Object built-in object

ObjectFile

File operation object, used for binary file reading and writing

The file operation object is used to operate binary files. You can usefsModule to open and create files:

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var f = fs.openFile('test.txt');

inheritance relationship

member properties

name

String, query the current file name

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readonly String File.name;

fd

Integer, query the current file descriptor

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readonly Integer File.fd;

Integer, queryStreamThe corresponding file descriptor value, implemented by subclasses

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readonly Integer File.fd;

member function

chmod

Query the access permissions of the current file. Windows does not support this method.

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File.chmod(Integer mode) async;

Call parameters:

  • mode: Integer, specifies the set access permissions

seek

Move the current file operation location

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File.seek(Long offset, Integer whence = fs.SEEK_SET);

Call parameters:

  • offset: Long, specify the new location
  • whence: Integer, specifies the position reference, allowed values ​​are: SEEK_SET, SEEK_CUR, SEEK_END

tell

Query the current position of the stream

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Long File.tell();

Return results:

  • Long, returns the current position of the stream

rewind

Move the current position to the beginning of the stream

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File.rewind();

size

Query stream size

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Long File.size();

Return results:

  • Long, returns the stream size

readAll

Read all remaining data from the stream

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Buffer File.readAll() async;

Return results:

  • Buffer, returns the data read from the stream. If there is no data to read or the connection is interrupted, null is returned.

truncate

Modify the file size. If the new size is smaller than the original size, the file will be truncated.

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File.truncate(Long bytes) async;

Call parameters:

  • bytes: Long, new file size

eof

Query whether the file reaches the end

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Boolean File.eof();

Return results:

  • Boolean, returns True to indicate the end

stat

Query basic information of the current file

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Stat File.stat() async;

Return results:

  • Stat, returnStatObject description file information

read

Read data of specified size from the stream

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Buffer File.read(Integer bytes = -1) async;

Call parameters:

  • bytes: Integer, specifies the amount of data to be read. The default is to read data blocks of random size. The size of the data read depends on the device.

Return results:

  • Buffer, returns the data read from the stream. If there is no data to read or the connection is interrupted, null is returned.

write

Write the given data to the stream

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File.write(Buffer data) async;

Call parameters:

  • data:Buffer, given the data to be written

flush

Write file buffer contents to physical device

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File.flush() async;

close

Close the current stream object

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File.close() async;

copyTo

Copy stream data to target stream

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Long File.copyTo(Stream stm, Long bytes = -1) async;

Call parameters:

  • stm:Stream, target stream object
  • bytes: Long, number of bytes copied

Return results:

  • Long, returns the number of bytes copied

toString

Returns the string representation of the object. Generally, "[Native Object]" is returned. The object can be re-implemented according to its own characteristics.

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String File.toString();

Return results:

  • String, returns the string representation of the object

toJSON

Returns a JSON format representation of the object, generally returning a collection of readable properties defined by the object.

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Value File.toJSON(String key = "");

Call parameters:

  • key: String, not used

Return results:

  • Value, returns a value containing JSON serializable