class FileStream
package openfl.filesystem
extends EventDispatcher
implements IDataOutput, IDataInput
Available on AIR, Android, HashLink, Linux, Neko, Windows, iOS, macOS
A FileStream object is used to read and write files. Files can be opened synchronously by calling the open() method or asynchronously by calling the openAsync() method.
The advantage of opening files asynchronously is that other code can execute while Adobe AIR runs read and write processes in the background. When opened asynchronously, progress events are dispatched as operations proceed.
A File object that is opened synchronously behaves much like a ByteArray object; a file opened asynchronously behaves much like a Socket or URLStream object. When a File object is opened synchronously, the caller pauses while the requested data is read from or written to the underlying file. When opened asynchronously, any data written to the stream is immediately buffered and later written to the file.
Whether reading from a file synchronously or asynchronously, the actual read methods are synchronous. In both cases they read from data that is currently "available." The difference is that when reading synchronously all of the data is available at all times, and when reading asynchronously data becomes available gradually as the data streams into a read buffer. Either way, the data that can be synchronously read at the current moment is represented by the bytesAvailable property.
An application that is processing asynchronous input typically registers for progress events and consumes the data as it becomes available by calling read methods. Alternatively, an application can simply wait until all of the data is available by registering for the complete event and processing the entire data set when the complete event is dispatched.
See also:
Constructor
Variables
read onlybytesAvailable:Int
Returns the number of bytes of data available for reading in the input buffer. User code must call bytesAvailable to ensure that sufficient data is available before trying to read it with one of the read methods.
See also:
endian:Endian
The byte order for the data, either the BIG_ENDIAN or LITTLE_ENDIAN constant from the Endian class.
read onlyisWriting:Bool = false
The isWriting property returns a bool used to identify the write state of asynchronous Update, Append, or Write streams. If isWrite is true, data is actively being written from the buffer.
objectEncoding:ObjectEncoding
Specifies whether the HXSF, JSON, AMF3 or AMF0 format is used when writing or reading binary data by using the readObject() or writeObject() method.
The value is a constant from the ObjectEncoding class. By default, on non-AIR platforms, the HXSF format is used. For AIR the default format is AMF3. If you would like to use AMF and AMF3 on non-AIR platforms, you must also include the format dependency in your project from haxelib.
position:UInt
The current position in the file.
This value is modified in any of the following ways:
- When you set the property explicitly
- When reading from the FileStream object (by using one of the read methods)
- When writing to the FileStream object
The position is defined as a Number (instead of uint) in order to support files larger than 232 bytes in length. The value of this property is always a whole number less than 253. If you set this value to a number with a fractional component, the value is rounded down to the nearest integer.
When reading a file asyncronously, if you set the position property, the application begins filling the read buffer with the data starting at the specified position, and the bytesAvailable property may be set to 0. Wait for a complete event before using a read method to read data; or wait for a progress event and check the bytesAvailable property before using a read method.
See also:
readAhead:Float = Math.POSITIVE_INFINITY
The minimum amount of data to read from disk when reading files asynchronously.
This property specifies how much data an asynchronous stream attempts to read beyond the current position. Data is read in blocks based on the file system page size. Thus if you set readAhead to 9,000 on a computer system with an 8KB (8192 byte) page size, the runtime reads ahead 2 blocks, or 16384 bytes at a time. The default value of this property is infinity: by default a file that is opened to read asynchronously reads as far as the end of the file.
Reading data from the read buffer does not change the value of the readAhead property. When you read data from the buffer, new data is read in to refill the read buffer.
The readAhead property has no effect on a file that is opened synchronously.
As data is read in asynchronously, the FileStream object dispatches progress events. In the event handler method for the progress event, check to see that the required number of bytes is available (by checking the bytesAvailable property), and then read the data from the read buffer by using a read method.
Methods
close():Void
Closes the FileStream object.
You cannot read or write any data after you call the close() method. If the file was opened asynchronously (the FileStream object used the openAsync() method to open the file), calling the close() method causes the object to dispatch the close event.
Closing the application automatically closes all files associated with FileStream objects in the application. However, it is best to register for a closed event on all FileStream objects opened asynchronously that have pending data to write, before closing the application (to ensure that data is written).
You can reuse the FileStream object by calling the open() or the openAsync() method. This closes any file associated with the FileStream object, but the object does not dispatch the close event.
For a FileStream object opened asynchronously (by using the openAsync() method), even if you call the close() event for a FileStream object and delete properties and variables that reference the object, the FileStream object is not garbage collected as long as there are pending operations and event handlers are registered for their completion. In particular, an otherwise unreferenced FileStream object persists as long as any of the following are still possible:
For file reading operations, the end of the file has not been reached (and the complete event has not been dispatched). Output data is still available to written, and output-related events (such as the outputProgress event or the ioError event) have registered event listeners.
Events:
close | The file, which was opened asynchronously, is closed. |
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open(file:File, fileMode:FileMode):Void
Opens the FileStream object synchronously, pointing to the file specified by the file parameter.
If the FileStream object is already open, calling the method closes the file before opening and no further events (including close) are delivered for the previously opened file.
On systems that support file locking, a file opened in "write" or "update" mode (FileMode.WRITE or FileMode.UPDATE) is not readable until it is closed.
Once you are done performing operations on the file, call the close() method of the FileStream object. Some operating systems limit the number of concurrently open files.
Parameters:
file | The File object specifying the file to open. |
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fileMode | A string from the FileMode class that defines the capabilities of the FileStream, such as the ability to read from or write to the file. |
Throws:
IOError | The file does not exist; you do not have adequate permissions to open the file; you are opening a file for read access, and you do not have read permissions; or you are opening a file for write access, and you do not have write permissions. |
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SecurityError | The file location is in the application directory, and the fileMode parameter is set to "append", "update", or "write" mode. |
See also:
openAsync(file:File, fileMode:FileMode):Void
Opens the FileStream object asynchronously, pointing to the file specified by the file parameter.
If the FileStream object is already open, calling the method closes the file before opening and no further events (including close) are delivered for the previously opened file.
If the fileMode parameter is set to FileMode.READ or FileMode.UPDATE, AIR reads data into the input buffer as soon as the file is opened, and progress and open events are dispatched as the data is read to the input buffer.
On systems that support file locking, a file opened in "write" or "update" mode (FileMode.WRITE or FileMode.UPDATE) is not readable until it is closed.
Once you are done performing operations on the file, call the close() method of the FileStream object. Some operating systems limit the number of concurrently open files.
Parameters:
file | The File object specifying the file to open. |
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A | string from the FileMode class that defines the capabilities of the FileStream, such as the ability to read from or write to the file. |
Throws:
SecurityError | The file location is in the application directory, and the fileMode parameter is set to "append", "update", or "write" mode. |
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Events:
ioError | The file does not exist; you do not have adequate permissions to open the file; you are opening a file for read access, and you do not have read permissions; or you are opening a file for write access, and you do not have write permissions. |
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progress | Dispatched as data is read to the input buffer. (The file must be opened with the fileMode parameter set to FileMode.READ or FileMode.UPDATE.) |
complete | The file data has been read to the input buffer. (The file must be opened with the fileMode parameter set to FileMode.READ or FileMode.UPDATE.) |
See also:
readBoolean():Bool
Reads a Boolean value from the file stream, byte stream, or byte array. A single byte is read and true is returned if the byte is nonzero, false otherwise.
Returns:
A Boolean value, true if the byte is nonzero, false otherwise.
Throws:
IOError | The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be read (for example, because the file is missing). |
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EOFError | The position specfied for reading data exceeds the number of bytes available (specified by the bytesAvailable property). |
Events:
ioError | The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method). |
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readByte():Int
Reads a signed byte from the file stream, byte stream, or byte array.
Returns:
The returned value is in the range -128 to 127.
Throws:
IOError | The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be read (for example, because the file is missing). |
|---|---|
EOFError | The position specfied for reading data exceeds the number of bytes available (specified by the bytesAvailable property). |
Events:
ioError | The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method). |
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readBytes(bytes:ByteArray, offset:UInt = 0, length:UInt = 0):Void
Reads the number of data bytes, specified by the length parameter, from the file stream, byte stream, or byte array. The bytes are read into the ByteArray objected specified by the bytes parameter, starting at the position specified by offset.
Parameters:
bytes | |
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offset | |
length |
Throws:
IOError | The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be read (for example, because the file is missing). |
|---|---|
EOFError | The position specfied for reading data exceeds the number of bytes available (specified by the bytesAvailable property). |
Events:
ioError | The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method). |
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readDouble():Float
Reads an IEEE 754 double-precision floating point number from the file stream, byte stream, or byte array.
Returns:
An IEEE 754 double-precision floating point number
Throws:
IOError | The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be read (for example, because the file is missing). |
|---|---|
EOFError | The position specfied for reading data exceeds the number of bytes available (specified by the bytesAvailable property). |
Events:
ioError | The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method). |
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readFloat():Float
Reads an IEEE 754 single-precision floating point number from the file stream, byte stream, or byte array.
Returns:
An IEEE 754 single-precision floating point number.
Throws:
IOError | The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be read (for example, because the file is missing). |
|---|---|
EOFError | The position specfied for reading data exceeds the number of bytes available (specified by the bytesAvailable property). |
Events:
ioError | The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method). |
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readInt():Int
Reads a signed 32-bit integer from the file stream, byte stream, or byte array.
Returns:
The returned value is in the range -2147483648 to 2147483647.
Throws:
IOError | The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be read (for example, because the file is missing). |
|---|---|
EOFError | The position specfied for reading data exceeds the number of bytes available (specified by the bytesAvailable property). |
Events:
ioError | The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method). |
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readMultiByte(length:Int, charSet:String):String
Reads a multibyte string of specified length from the file stream, byte stream, or byte array using the specified character set.
Parameters:
length | The number of bytes from the byte stream to read. |
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charSet | The string denoting the character set to use to interpret the bytes. Possible character set strings include "shift-jis", "cn-gb", "iso-8859-1", and others. * |
Returns:
UTF-8 encoded string.
Throws:
IOError | The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be read (for example, because the file is missing). |
|---|---|
EOFError | The position specfied for reading data exceeds the number of bytes available (specified by the bytesAvailable property). |
Events:
ioError | The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method). |
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readObject():Dynamic
Reads an object from the file stream, byte stream, or byte array, encoded in AMF serialized format.
Returns:
The deserialized object
Throws:
IOError | The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be read (for example, because the file is missing). |
|---|---|
EOFError | The position specfied for reading data exceeds the number of bytes available (specified by the bytesAvailable property). |
Events:
ioError | The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method). |
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readShort():Int
Reads a signed 16-bit integer from the file stream, byte stream, or byte array.
Returns:
The returned value is in the range -32768 to 32767.
Throws:
IOError | The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be read (for example, because the file is missing). |
|---|---|
EOFError | The position specfied for reading data exceeds the number of bytes available (specified by the bytesAvailable property). |
Events:
ioError | The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method). |
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readUTF():String
Reads a UTF-8 string from the file stream, byte stream, or byte array. The string is assumed to be prefixed with an unsigned short indicating the length in bytes.
This method is similar to the readUTF() method in the Java® IDataInput interface.
Returns:
A UTF-8 string produced by the byte representation of characters.
Throws:
IOError | The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be read (for example, because the file is missing). |
|---|---|
EOFError | The position specfied for reading data exceeds the number of bytes available (specified by the bytesAvailable property). |
Events:
ioError | The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method). |
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readUTFBytes(length:Int):String
Reads a sequence of UTF-8 bytes from the byte stream or byte array and returns a string.
Parameters:
length | The number of bytes to read. |
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Returns:
A UTF-8 string produced by the byte representation of characters of the specified length.
Throws:
IOError | The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be read (for example, because the file is missing). |
|---|---|
EOFError | The position specfied for reading data exceeds the number of bytes available (specified by the bytesAvailable property). |
Events:
ioError | The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method). |
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readUnsignedByte():UInt
Reads an unsigned byte from the file stream, byte stream, or byte array.
Returns:
The returned value is in the range 0 to 255.
Throws:
IOError | The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be read (for example, because the file is missing). |
|---|---|
EOFError | The position specfied for reading data exceeds the number of bytes available (specified by the bytesAvailable property). |
Events:
ioError | The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method). |
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readUnsignedInt():UInt
Reads an unsigned 32-bit integer from the file stream, byte stream, or byte array.
Returns:
The returned value is in the range 0 to 4294967295.
Throws:
IOError | The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be read (for example, because the file is missing). |
|---|---|
EOFError | The position specfied for reading data exceeds the number of bytes available (specified by the bytesAvailable property). |
Events:
ioError | The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method). |
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readUnsignedShort():UInt
Reads an unsigned 16-bit integer from the file stream, byte stream, or byte array.
Throws:
IOError | The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be read (for example, because the file is missing). |
|---|---|
EOFError | The position specfied for reading data exceeds the number of bytes available (specified by the bytesAvailable property). |
Events:
ioError | The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method). |
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truncate():Void
Truncates the file at the position specified by the position property of the FileStream object.
Bytes from the position specified by the position property to the end of the file are deleted. The file must be open for writing.
Throws:
IllegalOperationError | The file is not open for writing. |
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writeBoolean(value:Bool):Void
Writes a Boolean value. A single byte is written according to the value parameter, either 1 if true or 0 if false.
Parameters:
value | A Boolean value determining which byte is written. If the parameter is true, 1 is written; if false, 0 is written. |
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Throws:
The | file has not been opened; the file has been opened, but it was not opened with write capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be written (for example, because the file is missing). |
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Events:
ioError | You cannot write to the file (for example, because the file is missing). This event is dispatched only for files that have been opened for asynchronous operations (by using the openAsync() method). |
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writeByte(value:Int):Void
Writes a byte. The low 8 bits of the parameter are used; the high 24 bits are ignored.
Parameters:
value | A byte value as an integer. |
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Throws:
The | file has not been opened; the file has been opened, but it was not opened with write capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be written (for example, because the file is missing). |
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Events:
ioError | You cannot write to the file (for example, because the file is missing). This event is dispatched only for files that have been opened for asynchronous operations (by using the openAsync() method). |
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writeBytes(bytes:ByteArray, offset:Int = 0, length:Int = 0):Void
Writes a sequence of bytes from the specified byte array, bytes, starting at the byte specified by offset (using a zero-based index) with a length specified by length, into the file stream, byte stream, or byte array.
If the length parameter is omitted, the default length of 0 is used and the entire buffer starting at offset is written. If the offset parameter is also omitted, the entire buffer is written.
If the offset or length parameter is out of range, they are clamped to the beginning and end of the bytes array.
Parameters:
bytes | The byte array to write. |
|---|---|
offset | A zero-based index specifying the position into the array to begin writing. |
length | An unsigned integer specifying how far into the buffer to write. |
Throws:
The | file has not been opened; the file has been opened, but it was not opened with write capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be written (for example, because the file is missing). |
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Events:
ioError | You cannot write to the file (for example, because the file is missing). This event is dispatched only for files that have been opened for asynchronous operations (by using the openAsync() method). |
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writeDouble(value:Float):Void
Writes an IEEE 754 double-precision (64-bit) floating point number.
Parameters:
value | A double-precision (64-bit) floating point number. |
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Throws:
The | file has not been opened; the file has been opened, but it was not opened with write capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be written (for example, because the file is missing). |
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Events:
ioError | You cannot write to the file (for example, because the file is missing). This event is dispatched only for files that have been opened for asynchronous operations (by using the openAsync() method). |
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writeFloat(value:Float):Void
Writes an IEEE 754 single-precision (32-bit) floating point number.
Parameters:
A | single-precision (32-bit) floating point number. |
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Throws:
The | file has not been opened; the file has been opened, but it was not opened with write capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be written (for example, because the file is missing). |
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Events:
ioError | You cannot write to the file (for example, because the file is missing). This event is dispatched only for files that have been opened for asynchronous operations (by using the openAsync() method). |
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writeInt(value:Int):Void
Writes a 32-bit signed integer.
Parameters:
value | A byte value as a signed integer |
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Throws:
The | file has not been opened; the file has been opened, but it was not opened with write capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be written (for example, because the file is missing). |
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Events:
ioError | You cannot write to the file (for example, because the file is missing). This event is dispatched only for files that have been opened for asynchronous operations (by using the openAsync() method). |
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writeMultiByte(value:String, charSet:String):Void
Writes a multibyte string to the file stream, byte stream, or byte array, using the specified character set.
Parameters:
value | The string value to be written. |
|---|---|
charSet | The string denoting the character set to use. Possible character set strings include "shift-jis", "cn-gb", "iso-8859-1", and others |
Throws:
The | file has not been opened; the file has been opened, but it was not opened with write capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be written (for example, because the file is missing). |
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Events:
ioError | You cannot write to the file (for example, because the file is missing). This event is dispatched only for files that have been opened for asynchronous operations (by using the openAsync() method). |
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writeObject(object:Dynamic):Void
Writes an object to the file stream, byte stream, or byte array, in AMF, HXSF, or JSON serialized format. The format library from haxelib is required to enable AMF on non-AIR targets.
Parameters:
object | The object to be serialized. |
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Throws:
The | file has not been opened; the file has been opened, but it was not opened with write capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be written (for example, because the file is missing). |
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Events:
ioError | You cannot write to the file (for example, because the file is missing). This event is dispatched only for files that have been opened for asynchronous operations (by using the openAsync() method). |
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writeShort(value:Int):Void
Writes a 16-bit integer. The low 16 bits of the parameter are used; the high 16 bits are ignored.
Parameters:
value | A byte value as an integer. |
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Throws:
The | file has not been opened; the file has been opened, but it was not opened with write capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be written (for example, because the file is missing). |
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Events:
ioError | You cannot write to the file (for example, because the file is missing). This event is dispatched only for files that have been opened for asynchronous operations (by using the openAsync() method). |
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writeUTF(value:String):Void
Writes a UTF-8 string to the file stream, byte stream, or byte array. The length of the UTF-8 string in bytes is written first, as a 16-bit integer, followed by the bytes representing the characters of the string.
Parameters:
value | The string value to be written. |
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Throws:
RangeError | — If the length of the string is larger than 65535. |
|---|---|
The | file has not been opened; the file has been opened, but it was not opened with write capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be written (for example, because the file is missing). |
Events:
ioError | You cannot write to the file (for example, because the file is missing). This event is dispatched only for files that have been opened for asynchronous operations (by using the openAsync() method). |
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writeUTFBytes(value:String):Void
Writes a UTF-8 string. Similar to writeUTF(), but does not prefix the string with a 16-bit length integer.
Parameters:
value | The string value to be written. |
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Throws:
The | file has not been opened; the file has been opened, but it was not opened with write capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be written (for example, because the file is missing). |
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Events:
ioError | You cannot write to the file (for example, because the file is missing). This event is dispatched only for files that have been opened for asynchronous operations (by using the openAsync() method). |
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writeUnsignedInt(value:UInt):Void
Writes a 32-bit unsigned integer.
Parameters:
value | A byte value as an unsigned integer. |
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Throws:
The | file has not been opened; the file has been opened, but it was not opened with write capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be written (for example, because the file is missing). |
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Events:
ioError | You cannot write to the file (for example, because the file is missing). This event is dispatched only for files that have been opened for asynchronous operations (by using the openAsync() method). |
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