entagged.audioformats.asf.util
Class Utils

java.lang.Object
  entagged.audioformats.asf.util.Utils

public class Utils
extends Object

Some static Methods which are used in several Classes.

Author:

Christian Laireiter

Field Summary

static String

LINE_SEPARATOR Stores the default line seperator of the current underlying system.

Constructor Summary

Utils()

Method Summary

static void	checkStringLengthNullSafe(String value) This method converts the given string into a byte[] in UTF-16LE encoding and checks whether the length doesn't exceed 65535 bytes.
static void	fillChars(char[] chars, RandomAccessFile raf) Reads chars out of raf until chars is filled.
static byte[]	getBytes(long value, int byteCount) This method will create a byte[] at the size of byteCount and insert the bytes of value (starting from lowset byte) into it.
static GregorianCalendar	getDateOf(BigInteger fileTime) Since date values in asf files are given in 100 ns steps since first january of 1601 a little conversion must be done.
static int	read7Bit(RandomAccessFile raf) This method reads one byte from raf and creates an unsigned value of it.
static BigInteger	readBig64(RandomAccessFile raf) This method reads 8 bytes, interprets them as an unsigned number and creates a BigInteger
static String	readCharacterSizedString(RandomAccessFile raf) This method reads a UTF-16 String, which legth is given on the number of characters it consits of.
static GUID	readGUID(RandomAccessFile raf) This Method reads a GUID (which is a 16 byte long sequence) from the given raf and creates a wrapper.
static int	readUINT16(RandomAccessFile raf)
static long	readUINT32(RandomAccessFile raf)
static long	readUINT64(RandomAccessFile raf) Reads long as little endian.
static String	readUTF16LEStr(RandomAccessFile raf) This method reads a UTF-16 encoded String, beginning with a 16-bit value representing the number of bytes needed.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LINE_SEPARATOR

public static final String LINE_SEPARATOR

Stores the default line seperator of the current underlying system.

Constructor Detail

Utils

public Utils()

Method Detail

fillChars

public static void fillChars(char[] chars,
                             RandomAccessFile raf)
                      throws IOException

Reads chars out of raf until chars is filled.

Parameters:

chars - to be filled

raf - to be read

Throws:

IOException - read error, or file at end before chars is filled.

getBytes

public static byte[] getBytes(long value,
                              int byteCount)

This method will create a byte[] at the size of byteCount and insert the bytes of value (starting from lowset byte) into it.
You can easily create a Word (16-bit), DWORD (32-bit), QWORD (64 bit) out of the value, ignoring the original type of value, since java automatically performs transformations.
Warning: This method works with unsigned numbers only.

Parameters:

value - The value to be written into the result.

byteCount - The number of bytes the array has got.

Returns:

A byte[] with the size of byteCount containing the lower byte values of value.

getDateOf

public static GregorianCalendar getDateOf(BigInteger fileTime)

Since date values in asf files are given in 100 ns steps since first january of 1601 a little conversion must be done.
This method converts a date given in described manner to a calendar.

Parameters:

fileTime - Time in 100ns since 1 jan 1601

Returns:

Calendar holding the date representation.

read7Bit

public static int read7Bit(RandomAccessFile raf)
                    throws IOException

This method reads one byte from raf and creates an unsigned value of it.

Parameters:

raf - The file to read from.

Returns:

next 7 bits as number.

Throws:

IOException - read errors.

readBig64

public static BigInteger readBig64(RandomAccessFile raf)
                            throws IOException

This method reads 8 bytes, interprets them as an unsigned number and creates a BigInteger

Parameters:

raf - Input source

Returns:

8 bytes unsigned number

Throws:

IOException - read errors.

readCharacterSizedString

public static String readCharacterSizedString(RandomAccessFile raf)
                                       throws IOException

This method reads a UTF-16 String, which legth is given on the number of characters it consits of.
The filepointer of raf must be at the number of characters. This number contains the terminating zero character (UINT16).

Parameters:

raf - Input source

Returns:

String

Throws:

IOException - read errors

readGUID

public static GUID readGUID(RandomAccessFile raf)
                     throws IOException

This Method reads a GUID (which is a 16 byte long sequence) from the given raf and creates a wrapper.
Warning :
There is no way of telling if a byte sequence is a guid or not. The next 16 bytes will be interpreted as a guid, whether it is or not.

Parameters:

raf - Input source.

Returns:

A class wrapping the guid.

Throws:

IOException - happens when the file ends before guid could be extracted.

readUINT16

public static int readUINT16(RandomAccessFile raf)
                      throws IOException

Parameters:

raf -

Returns:

number

Throws:

IOException

See Also:

readUINT64(RandomAccessFile)

readUINT32

public static long readUINT32(RandomAccessFile raf)
                       throws IOException

Parameters:

raf -

Returns:

number

Throws:

IOException

See Also:

readUINT64(RandomAccessFile)

readUINT64

public static long readUINT64(RandomAccessFile raf)
                       throws IOException

Reads long as little endian.

Parameters:

raf - Data source

Returns:

long value

Throws:

IOException - read error, or eof is reached before long is completed

readUTF16LEStr

public static String readUTF16LEStr(RandomAccessFile raf)
                             throws IOException

This method reads a UTF-16 encoded String, beginning with a 16-bit value representing the number of bytes needed. The String is terminated with as 16-bit ZERO.

Parameters:

raf - Input source

Returns:

read String.

Throws:

IOException - read errors.

checkStringLengthNullSafe

public static void checkStringLengthNullSafe(String value)
                                      throws IllegalArgumentException

This method converts the given string into a byte[] in UTF-16LE encoding and checks whether the length doesn't exceed 65535 bytes.

Parameters:

value - The string to check.

Throws:

IllegalArgumentException - If byte representation takes more than 65535 bytes.