandatory	Description
restart	RestartFlag	No	Whether the application is restarted upon a fault. By default, the application is not restarted.
saveOccasion	SaveOccasionFlag	No	Scenario for saving the application state. By default, the state is saved when a fault occurs.
saveMode	SaveModeFlag	No	Application state saving mode. By default, the application state is written to the local file cache.

Example

import appRecovery from '@ohos.app.ability.appRecovery';
import AbilityStage from '@ohos.app.ability.AbilityStage';

export default class MyAbilityStage extends AbilityStage {
    onCreate() {
        appRecovery.enableAppRecovery(
            appRecovery.RestartFlag.ALWAYS_RESTART,
            appRecovery.SaveOccasionFlag.SAVE_WHEN_ERROR,
            appRecovery.SaveModeFlag.SAVE_WITH_FILE
        );
    }
}

appRecovery.restartApp

restartApp(): void;

Restarts the current process and starts the first ability that is displayed when the application is started. If the state of this ability is saved, the saved state data is passed into the wantParam attribute in the want parameter of the onCreate lifecycle callback of the ability.

In API version 10, the ability specified by setRestartWant is started. If no ability is specified, the following rules are used:

If the ability of the current application running in the foreground supports recovery, that ability is started.
If multiple abilities that support recovery is running in the foreground, only the last ability is started.
If no ability is running in the foreground, none of them is started.

This API can be used together with the APIs of errorManager.

Model restriction: This API can be used only in the stage model.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Example

import appRecovery from '@ohos.app.ability.appRecovery';
import errorManager from '@ohos.app.ability.errorManager';

let observer: errorManager.ErrorObserver = {
    onUnhandledException(errorMsg) {
        console.log('onUnhandledException, errorMsg: ', errorMsg);
        appRecovery.restartApp();
    }
};

try {
    errorManager.on('error', observer);
} catch (paramError) {
    console.error(`error: ${paramError.code}, ${paramError.message}`);
}

appRecovery.saveAppState

saveAppState(): boolean;

Saves the application state. This API can be used together with the APIs of errorManager.

Model restriction: This API can be used only in the stage model.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Return value

Type	Description
boolean	Whether the application state is saved. The value true is returned if the application state is saved, and false is returned otherwise.

Example

import appRecovery from '@ohos.app.ability.appRecovery';
import errorManager from '@ohos.app.ability.errorManager';

let observer: errorManager.ErrorObserver = {
    onUnhandledException(errorMsg) {
        console.log('onUnhandledException, errorMsg: ', errorMsg);
        appRecovery.saveAppState();
    }
};

try {
    errorManager.on('error', observer);
} catch (paramError) {
    console.error(`error: ${paramError.code}, ${paramError.message}`);
}

appRecovery.saveAppState¹⁰⁺

saveAppState(context?: UIAbilityContext): boolean;

Saves the ability state, which will be used for recovery. This API can be used together with the APIs of errorManager.

Model restriction: This API can be used only in the stage model.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Name	Type	Mandatory	Description
context	UIAbilityContext	No	UIAbility context.

Return value

Type	Description
boolean	Whether the application state is saved. The value true is returned if the application state is saved, and false is returned otherwise.

Example

import appRecovery from '@ohos.app.ability.appRecovery';
import errorManager from '@ohos.app.ability.errorManager';

let observer: errorManager.ErrorObserver = {
    onUnhandledException(errorMsg) {
        console.log('onUnhandledException, errorMsg: ', errorMsg);
        appRecovery.saveAppState(this.context);
    }
};

try {
    errorManager.on('error', observer);
} catch (paramError) {
    console.error(`error: ${paramError.code}, ${paramError.message}`);
}

appRecovery.setRestartWant¹⁰⁺

setRestartWant(want: Want): void;

Sets an ability that will be recovered. The ability must be a UIAbility in the current bundle.

Model restriction: This API can be used only in the stage model.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Name	Type	Mandatory	Description
want	Want	Yes	Want of the target ability. You can set the bundleName and abilityName fields in Want to specify the ability.

Example

import appRecovery from '@ohos.app.ability.appRecovery';
import Want from '@ohos.app.ability.Want';

Button ("Start to Recover Ability")
    .fontSize(40)
    .fontWeight(FontWeight.Bold)
    .onClick(()=> {
        // set restart want
        let want: Want = {
            bundleName: "ohos.samples.recovery",
            abilityName: "RecoveryAbility"
        };

        appRecovery.setRestartWant(want);
    })