harmony 鸿蒙File Management Development

2022-10-28
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File Management Development

How do I obtain the path of system screenshots?

Applicable to: OpenHarmony 3.2 Beta5 (API version 9)

Solution

The screenshots are stored in /storage/media/100/local/files/Pictures/Screenshots/.

How do I change the permissions on a directory to read/write on a device?

Applicable to: OpenHarmony 3.2 Beta5 (API version 9)

Symptom

When the hdc command is used to send a file to a device, “permission denied” is displayed.

Solution

Run the hdc shell mount -o remount,rw / command to grant the read/write permissions.

What is the best way to create a file if the file to open does not exist?

Applicable to: OpenHarmony 3.2 (API version 9)

Solution

Use fs.open(path: string, mode?: number) with mode set to fs.OpenMode.CREATE. fs.OpenMode.CREATE creates a file if it does not exist.

How do I solve the problem of garbled Chinese characters in a file?

Applicable to: OpenHarmony 3.2 (API version 9)

Solution

After the buffer data of the file content is read, use TextDecoder of @ohos.util to decode the file content.

let filePath = getContext(this).filesDir + "/test0.txt";
let stream = fs.createStreamSync(filePath, "r+");
let buffer = new ArrayBuffer(4096)
let readOut = stream.readSync(buffer);
let textDecoder = util.TextDecoder.create('utf-8', { ignoreBOM: true })
let readString = textDecoder.decodeWithStream(new Uint8Array(buffer), { stream: false });
console.log ("File content read: "+ readString);

Why is an error reported when fs.copyFile is used to copy a datashare:// file opened by fs.open()?

Applicable to: OpenHarmony 3.2 (API version 9)

Solution

fs.copyFile does not support URIs. You can use fs.open() to obtain the URI, obtain the file descriptor (FD) based on the URI, and then use fs.copyFile to copy the file based on the FD.

let file = fs.openSync("datashare://...")
fs.copyFile(file.fd, 'dstPath', 0).then(() => {
  console.info('copyFile success')
}).catch((err) => {
  console.info("copy file failed with error message: " + err.message + ", error code: " + err.code);
})

How do I modify the specified content of a JSON file in the sandbox?

Applicable to: OpenHarmony 3.2 (API version 9)

Solution

Perform the following steps:

Use fs.openSyn to obtain the FD of the JSON file.

import fs from '@ohos.file.fs';  
let sanFile = fs.open(basePath, fs.OpenMode.READ_WRITE|fs.OpenMode.CREATE);
let fd = sanFile.fd;

Use fs.readSync to read the file content.

let content = fs.readSync(basePath);

Modify the file content.

obj.name = 'new name';

Write the JSON file again.

fs.writeSync(file.fd, JSON.stringify(obj));

For more information, see @ohos.file.fs.

What is the actual path corresponding to the file path obtained through the FileAccess module?

Applicable to: OpenHarmony 3.2 (API version 9, stage model)

Solution

The files are stored in the /storage/media/100/local/files directory. The specific file path varies with the file type and source. To obtain the actual file path, run the following command in the /storage/media/100/local/files directory:

-name [filename]

For more information, see Uploading and Downloading an Application File.