harmony 鸿蒙Uploading and Downloading an Application File

2023-06-24
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Uploading and Downloading an Application File

This topic describes how to enable an application to upload an application file to a network server and download a network resource file from a network server to a local application directory.

Uploading an Application File

You can use ohos.request uploadFile() to upload local files. The system service proxy implements the upload.

NOTE

Currently, only the files in the cache/ directories (cacheDir) can be uploaded.

The ohos.permission.INTERNET permission is required for using ohos.request. For details about how to apply for a permission, see Applying for Permissions.

The following example demonstrates how to upload a file in the cache directory of an application to a network server.

// pages/xxx.ets
import common from '@ohos.app.ability.common';
import fs from '@ohos.file.fs';
import request from '@ohos.request';
import { BusinessError } from '@ohos.base';

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

// Create an application file locally.
let file = fs.openSync(cacheDir + '/test.txt', fs.OpenMode.READ_WRITE|fs.OpenMode.CREATE);
fs.writeSync(file.fd, 'upload file test');
fs.closeSync(file);

// Configure the upload task.
let header = new Map<Object, string>();
header.set('key1', 'value1');
header.set('key2', 'value2');
let files: Array<request.File> = [
  { filename: 'test.txt', name: 'test', uri: 'internal://cache/test.txt', type: 'txt' }
]
let data: Array<request.RequestData> = [{ name: 'name', value: 'value' }];
let uploadConfig: request.UploadConfig = {
  url: 'https://xxx',
  header: header,
  method: 'POST',
  files: files,
  data: data
}

// Upload the created application file to the network server.
try {
  request.uploadFile(context, uploadConfig)
    .then((uploadTask: request.UploadTask) => {
      uploadTask.on('complete', (taskStates: Array<request.TaskState>) => {
        for (let i = 0; i < taskStates.length; i++) {
          console.info(`upload complete taskState: ${JSON.stringify(taskStates[i])}`);
        }
      });
    })
    .catch((err: BusinessError) => {
      console.error(`Invoke uploadFile failed, code is ${err.code}, message is ${err.message}`);
    })
} catch (error) {
  let err: BusinessError = error as BusinessError;
  console.error(`Invoke uploadFile failed, code is ${err.code}, message is ${err.message}`);
}

Downloading a Network Resource File to the Application File Directory

You can use ohos.request downloadFile() to download network resource files to a local application directory. You can use the ohos.file.fs APIs to access the downloaded files in the same way as accessing application files. The system service proxy implements the download.

NOTE

Currently, network resource files can be downloaded only to an application file directory.

The ohos.permission.INTERNET permission is required for using ohos.request. For details about how to apply for a permission, see Applying for Permissions.

The following example demonstrates how to download a network resource file to a local application file directory.

// pages/xxx.ets
// Download the network resource file to the local application file directory, and read data from the file.
import common from '@ohos.app.ability.common';
import fs from '@ohos.file.fs';
import request from '@ohos.request';
import { BusinessError } from '@ohos.base';
import buffer from '@ohos.buffer';

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

try {
  request.downloadFile(context, {
    url: 'https://xxxx/xxxx.txt',
    filePath: filesDir + '/xxxx.txt'
  }).then((downloadTask: request.DownloadTask) => {
    downloadTask.on('complete', () => {
      console.info('download complete');
      let file = fs.openSync(filesDir + '/xxxx.txt', fs.OpenMode.READ_WRITE);
      let arrayBuffer = new ArrayBuffer(1024);
      let readLen = fs.readSync(file.fd, arrayBuffer);
      let buf = buffer.from(arrayBuffer, 0, readLen);
      console.info(`The content of file: ${buf.toString()}`);
      fs.closeSync(file);
    })
  }).catch((err: BusinessError) => {
    console.error(`Invoke downloadTask failed, code is ${err.code}, message is ${err.message}`);
  });
} catch (error) {
  let err: BusinessError = error as BusinessError;
  console.error(`Invoke downloadFile failed, code is ${err.code}, message is ${err.message}`);
}