| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
The ByteArray class provides methods and properties to optimize reading, writing,
and working with binary data.
Note: The ByteArray class is for advanced developers who need to access
data on the byte level.
In-memory data is a packed array (the most compact representation for the data type)
of bytes, but an instance of the ByteArray
class can be manipulated with the standard [] (array access) operators.
It also can be read and written to as an in-memory file, using
methods similar to those in the URLStream and Socket classes.
In addition, zlib compression and decompression are supported, as
well as Action Message Format (AMF) object serialization.
Possible uses of the ByteArray class include the following:
- Creating a custom protocol to connect to a server.
- Writing your own URLEncoder/URLDecoder.
- Writing your own AMF/Remoting packet.
- Optimizing the size of your data by using data types.
- Working with binary data loaded from a file in
Adobe® AIR®.
View the examples
bytesAvailable:uint [read-only]
| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
The number of bytes of data available for reading
from the current position in the byte array to the
end of the array.
Use the bytesAvailable property in conjunction
with the read methods each time you access a ByteArray object
to ensure that you are reading valid data.
Implementation public function get bytesAvailable():uintdefaultObjectEncoding:uint| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Denotes the default object encoding for the ByteArray class to use for a new ByteArray instance.
When you create a new ByteArray instance, the encoding on that instance starts
with the value of defaultObjectEncoding.
The defaultObjectEncoding property is initialized to ObjectEncoding.AMF3.
When an object is written to or read from binary data, the objectEncoding value
is used to determine whether the ActionScript 3.0, ActionScript2.0, or ActionScript 1.0 format should be used. The value is a
constant from the ObjectEncoding class.
Implementation public static function get defaultObjectEncoding():uint public function set defaultObjectEncoding(value:uint):voidSee also
endian:String| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Changes or reads the byte order for the data; either Endian.BIG_ENDIAN or
Endian.LITTLE_ENDIAN.
Implementation public function get endian():String public function set endian(value:String):voidSee also
length:uint| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
The length of the ByteArray object, in bytes.
If the length is set to a value that is larger than the current length,
the the right side of the byte array is filled with zeros.
If the length is set to a value that is smaller than the
current length, the byte array is truncated.
Implementation public function get length():uint public function set length(value:uint):voidobjectEncoding:uint| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Used to determine whether the ActionScript 3.0, ActionScript 2.0, or ActionScript 1.0 format should be
used when writing to, or reading from, a ByteArray instance. The value is a
constant from the ObjectEncoding class.
Implementation public function get objectEncoding():uint public function set objectEncoding(value:uint):voidSee also
position:uint| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Moves, or returns the current position, in bytes, of the file
pointer into the ByteArray object. This is the
point at which the next call to a read
method starts reading or a write
method starts writing.
Implementation public function get position():uint public function set position(value:uint):voidpublic function ByteArray()| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Creates a ByteArray instance representing a packed array of bytes, so that you can use the methods and properties in this class to optimize your data storage and stream.
public function clear():void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
Clears the contents of the byte array and resets the length
and position properties to 0. Calling this method explicitly
frees up the memory used by the ByteArray instance.
public function compress(algorithm:String):void| Runtime Versions: | AIR 1.0 |
Compresses the byte array. The entire byte array is compressed. For content
running in Adobe AIR, you can specify a compression algorithm by passing a
value (defined in the CompressionAlgorithm class) as the algorithm
parameter. Flash Player supports only the default
algorithm, zlib.
After the call, the length property of the ByteArray is set to the new length.
The position property is set to the end of the byte array.
The zlib compressed data format is described at
http://www.ietf.org/rfc/rfc1950.txt.
The deflate compression algorithm is described at
http://www.ietf.org/rfc/rfc1951.txt.
The deflate compression algorithm is used in several compression
formats, such as zlib, gzip, some zip implementations, and others. When data is
compressed using one of those compression formats, in addition to storing
the compressed version of the original data, the compression format data
(for example, the .zip file) includes metadata information. Some examples of
the types of metadata included in various file formats are file name,
file modification date/time, original file size, optional comments, checksum
data, and more.
For example, when a ByteArray is compressed using the zlib algorithm,
the resulting ByteArray is structured in a specific format. Certain bytes contain
metadata about the compressed data, while other bytes contain the actual compressed
version of the original ByteArray data. As defined by the zlib compressed data
format specification, those bytes (that is, the portion containing
the compressed version of the original data) are compressed using the deflate
algorithm. Consequently those bytes are identical to the result of calling
compress(CompressionAlgorithm.DEFLATE)
on the original ByteArray. However, the result from
compress(CompressionAlgorithm.ZLIB) includes
the extra metadata, while the compress(CompressionAlgorithm.DEFLATE)
result includes only the compressed version of the original ByteArray data and nothing else.
In order to use the deflate format to compress a ByteArray instance's
data in a specific format such as gzip or zip, you cannot simply call
compress(CompressionAlgorithm.DEFLATE).
You must create a ByteArray structured
according to the compression format's specification, including the appropriate
metadata as well as the compressed data obtained using the deflate format.
Likewise, in order to decode data compressed in a format such
as gzip or zip, you can't simply call uncompress(CompressionAlgorithm.DEFLATE)
on that data. First, you must separate the metadata from the compressed data, and you can
then use the deflate format to decompress the compressed data.
Parameters
| algorithm:String (default = NaN)compress(CompressionAlgorithm.DEFLATE)
has the same effect as calling the deflate() method.
|
See also
public function deflate():void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
Compresses the byte array using the deflate compression algorithm.
The entire byte array is compressed.
After the call, the length property of the ByteArray is set to the new length.
The position property is set to the end of the byte array.
The deflate compression algorithm is described at
http://www.ietf.org/rfc/rfc1951.txt.
In order to use the deflate format to compress a ByteArray instance's
data in a specific format such as gzip or zip, you cannot simply call
deflate(). You must create a ByteArray structured
according to the compression format's specification, including the appropriate
metadata as well as the compressed data obtained using the deflate format.
Likewise, in order to decode data compressed in a format such
as gzip or zip, you can't simply call inflate()
on that data. First, you must separate the metadata from the compressed data, and you can
then use the deflate format to decompress the compressed data.
See also
public function inflate():void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 10, AIR 1.0 |
Decompresses the byte array using the deflate compression algorithm.
The byte array must have been compressed using the same algorithm.
After the call, the length property of the ByteArray is set to the new length.
The position property is set to 0.
The deflate compression algorithm is described at
http://www.ietf.org/rfc/rfc1951.txt.
In order to decode data compressed in a format that uses the deflate compression algorithm,
such as data in gzip or zip format, it will not work to simply call inflate() on
a ByteArray containing the compression formation data. First, you must separate the metadata that is
included as part of the compressed data format from the actual compressed data. For more
information, see the compress() method description.
Throws | IOError — The data is not valid compressed data; it was not compressed with the
same compression algorithm used to compress.
|
See also
public function readBoolean():Boolean| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Reads a Boolean value from the byte stream. A single byte is read,
and true is returned if the byte is nonzero,
false otherwise.
Returns | Boolean — Returns true if the byte is nonzero, false otherwise.
|
Throws | EOFError — There is not sufficient data available
to read.
|
public function readByte():int| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Reads a signed byte from the byte stream.
The returned value is in the range -128 to 127.
Returns | int — An integer between -128 and 127.
|
Throws | EOFError — There is not sufficient data available
to read.
|
public function readBytes(bytes:ByteArray, offset:uint = 0, length:uint = 0):void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Reads the number of data bytes, specified by the length parameter, from the byte stream.
The bytes are read into the ByteArray object specified by the bytes parameter,
and the bytes are written into the destination ByteArray starting at the position specified by offset.
Parameters
| bytes:ByteArray — The ByteArray object to read data into.
|
| |
| offset:uint (default = 0)bytes at which the read data should be written.
|
| |
| length:uint (default = 0) |
Throws | EOFError — There is not sufficient data available
to read.
|
public function readDouble():Number| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Reads an IEEE 754 double-precision (64-bit) floating-point number from the byte stream.
Returns | Number — A double-precision (64-bit) floating-point number.
|
Throws | EOFError — There is not sufficient data available
to read.
|
public function readFloat():Number| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Reads an IEEE 754 single-precision (32-bit) floating-point number from the byte stream.
Returns | Number — A single-precision (32-bit) floating-point number.
|
Throws | EOFError — There is not sufficient data available
to read.
|
public function readInt():int| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Reads a signed 32-bit integer from the byte stream.
The returned value is in the range -2147483648 to 2147483647.
Returns | int — A 32-bit signed integer between -2147483648 and 2147483647.
|
Throws | EOFError — There is not sufficient data available
to read.
|
public function readMultiByte(length:uint, charSet:String):String| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Reads a multibyte string of specified length from the byte stream using the
specified character set.
Parameters
| length:uint — The number of bytes from the byte stream to read.
|
| |
| charSet:String — 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.
For a complete list, see Supported Character Sets.
Note: If the value for the charSet parameter
is not recognized by the current system, the application uses the system's default
code page as the character set. For example, a value for the charSet parameter,
as in myTest.readMultiByte(22, "iso-8859-01") that uses 01 instead of
1 might work on your development machine, but not on another machine.
On the other machine, the application will use the system's default code page.
|
Returns | String — UTF-8 encoded string.
|
Throws | EOFError — There is not sufficient data available
to read.
|
public function readObject():*| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Reads an object from the byte array, encoded in AMF
serialized format.
Returns | * — The deserialized object.
|
Throws | EOFError — There is not sufficient data available
to read.
|
See also
public function readShort():int| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Reads a signed 16-bit integer from the byte stream.
The returned value is in the range -32768 to 32767.
Returns | int — A 16-bit signed integer between -32768 and 32767.
|
Throws | EOFError — There is not sufficient data available
to read.
|
public function readUnsignedByte():uint| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Reads an unsigned byte from the byte stream.
The returned value is in the range 0 to 255.
Returns | uint — A 32-bit unsigned integer between 0 and 255.
|
Throws | EOFError — There is not sufficient data available
to read.
|
public function readUnsignedInt():uint| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Reads an unsigned 32-bit integer from the byte stream.
The returned value is in the range 0 to 4294967295.
Returns | uint — A 32-bit unsigned integer between 0 and 4294967295.
|
Throws | EOFError — There is not sufficient data available
to read.
|
public function readUnsignedShort():uint| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Reads an unsigned 16-bit integer from the byte stream.
The returned value is in the range 0 to 65535.
Returns | uint — A 16-bit unsigned integer between 0 and 65535.
|
Throws | EOFError — There is not sufficient data available
to read.
|
public function readUTF():String| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Reads a UTF-8 string from the byte stream. The string
is assumed to be prefixed with an unsigned short indicating
the length in bytes.
Returns | String — UTF-8 encoded string.
|
Throws | EOFError — There is not sufficient data available
to read.
|
See also
public function readUTFBytes(length:uint):String| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Reads a sequence of UTF-8 bytes specified by the length
parameter from the byte stream and returns a string.
Parameters
| length:uint — An unsigned short indicating the length of the UTF-8 bytes.
|
Returns | String — A string composed of the UTF-8 bytes of the specified length.
|
Throws | EOFError — There is not sufficient data available
to read.
|
public function toString():String| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Converts the byte array to a string.
If the data in the array begins with a Unicode byte order mark, the application will honor that mark
when converting to a string. If System.useCodePage is set to true, the
application will treat the data in the array as being in the current system code page when converting.
Returns | String — The string representation of the byte array.
|
public function uncompress(algorithm:String):void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Decompresses the byte array. For content running in Adobe AIR, you can specify
a compression algorithm by passing a value (defined in the CompressionAlgorithm class)
as the algorithm parameter. The byte array must have been compressed
using the same algorithm. Flash Player supports only the
default algorithm, zlib.
After the call, the length property of the ByteArray is set to the new length.
The position property is set to 0.
The zlib compressed data format is described at
http://www.ietf.org/rfc/rfc1950.txt.
The deflate compression algorithm is described at
http://www.ietf.org/rfc/rfc1951.txt.
In order to decode data compressed in a format that uses the deflate compression algorithm,
such as data in gzip or zip format, it will not work to call
uncompress(CompressionAlgorithm.DEFLATE) on
a ByteArray containing the compression formation data. First, you must separate the metadata that is
included as part of the compressed data format from the actual compressed data. For more
information, see the compress() method description.
Parameters
| algorithm:String (default = NaN) |
Throws | IOError — The data is not valid compressed data; it was not compressed with the
same compression algorithm used to compress.
|
See also
public function writeBoolean(value:Boolean):void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Writes a Boolean value. A single byte is written according to the value parameter,
either 1 if true or 0 if false.
Parameters
| value:Boolean — A Boolean value determining which byte is written. If the parameter is true,
the method writes a 1; if false, the method writes a 0.
|
public function writeByte(value:int):void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Writes a byte to the byte stream.
The low 8 bits of the
parameter are used. The high 24 bits are ignored.
Parameters
| value:int — A 32-bit integer. The low 8 bits are written to the byte stream.
|
public function writeBytes(bytes:ByteArray, offset:uint = 0, length:uint = 0):void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Writes a sequence of length bytes from the
specified byte array, bytes,
starting offset (zero-based index) bytes
into the byte stream.
If the length parameter is omitted, the default
length of 0 is used; the method writes the entire buffer starting at
offset.
If the offset parameter is also omitted, the entire buffer is
written.
If offset or length
is out of range, they are clamped to the beginning and end
of the bytes array.
Parameters
| bytes:ByteArray — The ByteArray object.
|
| |
| offset:uint (default = 0) |
| |
| length:uint (default = 0) |
public function writeDouble(value:Number):void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Writes an IEEE 754 double-precision (64-bit) floating-point number to the byte stream.
Parameters
| value:Number — A double-precision (64-bit) floating-point number.
|
public function writeFloat(value:Number):void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Writes an IEEE 754 single-precision (32-bit) floating-point number to the byte stream.
Parameters
| value:Number — A single-precision (32-bit) floating-point number.
|
public function writeInt(value:int):void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Writes a 32-bit signed integer to the byte stream.
Parameters
| value:int — An integer to write to the byte stream.
|
public function writeMultiByte(value:String, charSet:String):void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Writes a multibyte string to the byte stream using the specified character set.
Parameters
| value:String — The string value to be written.
|
| |
| charSet:String — The string denoting the character set to use. Possible character set strings
include "shift-jis", "cn-gb", "iso-8859-1", and others.
For a complete list, see Supported Character Sets.
|
public function writeObject(object:*):void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Writes an object into the byte array in AMF
serialized format.
Parameters
| object:* — The object to serialize.
|
See also
public function writeShort(value:int):void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Writes a 16-bit integer to the byte stream. The low 16 bits of the parameter are used.
The high 16 bits are ignored.
Parameters
| value:int — 32-bit integer, whose low 16 bits are written to the byte stream.
|
public function writeUnsignedInt(value:uint):void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Writes a 32-bit unsigned integer to the byte stream.
Parameters
| value:uint — An unsigned integer to write to the byte stream.
|
public function writeUTF(value:String):void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Writes a UTF-8 string to the byte stream. 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:String — The string value to be written.
|
Throws public function writeUTFBytes(value:String):void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 9, AIR 1.0 |
Writes a UTF-8 string to the byte stream. Similar to the writeUTF() method,
but writeUTFBytes() does not prefix the string with a 16-bit length word.
Parameters
| value:String — The string value to be written.
|
The following example uses the class
ByteArrayExample to write a Boolean
and the double-precision floating-point representation of pi to a byte array. This is accomplished
using the following steps:
- Declare a new ByteArray object instance
byteArr. - Write the byte-equivalent value of the Boolean
false and then check the length and
read it back. - Write the double-precision floating-point equivalent of the mathematical value of pi.
- Read back each of the nine bytes written into the byte array.
Note: when trace() is called on a byte, it prints the decimal equivalent
of the bytes stored in the byte array.
Notice how a code segment is added at the end to check for end of file errors to ensure that
the byte stream is not read past its end.
package {
import flash.display.Sprite;
import flash.utils.ByteArray;
import flash.errors.EOFError;
public class ByteArrayExample extends Sprite {
public function ByteArrayExample() {
var byteArr:ByteArray = new ByteArray();
byteArr.writeBoolean(false);
trace(byteArr.length); // 1
trace(byteArr[0]); // 0
byteArr.writeDouble(Math.PI);
trace(byteArr.length); // 9
trace(byteArr[0]); // 0
trace(byteArr[1]); // 64
trace(byteArr[2]); // 9
trace(byteArr[3]); // 33
trace(byteArr[4]); // 251
trace(byteArr[5]); // 84
trace(byteArr[6]); // 68
trace(byteArr[7]); // 45
trace(byteArr[8]); // 24
byteArr.position = 0;
try {
trace(byteArr.readBoolean() == false); // true
}
catch(e:EOFError) {
trace(e); // EOFError: Error #2030: End of file was encountered.
}
try {
trace(byteArr.readDouble()); // 3.141592653589793
}
catch(e:EOFError) {
trace(e); // EOFError: Error #2030: End of file was encountered.
}
try {
trace(byteArr.readDouble());
}
catch(e:EOFError) {
trace(e); // EOFError: Error #2030: End of file was encountered.
}
}
}
}
© 2009 Adobe Systems Incorporated. All rights reserved.
Sat Oct 3 2009, 04:15 AM -07:00 
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