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FileAccess¶

Inherits: RefCounted < Object

Provides methods for file reading and writing operations.

描述¶

This class can be used to permanently store data in the user device's file system and to read from it. This is useful for store game save data or player configuration files.

Here's a sample on how to write and read from a file:

func save(content):
    var file = FileAccess.open("user://save_game.dat", FileAccess.WRITE)
    file.store_string(content)

func load():
    var file = FileAccess.open("user://save_game.dat", FileAccess.READ)
    var content = file.get_as_text()
    return content

public void Save(string content)
{
    using var file = FileAccess.Open("user://save_game.dat", FileAccess.ModeFlags.Write);
    file.StoreString(content);
}

public string Load()
{
    using var file = FileAccess.Open("user://save_game.dat", FileAccess.ModeFlags.Read);
    string content = file.GetAsText();
    return content;
}

In the example above, the file will be saved in the user data folder as specified in the Data paths documentation.

FileAccess will close when it's freed, which happens when it goes out of scope or when it gets assigned with null. close can be used to close it before then explicitly. In C# the reference must be disposed manually, which can be done with the using statement or by calling the Dispose method directly.

Note: To access project resources once exported, it is recommended to use ResourceLoader instead of FileAccess, as some files are converted to engine-specific formats and their original source files might not be present in the exported PCK package.

Note: Files are automatically closed only if the process exits "normally" (such as by clicking the window manager's close button or pressing Alt + F4). If you stop the project execution by pressing F8 while the project is running, the file won't be closed as the game process will be killed. You can work around this by calling flush at regular intervals.

教程¶

属性¶

bool	big_endian

Methods¶

void	close ( )
bool	eof_reached ( ) const
bool	file_exists ( String path ) static
void	flush ( )
int	get_8 ( ) const
int	get_16 ( ) const
int	get_32 ( ) const
int	get_64 ( ) const
String	get_as_text ( bool skip_cr=false ) const
PackedByteArray	get_buffer ( int length ) const
PackedStringArray	get_csv_line ( String delim="," ) const
float	get_double ( ) const
Error	get_error ( ) const
PackedByteArray	get_file_as_bytes ( String path ) static
String	get_file_as_string ( String path ) static
float	get_float ( ) const
bool	get_hidden_attribute ( String file ) static
int	get_length ( ) const
String	get_line ( ) const
String	get_md5 ( String path ) static
int	get_modified_time ( String file ) static
Error	get_open_error ( ) static
String	get_pascal_string ( )
String	get_path ( ) const
String	get_path_absolute ( ) const
int	get_position ( ) const
bool	get_read_only_attribute ( String file ) static
float	get_real ( ) const
String	get_sha256 ( String path ) static
BitField<UnixPermissionFlags>	get_unix_permissions ( String file ) static
Variant	get_var ( bool allow_objects=false ) const
bool	is_open ( ) const
FileAccess	open ( String path, ModeFlags flags ) static
FileAccess	open_compressed ( String path, ModeFlags mode_flags, CompressionMode compression_mode=0 ) static
FileAccess	open_encrypted ( String path, ModeFlags mode_flags, PackedByteArray key ) static
FileAccess	open_encrypted_with_pass ( String path, ModeFlags mode_flags, String pass ) static
void	seek ( int position )
void	seek_end ( int position=0 )
Error	set_hidden_attribute ( String file, bool hidden ) static
Error	set_read_only_attribute ( String file, bool ro ) static
Error	set_unix_permissions ( String file, BitField<UnixPermissionFlags> permissions ) static
void	store_8 ( int value )
void	store_16 ( int value )
void	store_32 ( int value )
void	store_64 ( int value )
void	store_buffer ( PackedByteArray buffer )
void	store_csv_line ( PackedStringArray values, String delim="," )
void	store_double ( float value )
void	store_float ( float value )
void	store_line ( String line )
void	store_pascal_string ( String string )
void	store_real ( float value )
void	store_string ( String string )
void	store_var ( Variant value, bool full_objects=false )

Enumerations¶

enum ModeFlags:

ModeFlags READ = 1

Opens the file for read operations. The cursor is positioned at the beginning of the file.

ModeFlags WRITE = 2

Opens the file for write operations. The file is created if it does not exist, and truncated if it does.

ModeFlags READ_WRITE = 3

Opens the file for read and write operations. Does not truncate the file. The cursor is positioned at the beginning of the file.

ModeFlags WRITE_READ = 7

Opens the file for read and write operations. The file is created if it does not exist, and truncated if it does. The cursor is positioned at the beginning of the file.

enum CompressionMode:

CompressionMode COMPRESSION_FASTLZ = 0

Uses the FastLZ compression method.

CompressionMode COMPRESSION_DEFLATE = 1

Uses the DEFLATE compression method.

CompressionMode COMPRESSION_ZSTD = 2

Uses the Zstandard compression method.

CompressionMode COMPRESSION_GZIP = 3

Uses the gzip compression method.

CompressionMode COMPRESSION_BROTLI = 4

Uses the brotli compression method (only decompression is supported).

flags UnixPermissionFlags:

UnixPermissionFlags UNIX_READ_OWNER = 256

Read for owner bit.

UnixPermissionFlags UNIX_WRITE_OWNER = 128

Write for owner bit.

UnixPermissionFlags UNIX_EXECUTE_OWNER = 64

Execute for owner bit.

UnixPermissionFlags UNIX_READ_GROUP = 32

Read for group bit.

UnixPermissionFlags UNIX_WRITE_GROUP = 16

Write for group bit.

UnixPermissionFlags UNIX_EXECUTE_GROUP = 8

Execute for group bit.

UnixPermissionFlags UNIX_READ_OTHER = 4

Read for other bit.

UnixPermissionFlags UNIX_WRITE_OTHER = 2

Write for other bit.

UnixPermissionFlags UNIX_EXECUTE_OTHER = 1

Execute for other bit.

UnixPermissionFlags UNIX_SET_USER_ID = 2048

Set user id on execution bit.

UnixPermissionFlags UNIX_SET_GROUP_ID = 1024

Set group id on execution bit.

UnixPermissionFlags UNIX_RESTRICTED_DELETE = 512

Restricted deletion (sticky) bit.

Property Descriptions¶

bool big_endian

void set_big_endian ( bool value )
bool is_big_endian ( )

If true, the file is read with big-endian endianness. If false, the file is read with little-endian endianness. If in doubt, leave this to false as most files are written with little-endian endianness.

Note: big_endian is only about the file format, not the CPU type. The CPU endianness doesn't affect the default endianness for files written.

Note: This is always reset to false whenever you open the file. Therefore, you must set big_endian after opening the file, not before.

Method Descriptions¶

void close ( )

Closes the currently opened file and prevents subsequent read/write operations. Use flush to persist the data to disk without closing the file.

Note: FileAccess will automatically close when it's freed, which happens when it goes out of scope or when it gets assigned with null. In C# the reference must be disposed after we are done using it, this can be done with the using statement or calling the Dispose method directly.

bool eof_reached ( ) const

Returns true if the file cursor has already read past the end of the file.

Note: eof_reached() == false cannot be used to check whether there is more data available. To loop while there is more data available, use:

while file.get_position() < file.get_length():
    # Read data

while (file.GetPosition() < file.GetLength())
{
    // Read data
}

bool file_exists ( String path ) static

Returns true if the file exists in the given path.

Note: Many resources types are imported (e.g. textures or sound files), and their source asset will not be included in the exported game, as only the imported version is used. See ResourceLoader.exists for an alternative approach that takes resource remapping into account.

For a non-static, relative equivalent, use DirAccess.file_exists.

void flush ( )

Writes the file's buffer to disk. Flushing is automatically performed when the file is closed. This means you don't need to call flush manually before closing a file. Still, calling flush can be used to ensure the data is safe even if the project crashes instead of being closed gracefully.

Note: Only call flush when you actually need it. Otherwise, it will decrease performance due to constant disk writes.

int get_8 ( ) const

Returns the next 8 bits from the file as an integer. See store_8 for details on what values can be stored and retrieved this way.

int get_16 ( ) const

Returns the next 16 bits from the file as an integer. See store_16 for details on what values can be stored and retrieved this way.

int get_32 ( ) const

Returns the next 32 bits from the file as an integer. See store_32 for details on what values can be stored and retrieved this way.

int get_64 ( ) const

Returns the next 64 bits from the file as an integer. See store_64 for details on what values can be stored and retrieved this way.

String get_as_text ( bool skip_cr=false ) const

Returns the whole file as a String. Text is interpreted as being UTF-8 encoded.

If skip_cr is true, carriage return characters (\r, CR) will be ignored when parsing the UTF-8, so that only line feed characters (\n, LF) represent a new line (Unix convention).

PackedByteArray get_buffer ( int length ) const

Returns next length bytes of the file as a PackedByteArray.

PackedStringArray get_csv_line ( String delim="," ) const

Returns the next value of the file in CSV (Comma-Separated Values) format. You can pass a different delimiter delim to use other than the default "," (comma). This delimiter must be one-character long, and cannot be a double quotation mark.

Text is interpreted as being UTF-8 encoded. Text values must be enclosed in double quotes if they include the delimiter character. Double quotes within a text value can be escaped by doubling their occurrence.

For example, the following CSV lines are valid and will be properly parsed as two strings each:

Alice,"Hello, Bob!"
Bob,Alice! What a surprise!
Alice,"I thought you'd reply with ""Hello, world""."

Note how the second line can omit the enclosing quotes as it does not include the delimiter. However it could very well use quotes, it was only written without for demonstration purposes. The third line must use "" for each quotation mark that needs to be interpreted as such instead of the end of a text value.

float get_double ( ) const

Returns the next 64 bits from the file as a floating-point number.

Error get_error ( ) const

Returns the last error that happened when trying to perform operations. Compare with the ERR_FILE_* constants from Error.

PackedByteArray get_file_as_bytes ( String path ) static

Returns the whole path file contents as a PackedByteArray without any decoding.

String get_file_as_string ( String path ) static

Returns the whole path file contents as a String. Text is interpreted as being UTF-8 encoded.

float get_float ( ) const

Returns the next 32 bits from the file as a floating-point number.

bool get_hidden_attribute ( String file ) static

Returns true, if file hidden attribute is set.

Note: This method is implemented on iOS, BSD, macOS, and Windows.

int get_length ( ) const

Returns the size of the file in bytes.

String get_line ( ) const

Returns the next line of the file as a String.

Text is interpreted as being UTF-8 encoded.

String get_md5 ( String path ) static

Returns an MD5 String representing the file at the given path or an empty String on failure.

int get_modified_time ( String file ) static

Returns the last time the file was modified in Unix timestamp format, or 0 on error. This Unix timestamp can be converted to another format using the Time singleton.

Error get_open_error ( ) static

Returns the result of the last open call in the current thread.

String get_pascal_string ( )

Returns a String saved in Pascal format from the file.

Text is interpreted as being UTF-8 encoded.

String get_path ( ) const

Returns the path as a String for the current open file.

String get_path_absolute ( ) const

Returns the absolute path as a String for the current open file.

int get_position ( ) const

Returns the file cursor's position.

bool get_read_only_attribute ( String file ) static

Returns true, if file read only attribute is set.

Note: This method is implemented on iOS, BSD, macOS, and Windows.

float get_real ( ) const

Returns the next bits from the file as a floating-point number.

String get_sha256 ( String path ) static

Returns a SHA-256 String representing the file at the given path or an empty String on failure.

BitField<UnixPermissionFlags> get_unix_permissions ( String file ) static

Returns file UNIX permissions.

Note: This method is implemented on iOS, Linux/BSD, and macOS.

Variant get_var ( bool allow_objects=false ) const

Returns the next Variant value from the file. If allow_objects is true, decoding objects is allowed.

Internally, this uses the same decoding mechanism as the @GlobalScope.bytes_to_var method.

Warning: Deserialized objects can contain code which gets executed. Do not use this option if the serialized object comes from untrusted sources to avoid potential security threats such as remote code execution.

bool is_open ( ) const

Returns true if the file is currently opened.

FileAccess open ( String path, ModeFlags flags ) static

Creates a new FileAccess object and opens the file for writing or reading, depending on the flags.

Returns null if opening the file failed. You can use get_open_error to check the error that occurred.

FileAccess open_compressed ( String path, ModeFlags mode_flags, CompressionMode compression_mode=0 ) static

Creates a new FileAccess object and opens a compressed file for reading or writing.

Note: open_compressed can only read files that were saved by Godot, not third-party compression formats. See GitHub issue #28999 for a workaround.

Returns null if opening the file failed. You can use get_open_error to check the error that occurred.

FileAccess open_encrypted ( String path, ModeFlags mode_flags, PackedByteArray key ) static

Creates a new FileAccess object and opens an encrypted file in write or read mode. You need to pass a binary key to encrypt/decrypt it.

Note: The provided key must be 32 bytes long.

Returns null if opening the file failed. You can use get_open_error to check the error that occurred.

FileAccess open_encrypted_with_pass ( String path, ModeFlags mode_flags, String pass ) static

Creates a new FileAccess object and opens an encrypted file in write or read mode. You need to pass a password to encrypt/decrypt it.

Returns null if opening the file failed. You can use get_open_error to check the error that occurred.

void seek ( int position )

Changes the file reading/writing cursor to the specified position (in bytes from the beginning of the file).

void seek_end ( int position=0 )

Changes the file reading/writing cursor to the specified position (in bytes from the end of the file).

Note: This is an offset, so you should use negative numbers or the cursor will be at the end of the file.

Error set_hidden_attribute ( String file, bool hidden ) static

Sets file hidden attribute.

Note: This method is implemented on iOS, BSD, macOS, and Windows.

Error set_read_only_attribute ( String file, bool ro ) static

Sets file read only attribute.

Note: This method is implemented on iOS, BSD, macOS, and Windows.

Error set_unix_permissions ( String file, BitField<UnixPermissionFlags> permissions ) static

Sets file UNIX permissions.

Note: This method is implemented on iOS, Linux/BSD, and macOS.

void store_8 ( int value )

Stores an integer as 8 bits in the file.

Note: The value should lie in the interval [0, 255]. Any other value will overflow and wrap around.

To store a signed integer, use store_64, or convert it manually (see store_16 for an example).

void store_16 ( int value )

Stores an integer as 16 bits in the file.

Note: The value should lie in the interval [0, 2^16 - 1]. Any other value will overflow and wrap around.

To store a signed integer, use store_64 or store a signed integer from the interval [-2^15, 2^15 - 1] (i.e. keeping one bit for the signedness) and compute its sign manually when reading. For example:

const MAX_15B = 1 << 15
const MAX_16B = 1 << 16

func unsigned16_to_signed(unsigned):
    return (unsigned + MAX_15B) % MAX_16B - MAX_15B

func _ready():
    var f = FileAccess.open("user://file.dat", FileAccess.WRITE_READ)
    f.store_16(-42) # This wraps around and stores 65494 (2^16 - 42).
    f.store_16(121) # In bounds, will store 121.
    f.seek(0) # Go back to start to read the stored value.
    var read1 = f.get_16() # 65494
    var read2 = f.get_16() # 121
    var converted1 = unsigned16_to_signed(read1) # -42
    var converted2 = unsigned16_to_signed(read2) # 121

public override void _Ready()
{
    using var f = FileAccess.Open("user://file.dat", FileAccess.ModeFlags.WriteRead);
    f.Store16(unchecked((ushort)-42)); // This wraps around and stores 65494 (2^16 - 42).
    f.Store16(121); // In bounds, will store 121.
    f.Seek(0); // Go back to start to read the stored value.
    ushort read1 = f.Get16(); // 65494
    ushort read2 = f.Get16(); // 121
    short converted1 = (short)read1; // -42
    short converted2 = (short)read2; // 121
}

void store_32 ( int value )

Stores an integer as 32 bits in the file.

Note: The value should lie in the interval [0, 2^32 - 1]. Any other value will overflow and wrap around.

To store a signed integer, use store_64, or convert it manually (see store_16 for an example).

void store_64 ( int value )

Stores an integer as 64 bits in the file.

Note: The value must lie in the interval [-2^63, 2^63 - 1] (i.e. be a valid int value).

void store_buffer ( PackedByteArray buffer )

Stores the given array of bytes in the file.

void store_csv_line ( PackedStringArray values, String delim="," )

Store the given PackedStringArray in the file as a line formatted in the CSV (Comma-Separated Values) format. You can pass a different delimiter delim to use other than the default "," (comma). This delimiter must be one-character long.

Text will be encoded as UTF-8.

void store_double ( float value )

Stores a floating-point number as 64 bits in the file.

void store_float ( float value )

Stores a floating-point number as 32 bits in the file.

void store_line ( String line )

Appends line to the file followed by a line return character (\n), encoding the text as UTF-8.

void store_pascal_string ( String string )

Stores the given String as a line in the file in Pascal format (i.e. also store the length of the string).

Text will be encoded as UTF-8.

void store_real ( float value )

Stores a floating-point number in the file.

void store_string ( String string )

Appends string to the file without a line return, encoding the text as UTF-8.

Note: This method is intended to be used to write text files. The string is stored as a UTF-8 encoded buffer without string length or terminating zero, which means that it can't be loaded back easily. If you want to store a retrievable string in a binary file, consider using store_pascal_string instead. For retrieving strings from a text file, you can use get_buffer(length).get_string_from_utf8() (if you know the length) or get_as_text.

void store_var ( Variant value, bool full_objects=false )

Stores any Variant value in the file. If full_objects is true, encoding objects is allowed (and can potentially include code).

Internally, this uses the same encoding mechanism as the @GlobalScope.var_to_bytes method.

Note: Not all properties are included. Only properties that are configured with the @GlobalScope.PROPERTY_USAGE_STORAGE flag set will be serialized. You can add a new usage flag to a property by overriding the Object._get_property_list method in your class. You can also check how property usage is configured by calling Object._get_property_list. See PropertyUsageFlags for the possible usage flags.