Application File Access (ArkTS)

File Operations in ArkUI

Creating and Reading/Writing a File

// pages/xxx.ets
import { fileIo as fs, ReadOptions } from '@kit.CoreFileKit';
import { common } from '@kit.AbilityKit';
import { buffer } from '@kit.ArkTS';

// Get the application file path
let context = getContext(this) as common.UIAbilityContext;
let filesDir = context.filesDir;

function createFile(): void {
  // Create and open the file if it does not exist; open the file if it exists
  let file = fs.openSync(filesDir + '/test.txt', fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
  // Write content to the file
  let writeLen = fs.writeSync(file.fd, "Try to write str.");
  console.info("The length of str is: " + writeLen);
  // Create an ArrayBuffer object with a size of 1024 bytes to store data read from the file
  let arrayBuffer = new ArrayBuffer(1024);
  // Set the offset and length for reading
  let readOptions: ReadOptions = {
    offset: 0,
    length: arrayBuffer.byteLength
  };
  // Read the file content into the ArrayBuffer object and return the actual number of bytes read
  let readLen = fs.readSync(file.fd, arrayBuffer, readOptions);
  // Convert the ArrayBuffer object to a Buffer object and output as a string
  let buf = buffer.from(arrayBuffer, 0, readLen);
  console.info("the content of file: " + buf.toString());
  // Close the file
  fs.closeSync(file);
}

Reading from One File and Writing to Another

// pages/xxx.ets
import { fileIo as fs, ReadOptions, WriteOptions } from '@kit.CoreFileKit';
import { common } from '@kit.AbilityKit';

// Get the application file path
let context = getContext(this) as common.UIAbilityContext;
let filesDir = context.filesDir;

function readWriteFile(): void {
  // Open the source and destination files
  let srcFile = fs.openSync(filesDir + '/test.txt', fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
  let destFile = fs.openSync(filesDir + '/destFile.txt', fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
  // Read content from the source file and write it to the destination file
  let bufSize = 4096;
  let readSize = 0;
  let buf = new ArrayBuffer(bufSize);
  let readOptions: ReadOptions = {
    offset: readSize,
    length: bufSize
  };
  let readLen = fs.readSync(srcFile.fd, buf, readOptions);
  while (readLen > 0) {
    readSize += readLen;
    let writeOptions: WriteOptions = {
      length: readLen
    };
    fs.writeSync(destFile.fd, buf, writeOptions);
    readOptions.offset = readSize;
    readLen = fs.readSync(srcFile.fd, buf, readOptions);
  }
  // Close the files
  fs.closeSync(srcFile);
  fs.closeSync(destFile);
}

Reading/Writing Files Using Streams

// pages/xxx.ets
import { fileIo as fs, ReadOptions } from '@kit.CoreFileKit';
import { common } from '@kit.AbilityKit';

// Get the application file path
let context = getContext(this) as common.UIAbilityContext;
let filesDir = context.filesDir;

async function readWriteFileWithStream(): Promise<void> {
  // Create and open the input file stream
  let inputStream = fs.createStreamSync(filesDir + '/test.txt', 'r+');
  // Create and open the output file stream
  let outputStream = fs.createStreamSync(filesDir + '/destFile.txt', "w+");

  let bufSize = 4096;
  let readSize = 0;
  let buf = new ArrayBuffer(bufSize);
  let readOptions: ReadOptions = {
    offset: readSize,
    length: bufSize
  };
  // Read content from the source file and write it to the destination file using streams
  let readLen = await inputStream.read(buf, readOptions);
  readSize += readLen;
  while (readLen > 0) {
    const writeBuf = readLen < bufSize ? buf.slice(0, readLen) : buf;
    await outputStream.write(writeBuf);
    readOptions.offset = readSize;
    readLen = await inputStream.read(buf, readOptions);
    readSize += readLen;
  }
  // Close the file streams
  inputStream.closeSync();
  outputStream.closeSync();
}

Listing Files

import { fileIo as fs, Filter, ListFileOptions } from '@kit.CoreFileKit';
import { common } from '@kit.AbilityKit';

// Get the application file path
let context = getContext(this) as common.UIAbilityContext;
let filesDir = context.filesDir;

// List files
function getListFile(): void {
  let listFileOption: ListFileOptions = {
    recursion: false,
    listNum: 0,
    filter: {
      suffix: [".png", ".jpg", ".txt"],
      displayName: ["test*"],
      fileSizeOver: 0,
      lastModifiedAfter: new Date(0).getTime()
    }
  };
  let files = fs.listFileSync(filesDir, listFileOption);
  for (let i = 0; i < files.length; i++) {
    console.info(`The name of file: ${files[i]}`);
  }
}