# FileSystemManager.read(Object object)

Start from base library version 2.16.1. Please remaining backward compatible.

with Promise style call: Not supported

Mini Program plugin: Support, need to Mini Program base library version no less than 2.19.2

Read Files

# parameter

# Object object

attribute type Default values Required Introductions
fd string yes File descriptor. fd adopt FileSystemManager.open or FileSystemManager.openSync Interface acquisition
arrayBuffer ArrayBuffer yes The buffer to which the data is written must be ArrayBuffer Example
offset number 0 no Write offset in buffer, default 0
length number 0 no Number of bytes to read from the file, default 0
position number no The starting position of a file read, such as no upload or upload Null, it is read from the position of the current file pointer. if position Is a positive integer, the file pointer position remains the same and is converted from the position Read the file.
success function no Interface calls the successful callback function
fail function no Interface calls failed callback functions
complete function no Callback function at the end of an interface call (both successful and unsuccessful calls are executed)

# object.success callback

# parameter
# Object res
attribute type Introductions
bytesRead number Number of bytes actually read
arrayBuffer ArrayBuffer Object that is written to the buffer, that is, the arrayBuffer

# object.fail callback

# parameter
# Object res
attribute type Introductions
errMsg string Error message

res.errMsg Legal value

value Introductions Minimum version
bad file descriptor Invalid file descriptor
fail permission denied Specified fd Path not read
fail the value of "offset" is out of range Incoming offset illegal
fail the value of "length" is out of range Incoming length illegal
fail sdcard not mounted android sdcard Mount failure
bad file descriptor Invalid file descriptor

# sample code

const fs = wx.getFileSystemManager()
const ab = new ArrayBuffer(1024)
// Open the file
  filePath: `${wx.env.USER_DATA_PATH}/hello.txt`, 
  flag: 'a+',
  success(res) {
    // Read file to ArrayBuffer in
      fd: res.fd,
      arrayBuffer: AB,
      length: 10,
      success(res) {