@ohos.file.backup (Backup and Restoration)

The file.backup module provides APIs for backing up and restoring data for applications.

NOTE

• The initial APIs of this module are supported since API version 10. Newly added APIs will be marked with a superscript to indicate their earliest API version.
• The APIs provided by this module are system APIs.

Modules to Import

import backup from '@ohos.file.backup';

FileMeta

Defines a file metadata object, which includes the application name and file URI. FileMeta is an indispensable object for data backup and restoration.

System capability: SystemCapability.FileManagement.StorageService.Backup

FileData

Defines a file data object, which includes the file descriptor (FD) of the file opened. FileData is an indispensable object for data backup and restoration.

NOTE

The FileData must be closed after being used. Otherwise, memory leakage may occur. For details about how to close a FileData object, see fs.closeSync provided by @ohos.file.fs.

System capability: SystemCapability.FileManagement.StorageService.Backup

File

Defines a file object, which inherits from FileMeta and FileData.

NOTE

file.backup.File is different from File provided in @ohos.file.fs. The former is an object that inherits from FileMeta and FileData, while the latter has only one FD object. Pay attention to the difference between them.

System capability: SystemCapability.FileManagement.StorageService.Backup

GeneralCallbacks

Provides callbacks to be used in the backup or restoration process. The backup service uses these callbacks to notify the client of the backup/restoration phase of the application.

System capability: SystemCapability.FileManagement.StorageService.Backup

onFileReady

onFileReady : AsyncCallback<File>

Called when the server sends a file to the client. If the file is sent successfully, err is undefined. Otherwise, err is an error object.

NOTE

The File returned by AsyncCallback is the file.backup.File. The returned file belongs to the backup service. Once the file is closed, the backup service shall clear the resources used by the file at the proper time. However, the client must close the file handle first.

System capability: SystemCapability.FileManagement.StorageService.Backup

Error codes

For details about the error codes, see File Management Error Codes.

Example

  import fs from '@ohos.file.fs';
  import { BusinessError } from '@ohos.base';
  onFileReady: (err: BusinessError, file: backup.File) => {
    if (err) {
      console.error('onFileReady failed with err: ' + JSON.stringify(err));
    }
    console.info('onFileReady success with file: ' + file.bundleName + ' ' + file.uri);
    fs.closeSync(file.fd);
  }

onBundleBegin

onBundleBegin : AsyncCallback<string>

Called when the backup or restoration of an application begins. If the backup or restoration begins, err is undefined. Otherwise, err is an error object.

System capability: SystemCapability.FileManagement.StorageService.Backup

Error codes

For details about the error codes, see File Management Error Codes.

Example

  import { BusinessError } from '@ohos.base';
  onBundleBegin: (err: BusinessError, bundleName: string) => {
    if (err) {
      console.error('onBundleBegin failed with err: ' + JSON.stringify(err));
    }
    console.info('onBundleBegin success with bundleName: ' + bundleName);
  }

onBundleEnd

onBundleEnd : AsyncCallback<string>

Called when the backup or restoration of an application ends. If the backup or restoration ends successfully, err is undefined. Otherwise, err is an error object.

System capability: SystemCapability.FileManagement.StorageService.Backup

Error codes

For details about the error codes, see File Management Error Codes.

Example

  import { BusinessError } from '@ohos.base';
  onBundleEnd: (err: BusinessError, bundleName: string) => {
    if (err) {
      console.error('onBundleEnd failed with err: ' + JSON.stringify(err));
    }
    console.info('onBundleEnd success with bundleName: ' + bundleName);
  }

onAllBundlesEnd

onAllBundlesEnd : AsyncCallback<undefined>

Called when the backup or restoration of all bundles ends. If the backup or restoration of all bundles ends, err is undefined. Otherwise, err is an error object.

System capability: SystemCapability.FileManagement.StorageService.Backup

Error codes

For details about the error codes, see File Management Error Codes.

Example

  import { BusinessError } from '@ohos.base';
  onAllBundlesEnd: (err: BusinessError) => {
    if (err) {
      console.error('onAllBundlesEnd failed with err: ' + JSON.stringify(err));
    }
    console.info('onAllBundlesEnd success');
  }

onBackupServiceDied

onBackupServiceDied : Callback<undefined>

Called when the backup service is suspended.

System capability: SystemCapability.FileManagement.StorageService.Backup

Example

  onBackupServiceDied: () => {
    console.info('onBackupServiceDied success');
  }

backup.getLocalCapabilities

getLocalCapabilities(callback: AsyncCallback<FileData>): void

Obtains a JSON file that describes local capabilities. This API uses an asynchronous callback to return the result.

Required permissions: ohos.permission.BACKUP

System capability: SystemCapability.FileManagement.StorageService.Backup

Parameters

Error codes

For details about the error codes, see File Management Error Codes.

Example

  import fs from '@ohos.file.fs';
  import { BusinessError } from '@ohos.base';
  try {
    backup.getLocalCapabilities((err: BusinessError, fileData: backup.FileData) => {
      if (err) {
        console.error('getLocalCapabilities failed with err: ' + JSON.stringify(err));
      }
      console.info('getLocalCapabilities success');
      fs.closeSync(fileData.fd);
    });
  } catch (error) {
    let err: BusinessError = error as BusinessError;
    console.error('getLocalCapabilities failed with err: ' + JSON.stringify(err));
  }

The following is an example of the file obtained:

 {
  "bundleInfos" :[{
    "allToBackup" : true,
    "extensionName" : "BackupExtensionAbility",
    "name" : "com.example.hiworld",
    "needToInstall" : false,
    "spaceOccupied" : 0,
    "versionCode" : 1000000,
    "versionName" : "1.0.0"
    }],
  "deviceType" : "default",
  "systemFullName" : "OpenHarmony-4.0.0.0"
 }

backup.getLocalCapabilities

getLocalCapabilities(): Promise<FileData>

Obtains a JSON file that describes local capabilities. This API uses a promise to return the result.

Required permissions: ohos.permission.BACKUP

System capability: SystemCapability.FileManagement.StorageService.Backup

Return value

Error codes

For details about the error codes, see File Management Error Codes.

Example

  import fs from '@ohos.file.fs';
  import { BusinessError } from '@ohos.base';
  async function getLocalCapabilities() {
    try {
      let fileData = await backup.getLocalCapabilities();
      console.info('getLocalCapabilities success');
      fs.closeSync(fileData.fd);
    } catch (error) {
      let err: BusinessError = error as BusinessError;
      console.error('getLocalCapabilities failed with err: ' + JSON.stringify(err));
    }
  }

The following is an example of the file obtained:

 {
  "bundleInfos" :[{
    "allToBackup" : true,
    "extensionName" : "BackupExtensionAbility",
    "name" : "com.example.hiworld",
    "needToInstall" : false,
    "spaceOccupied" : 0,
    "versionCode" : 1000000,
    "versionName" : "1.0.0"
    }],
  "deviceType" : "default",
  "systemFullName" : "OpenHarmony-4.0.0.0"
 }

SessionBackup

Provides a backup process object to support the application backup process. Before using the APIs of this class, you need to create a SessionBackup instance.

constructor

constructor(callbacks: GeneralCallbacks);

A constructor used to create a SessionBackup instance.

Required permissions: ohos.permission.BACKUP

System capability: SystemCapability.FileManagement.StorageService.Backup

Parameters

Example

  import fs from '@ohos.file.fs';
  import { BusinessError } from '@ohos.base';
  let generalCallbacks: backup.GeneralCallbacks = {
    onFileReady: (err: BusinessError, file: backup.File) => {
      if (err) {
        console.error('onFileReady failed with err: ' + JSON.stringify(err));
      }
      console.info('onFileReady success');
      fs.closeSync(file.fd);
    },
    onBundleBegin: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleBegin failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleBegin success');
    },
    onBundleEnd: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleEnd success');
    },
    onAllBundlesEnd: (err: BusinessError) => {
      if (err) {
        console.error('onAllBundlesEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onAllBundlesEnd success');
    },
    onBackupServiceDied: () => {
      console.info('service died');
    }
  };
  let sessionBackup = new backup.SessionBackup(generalCallbacks);

appendBundles

appendBundles(bundlesToBackup: string[], callback: AsyncCallback<void>): void

Appends the applications whose data needs to be backed up. Currently, the obtained SessionBackup instance can be called only once in the entire backup process. This API uses an asynchronous callback to return the result.

Required permissions: ohos.permission.BACKUP

System capability: SystemCapability.FileManagement.StorageService.Backup

Parameters

Error codes

For details about the error codes, see File Management Error Codes.

Example

  import fs from '@ohos.file.fs';
  import { BusinessError } from '@ohos.base';
  let generalCallbacks: backup.GeneralCallbacks = {
    onFileReady: (err: BusinessError, file: backup.File) => {
      if (err) {
        console.error('onFileReady failed with err: ' + JSON.stringify(err));
      }
      console.info('onFileReady success');
      fs.closeSync(file.fd);
    },
    onBundleBegin: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleBegin failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleBegin success');
    },
    onBundleEnd: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleEnd success');
    },
    onAllBundlesEnd: (err: BusinessError) => {
      if (err) {
        console.error('onAllBundlesEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onAllBundlesEnd success');
    },
    onBackupServiceDied: () => {
      console.info('service died');
    }
  };
  let sessionBackup = new backup.SessionBackup(generalCallbacks);
  try {
    let backupApps: Array<string> = [
      "com.example.hiworld",
    ];
    sessionBackup.appendBundles(backupApps, (err: BusinessError) => {
      if (err) {
        console.error('appendBundles failed with err: ' + JSON.stringify(err));
      }
      console.info('appendBundles success');
    });
  } catch (error) {
    let err: BusinessError = error as BusinessError;
    console.error('appendBundles failed with err: ' + JSON.stringify(err));
  }

appendBundles

appendBundles(bundlesToBackup: string[]): Promise<void>

Appends the applications whose data needs to be backed up. Currently, the obtained SessionBackup instance can be called only once in the entire backup process. This API uses a promise to return the result.

Required permissions: ohos.permission.BACKUP

System capability: SystemCapability.FileManagement.StorageService.Backup

Parameters

Return value

Error codes

For details about the error codes, see File Management Error Codes.

Example

  import fs from '@ohos.file.fs';
  import { BusinessError } from '@ohos.base';
  let generalCallbacks: backup.GeneralCallbacks = {
    onFileReady: (err: BusinessError, file: backup.File) => {
      if (err) {
        console.error('onFileReady failed with err: ' + JSON.stringify(err));
      }
      console.info('onFileReady success');
      fs.closeSync(file.fd);
    },
    onBundleBegin: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleBegin failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleBegin success');
    },
    onBundleEnd: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleEnd success');
    },
    onAllBundlesEnd: (err: BusinessError) => {
      if (err) {
        console.error('onAllBundlesEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onAllBundlesEnd success');
    },
    onBackupServiceDied: () => {
      console.info('service died');
    }
  };
  let sessionBackup = new backup.SessionBackup(generalCallbacks);
  async function appendBundles() {
    try {
      let backupApps: Array<string> = [
        "com.example.hiworld",
      ];
      await sessionBackup.appendBundles(backupApps);
      console.info('appendBundles success');
    } catch (error) {
    let err: BusinessError = error as BusinessError;
    console.error('appendBundles failed with err: ' + JSON.stringify(err));
    }
  }

SessionRestore

Provides an object to support the application recovery process. Before using the APIs of this class, you need to create a SessionRestore instance.

constructor

constructor(callbacks: GeneralCallbacks);

A constructor used to create a SessionRestore instance.

Required permissions: ohos.permission.BACKUP

System capability: SystemCapability.FileManagement.StorageService.Backup

Parameters

Example

  import fs from '@ohos.file.fs';
  import { BusinessError } from '@ohos.base';
  let generalCallbacks: backup.GeneralCallbacks = {
    onFileReady: (err: BusinessError, file: backup.File) => {
      if (err) {
        console.error('onFileReady failed with err: ' + JSON.stringify(err));
      }
      console.info('onFileReady success');
      fs.closeSync(file.fd);
    },
    onBundleBegin: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleBegin failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleBegin success');
    },
    onBundleEnd: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleEnd success');
    },
    onAllBundlesEnd: (err: BusinessError) => {
      if (err) {
        console.error('onAllBundlesEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onAllBundlesEnd success');
    },
    onBackupServiceDied: () => {
      console.info('service died');
    }
  };
  let sessionRestore = new backup.SessionRestore(generalCallbacks);

appendBundles

appendBundles(remoteCapabilitiesFd: number, bundlesToBackup: string[], callback: AsyncCallback<void>): void

Appends the applications whose data needs to be restored. Currently, the obtained SessionRestore instance can be called only once in the entire restoration process. This API uses an asynchronous callback to return the result.

NOTE

• During the data restoration, the capability file needs to be verified.
• Therefore, remoteCapabilitiesFd can be obtained by using the getLocalCapabilities API provided by the backup service. You can modify the parameters based on the actual situation of your application. You can also use the JSON file example provided by getLocalCapabilities to generate a capability file.

Required permissions: ohos.permission.BACKUP

System capability: SystemCapability.FileManagement.StorageService.Backup

Parameters

Error codes

For details about the error codes, see File Management Error Codes.

Example

  import fs from '@ohos.file.fs';
  import { BusinessError } from '@ohos.base';
  let generalCallbacks: backup.GeneralCallbacks = {
    onFileReady: (err: BusinessError, file: backup.File) => {
      if (err) {
        console.error('onFileReady failed with err: ' + JSON.stringify(err));
      }
      console.info('onFileReady success');
      fs.closeSync(file.fd);
    },
    onBundleBegin: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleBegin failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleBegin success');
    },
    onBundleEnd: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleEnd success');
    },
    onAllBundlesEnd: (err: BusinessError) => {
      if (err) {
        console.error('onAllBundlesEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onAllBundlesEnd success');
    },
    onBackupServiceDied: () => {
      console.info('service died');
    }
  };
  let sessionRestore = new backup.SessionRestore(generalCallbacks);
  async function appendBundles() {
    try {
      let fileData = await backup.getLocalCapabilities();
      console.info('getLocalCapabilities success');
      let restoreApps: Array<string> = [
        "com.example.hiworld",
      ];
      sessionRestore.appendBundles(fileData.fd, restoreApps, (err: BusinessError) => {
        if (err) {
          console.error('appendBundles failed with err: ' + JSON.stringify(err));
        }
        console.info('appendBundles success');
      });
    } catch (error) {
      let err: BusinessError = error as BusinessError;
      console.error('getLocalCapabilities failed with err: ' + JSON.stringify(err));
    }
  }

appendBundles

appendBundles(remoteCapabilitiesFd: number, bundlesToBackup: string[]): Promise<void>

Appends the applications whose data needs to be restored. Currently, the obtained SessionRestore instance can be called only once in the entire restoration process. This API uses a promise to return the result.

NOTE

• During the data restoration, the capability file needs to be verified.
• Therefore, remoteCapabilitiesFd can be obtained by using the getLocalCapabilities API provided by the backup service. You can modify the parameters based on the actual situation of your application. You can also use the JSON file example provided by getLocalCapabilities to generate a capability file.

Required permissions: ohos.permission.BACKUP

System capability: SystemCapability.FileManagement.StorageService.Backup

Parameters

Return value

Error codes

For details about the error codes, see File Management Error Codes.

Example

  import fs from '@ohos.file.fs';
  import { BusinessError } from '@ohos.base';
  let generalCallbacks: backup.GeneralCallbacks = {
    onFileReady: (err: BusinessError, file: backup.File) => {
      if (err) {
        console.error('onFileReady failed with err: ' + JSON.stringify(err));
      }
      console.info('onFileReady success');
      fs.closeSync(file.fd);
    },
    onBundleBegin: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleBegin failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleBegin success');
    },
    onBundleEnd: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleEnd success');
    },
    onAllBundlesEnd: (err: BusinessError) => {
      if (err) {
        console.error('onAllBundlesEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onAllBundlesEnd success');
    },
    onBackupServiceDied: () => {
      console.info('service died');
    }
  };
  let sessionRestore = new backup.SessionRestore(generalCallbacks);
  async function appendBundles() {
    try {
      let fileData = await backup.getLocalCapabilities();
      console.info('getLocalCapabilities success');
      let restoreApps: Array<string> = [
        "com.example.hiworld",
      ];
      await sessionRestore.appendBundles(fileData.fd, restoreApps);
      console.info('appendBundles success');
    } catch (error) {
      let err: BusinessError = error as BusinessError;
      console.error('getLocalCapabilities failed with err: ' + JSON.stringify(err));
    }
  }

getFileHandle

getFileHandle(fileMeta: FileMeta, callback: AsyncCallback<void>): void

Obtains the handle of the shared file from the service. This API uses an asynchronous callback to return the result.

NOTE

• This interface is part of the zero-copy feature, which reduces unnecessary memory copies and increases transmission efficiency. For details about the zero-copy methods, see the zero-copy APIs such as fs.copyFile provided by @ohos.file.fs.
• Before using getFileHandle, you need to obtain a SessionRestore instance and add the applications with data to be restored by using appendBundles.
• You can use onFileReady to obtain the file handle. When file operations are completed at the client, you need to use publishFile to publish the file.
• getFileHandle can be called multiple times based on the number of files to be restored.

Required permissions: ohos.permission.BACKUP

System capability: SystemCapability.FileManagement.StorageService.Backup

Parameters

Error codes

For details about the error codes, see File Management Error Codes.

Example

  import fs from '@ohos.file.fs';
  import { BusinessError } from '@ohos.base';
  let generalCallbacks: backup.GeneralCallbacks = {
    onFileReady: (err: BusinessError, file: backup.File) => {
      if (err) {
        console.error('onFileReady failed with err: ' + JSON.stringify(err));
      }
      console.info('onFileReady success');
      fs.closeSync(file.fd);
    },
    onBundleBegin: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleBegin failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleBegin success');
    },
    onBundleEnd: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleEnd success');
    },
    onAllBundlesEnd: (err: BusinessError) => {
      if (err) {
        console.error('onAllBundlesEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onAllBundlesEnd success');
    },
    onBackupServiceDied: () => {
      console.info('service died');
    }
  };
  let sessionRestore = new backup.SessionRestore(generalCallbacks);
  let fileMeta: backup.FileMeta = {
    bundleName: "com.example.hiworld",
    uri: "test.txt"
  }
  sessionRestore.getFileHandle(fileMeta, (err: BusinessError) => {
    if (err) {
      console.error('getFileHandle failed with err: ' + JSON.stringify(err));
    }
    console.info('getFileHandle success');
  });

getFileHandle

getFileHandle(fileMeta: FileMeta): Promise<void>

Obtains the handle of the shared file from the service. This API uses a promise to return the result.

NOTE

• This interface is part of the zero-copy feature, which reduces unnecessary memory copies and increases transmission efficiency. For details about the zero-copy methods, see the zero-copy APIs such as fs.copyFile provided by @ohos.file.fs.
• Before using getFileHandle, you need to obtain a SessionRestore instance and add the applications with data to be restored by using appendBundles.
• You can use onFileReady to obtain the file handle. When file operations are completed at the client, you need to use publishFile to publish the file.
• getFileHandle can be called multiple times based on the number of files to be restored.

Required permissions: ohos.permission.BACKUP

System capability: SystemCapability.FileManagement.StorageService.Backup

Parameters

Return value

Error codes

For details about the error codes, see File Management Error Codes.

Example

  import fs from '@ohos.file.fs';
  import { BusinessError } from '@ohos.base';
  let generalCallbacks: backup.GeneralCallbacks = {
    onFileReady: (err: BusinessError, file: backup.File) => {
      if (err) {
        console.error('onFileReady failed with err: ' + JSON.stringify(err));
      }
      console.info('onFileReady success');
      fs.closeSync(file.fd);
    },
    onBundleBegin: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleBegin failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleBegin success');
    },
    onBundleEnd: (err: BusinessError, bundleName: string) => {
      if (err) {
        console.error('onBundleEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onBundleEnd success');
    },
    onAllBundlesEnd: (err: BusinessError) => {
      if (err) {
        console.error('onAllBundlesEnd failed with err: ' + JSON.stringify(err));
      }
      console.info('onAllBundlesEnd success');
    },
    onBackupServiceDied: () => {
      console.info('service died');
    }
  };
  let sessionRestore = new backup.SessionRestore(generalCallbacks);
  async function getFileHandle() {
    try {
      let fileMeta: backup.FileMeta = {
        bundleName: "com.example.hiworld",
        uri: "test.txt"
      }
      await sessionRestore.getFileHandle(fileMeta);
      console.info('getFileHandle success');
    } catch (error) {
      let err: BusinessError = error as BusinessError;
      console.error('getFileHandle failed with err: ' + JSON.stringify(err));
    }
  }

publishFile

publishFile(fileMeta: FileMeta, callback: AsyncCallback<void>): void

Publishes FileMeta to the backup service to indicate that the file content is ready. This API uses an asynchronous callback to return the result.

NOTE

• This interface is part of the zero-copy feature, which reduces unnecessary memory copies and increases transmission efficiency. For details about the zero-copy methods, see the zero-copy APIs such as fs.copyFile provided by @ohos.file.fs.
• After the server returns a file handle through onFileReady, the client can copy data to the file corresponding to the file handle provided by the server through zero-copy operations.
• After the copy is complete, you can use publishFile to notify the backup service that the file is ready.

Required permissions: ohos.permission.BACKUP

System capability: SystemCapability.FileManagement.StorageService.Backup

Parameters

Error codes

For details about the error codes, see File Management Error Codes.

Example

  import fs from '@ohos.file.fs';
  import { BusinessError } from '@ohos.base';
  let g_session: backup.SessionRestore;
  function createSessionRestore() {
    let generalCallbacks: backup.GeneralCallbacks = {
      onFileReady: (err: BusinessError, file: backup.File) => {
        if (err) {
          console.error('onFileReady failed with err: ' + JSON.stringify(err));
        }
        console.info('onFileReady success');
        fs.closeSync(file.fd);
        let fileMeta: backup.FileMeta = {
          bundleName: file.bundleName,
          uri: file.uri
        }
        g_session.publishFile(fileMeta, (err: BusinessError) => {
          if (err) {
            console.error('publishFile failed with err: ' + JSON.stringify(err));
          }
          console.info('publishFile success');
        });
      },
      onBundleBegin: (err: BusinessError, bundleName: string) => {
        if (err) {
          console.error('onBundleBegin failed with err: ' + JSON.stringify(err));
        }
        console.info('onBundleBegin success');
      },
      onBundleEnd: (err: BusinessError, bundleName: string) => {
        if (err) {
          console.error('onBundleEnd failed with err: ' + JSON.stringify(err));
        }
        console.info('onBundleEnd success');
      },
      onAllBundlesEnd: (err: BusinessError) => {
        if (err) {
          console.error('onAllBundlesEnd failed with err: ' + JSON.stringify(err));
        }
        console.info('onAllBundlesEnd success');
      },
      onBackupServiceDied: () => {
        console.info('service died');
      }
    };
    let sessionRestore = new backup.SessionRestore(generalCallbacks);
    return sessionRestore;
  }
  g_session = createSessionRestore();

publishFile

publishFile(fileMeta: FileMeta): Promise<void>

Publishes FileMeta to the backup service to indicate that the file content is ready. This API uses a promise to return the result.

NOTE

• This interface is part of the zero-copy feature, which reduces unnecessary memory copies and increases transmission efficiency. For details about the zero-copy methods, see the zero-copy APIs such as fs.copyFile provided by @ohos.file.fs.
• After the server returns a file handle through onFileReady, the client can copy data to the file corresponding to the file handle provided by the server through zero-copy operations.
• After the copy is complete, you can use publishFile to notify the backup service that the file is ready.

Required permissions: ohos.permission.BACKUP

System capability: SystemCapability.FileManagement.StorageService.Backup

Parameters

Return value

Error codes

For details about the error codes, see File Management Error Codes.

Example

  import fs from '@ohos.file.fs';
  import { BusinessError } from '@ohos.base';
  let g_session: backup.SessionRestore;
  async function publishFile(file: backup.FileMeta) {
    let fileMeta: backup.FileMeta = {
      bundleName: file.bundleName,
      uri: file.uri
    }
    await g_session.publishFile(fileMeta);
  }
  function createSessionRestore() {
    let generalCallbacks: backup.GeneralCallbacks = {
      onFileReady: (err: BusinessError, file: backup.File) => {
        if (err) {
          console.error('onFileReady failed with err: ' + JSON.stringify(err));
        }
        console.info('onFileReady success');
        fs.closeSync(file.fd);
        publishFile(file);
        console.info('publishFile success');
      },
      onBundleBegin: (err: BusinessError, bundleName: string) => {
        if (err) {
          console.error('onBundleBegin failed with err: ' + JSON.stringify(err));
        }
        console.info('onBundleBegin success');
      },
      onBundleEnd: (err: BusinessError, bundleName: string) => {
        if (err) {
          console.error('onBundleEnd failed with err: ' + JSON.stringify(err));
        }
        console.info('onBundleEnd success');
      },
      onAllBundlesEnd: (err: BusinessError) => {
        if (err) {
          console.error('onAllBundlesEnd failed with err: ' + JSON.stringify(err));
        }
        console.info('onAllBundlesEnd success');
      },
      onBackupServiceDied: () => {
        console.info('service died');
      }
    };
    let sessionRestore = new backup.SessionRestore(generalCallbacks);
    return sessionRestore;
  }
  g_session = createSessionRestore();

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