FileSystemManager.readFile

Introduction

Reads the contents of a local file. The maximum file size limit is 100MB.

Usage Restrictions

Supported in basic library version 3.0.0 or higher.

Parameters

Object object

Attribute	Type	Default	Required	Description
filePath	string		Yes	The path of the file to be read (if you are reading a directory within the applet, such as the images in the images directory under the root directory, you can pass "images/xx.png")
encoding	string		No	Specifies the character encoding of the file to be read. If encoding is not provided, the file's binary content is read as an ArrayBuffer. Valid values: 1. ascii 2. base64 3. binary 4. hex 5. ucs2, read in little-endian 6. ucs-2, read in little-endian 7. utf16le, read in little-endian 8. utf-16le, read in little-endian 9. utf-8 10. utf8 11. latin1
length	number		No	Specifies the length of the file to be read. If not specified, the file is read until the end. Valid range: [1, fileLength]. Unit: byte
position	number		No	Reads from the specified position in the file. If not specified, reading starts from the beginning of the file. The range of the read should be a left-closed right-open interval [position, position+length). Valid range: [0, fileLength - 1]. Unit: byte
success	function		No	Callback function called when the interface is successfully invoked.
fail	function		No	Callback function called when the interface fails to be invoked.
complete	function		No	Callback function called when the interface invocation ends (executed regardless of success or failure).

object.success

Callback Function

Parameters

Object res

Attribute	Type	Description
data	string/ArrayBuffer	File content
success	string	true - success

object.fail Callback Function

Parameters

Object res

Attribute	Type	Description
errMsg	string	Error message
success	string	false - failure

errMsg Description

Error Message	Description
parameter error: F10001	Invalid parameters
fail sdcard not mounted: F10002	Android sdcard mounting fail
fail no such file or directory: F10007 ${filePath}	Directory of filePath does not exist
native buffer exceeds size limit: F10008	File size exceeds limit (100MB)
the named is ${encoding} charset is not supported!	Current character encoding is not supported

Sample Code

// pages/index/index.js
Page({
  readFile() {
    const fs = dlt.getFileSystemManager();
    fs.readFile({
      filePath: `${dlt.env.USER_DATA_PATH}/hello.txt`,
      encoding: 'utf8',
      position: 0,
      success(res) {
        console.log(res.data);
      },
      fail(res) {
        console.error(res);
      },
    });
  },
});