1# @ohos.file.hash (File Hash Processing) 2 3The **fileHash** module implements hash processing on files. 4 5> **NOTE** 6> 7> - 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. 8> - The APIs of this module support processing of error codes. For details, see [File Management Error Codes](../errorcodes/errorcode-filemanagement.md). 9 10## Modules to Import 11 12```js 13import Hash from '@ohos.file.hash'; 14``` 15 16## Guidelines 17 18Before using the APIs provided by this module to perform operations on a file or directory, obtain the path of the file or directory in the application sandbox as follows: 19 20**Stage Model** 21 22 ```js 23import UIAbility from '@ohos.app.ability.UIAbility'; 24 25export default class EntryAbility extends UIAbility { 26 onWindowStageCreate(windowStage) { 27 let context = this.context; 28 let pathDir = context.filesDir; 29 } 30} 31 ``` 32 33**FA Model** 34 35 ```js 36 import featureAbility from '@ohos.ability.featureAbility'; 37 38 let context = featureAbility.getContext(); 39 context.getFilesDir().then((data) => { 40 let pathDir = data; 41 }) 42 ``` 43 44For details about how to obtain the FA model context, see [Context](js-apis-inner-app-context.md#context). 45 46## Hash.hash 47 48hash(path: string, algorithm: string): Promise<string> 49 50Calculates a hash value for a file. This API uses a promise to return the result. 51 52**System capability**: SystemCapability.FileManagement.File.FileIO 53 54**Parameters** 55 56| Name | Type | Mandatory| Description | 57| --------- | ------ | ---- | ------------------------------------------------------------ | 58| path | string | Yes | Path of the file in the application sandbox. | 59| algorithm | string | Yes | Algorithm used to calculate the hash value. The value can be **md5**, **sha1**, or **sha256**. **sha256** is recommended for security purposes.| 60 61**Return value** 62 63 | Type | Description | 64 | --------------------- | -------------------------- | 65 | Promise<string> | Promise used to return the hash value. The hash value is a hexadecimal string consisting of digits and uppercase letters.| 66 67**Example** 68 69 ```js 70 let filePath = pathDir + "/test.txt"; 71 Hash.hash(filePath, "sha256").then((str) => { 72 console.info("calculate file hash succeed:" + str); 73 }).catch((err) => { 74 console.info("calculate file hash failed with error message: " + err.message + ", error code: " + err.code); 75 }); 76 ``` 77 78## Hash.hash 79 80hash(path: string, algorithm: string, callback: AsyncCallback<string>): void 81 82Calculates a hash value for a file. This API uses an asynchronous callback to return the result. 83 84**System capability**: SystemCapability.FileManagement.File.FileIO 85 86**Parameters** 87 88| Name | Type | Mandatory| Description | 89| --------- | --------------------------- | ---- | ------------------------------------------------------------ | 90| path | string | Yes | Path of the file in the application sandbox. | 91| algorithm | string | Yes | Algorithm used to calculate the hash value. The value can be **md5**, **sha1**, or **sha256**. **sha256** is recommended for security purposes.| 92| callback | AsyncCallback<string> | Yes | Callback used to return the hash value obtained. The hash value is a hexadecimal string consisting of digits and uppercase letters.| 93 94**Example** 95 ```js 96 let filePath = pathDir + "/test.txt"; 97 Hash.hash(filePath, "sha256", (err, str) => { 98 if (err) { 99 console.info("calculate file hash failed with error message: " + err.message + ", error code: " + err.code); 100 } else { 101 console.info("calculate file hash succeed:" + str); 102 } 103 }); 104 ``` 105