org.apache.cassandra.utils
Class ByteBufferUtil

java.lang.Object
  org.apache.cassandra.utils.ByteBufferUtil

public class ByteBufferUtil
extends java.lang.Object

Utility methods to make ByteBuffers less painful The following should illustrate the different ways byte buffers can be used public void testArrayOffet() { byte[] b = "test_slice_array".getBytes(); ByteBuffer bb = ByteBuffer.allocate(1024); assert bb.position() == 0; assert bb.limit() == 1024; assert bb.capacity() == 1024; bb.put(b); assert bb.position() == b.length; assert bb.remaining() == bb.limit() - bb.position(); ByteBuffer bb2 = bb.slice(); assert bb2.position() == 0; //slice should begin at other buffers current position assert bb2.arrayOffset() == bb.position(); //to match the position in the underlying array one needs to //track arrayOffset assert bb2.limit()+bb2.arrayOffset() == bb.limit(); assert bb2.remaining() == bb.remaining(); } }

Field Summary

static java.nio.ByteBuffer

EMPTY_BYTE_BUFFER

Constructor Summary

ByteBufferUtil()

Method Summary

static void	arrayCopy(java.nio.ByteBuffer buffer, int position, byte[] bytes, int offset, int length)
static void	arrayCopy(java.nio.ByteBuffer src, int srcPos, java.nio.ByteBuffer dst, int dstPos, int length) Transfer bytes from one ByteBuffer to another.
static java.nio.ByteBuffer	bytes(double d)
static java.nio.ByteBuffer	bytes(float f)
static java.nio.ByteBuffer	bytes(int i)
static java.nio.ByteBuffer	bytes(long n)
static java.nio.ByteBuffer	bytes(java.lang.String s) Encode a String in a ByteBuffer using UTF_8.
static java.nio.ByteBuffer	bytes(java.lang.String s, java.nio.charset.Charset charset) Encode a String in a ByteBuffer using the provided charset.
static java.lang.String	bytesToHex(java.nio.ByteBuffer bytes)
static java.nio.ByteBuffer	clone(java.nio.ByteBuffer buffer)
static int	compare(byte[] o1, java.nio.ByteBuffer o2)
static int	compare(java.nio.ByteBuffer o1, byte[] o2)
static int	compareSubArrays(java.nio.ByteBuffer bytes1, int offset1, java.nio.ByteBuffer bytes2, int offset2, int length) Compare two ByteBuffer at specified offsets for length.
static int	compareUnsigned(java.nio.ByteBuffer o1, java.nio.ByteBuffer o2)
static byte[]	getArray(java.nio.ByteBuffer buffer) You should almost never use this.
static java.nio.ByteBuffer	hexToBytes(java.lang.String str)
static java.io.InputStream	inputStream(java.nio.ByteBuffer bytes)
static int	lastIndexOf(java.nio.ByteBuffer buffer, byte valueToFind, int startIndex) ByteBuffer adaptation of org.apache.commons.lang.ArrayUtils.lastIndexOf method
static java.nio.ByteBuffer	readWithLength(java.io.DataInput in)
static java.nio.ByteBuffer	readWithShortLength(java.io.DataInput in)
static java.nio.ByteBuffer	skipShortLength(java.io.DataInput in)
static java.lang.String	string(java.nio.ByteBuffer buffer) Decode a String representation.
static java.lang.String	string(java.nio.ByteBuffer buffer, java.nio.charset.Charset charset) Decode a String representation.
static java.lang.String	string(java.nio.ByteBuffer buffer, int position, int length) Decode a String representation.
static java.lang.String	string(java.nio.ByteBuffer buffer, int position, int length, java.nio.charset.Charset charset) Decode a String representation.
static double	toDouble(java.nio.ByteBuffer bytes)
static float	toFloat(java.nio.ByteBuffer bytes)
static int	toInt(java.nio.ByteBuffer bytes) Convert a byte buffer to an integer.
static long	toLong(java.nio.ByteBuffer bytes)
static void	write(java.nio.ByteBuffer buffer, java.io.DataOutput out)
static void	writeWithLength(java.nio.ByteBuffer bytes, java.io.DataOutput out)
static void	writeWithShortLength(java.nio.ByteBuffer buffer, java.io.DataOutput out)

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY_BYTE_BUFFER

public static final java.nio.ByteBuffer EMPTY_BYTE_BUFFER

Constructor Detail

ByteBufferUtil

public ByteBufferUtil()

Method Detail

compareUnsigned

public static int compareUnsigned(java.nio.ByteBuffer o1,
                                  java.nio.ByteBuffer o2)

compare

public static int compare(byte[] o1,
                          java.nio.ByteBuffer o2)

compare

public static int compare(java.nio.ByteBuffer o1,
                          byte[] o2)

string

public static java.lang.String string(java.nio.ByteBuffer buffer)
                               throws java.nio.charset.CharacterCodingException

Decode a String representation. This method assumes that the encoding charset is UTF_8.

Parameters:

buffer - a byte buffer holding the string representation

Returns:

the decoded string

Throws:

java.nio.charset.CharacterCodingException

string

public static java.lang.String string(java.nio.ByteBuffer buffer,
                                      int position,
                                      int length)
                               throws java.nio.charset.CharacterCodingException

Decode a String representation. This method assumes that the encoding charset is UTF_8.

Parameters:

buffer - a byte buffer holding the string representation

position - the starting position in buffer to start decoding from

length - the number of bytes from buffer to use

Returns:

the decoded string

Throws:

java.nio.charset.CharacterCodingException

string

public static java.lang.String string(java.nio.ByteBuffer buffer,
                                      int position,
                                      int length,
                                      java.nio.charset.Charset charset)
                               throws java.nio.charset.CharacterCodingException

Decode a String representation.

Parameters:

buffer - a byte buffer holding the string representation

position - the starting position in buffer to start decoding from

length - the number of bytes from buffer to use

charset - the String encoding charset

Returns:

the decoded string

Throws:

java.nio.charset.CharacterCodingException

string

public static java.lang.String string(java.nio.ByteBuffer buffer,
                                      java.nio.charset.Charset charset)
                               throws java.nio.charset.CharacterCodingException

Decode a String representation.

Parameters:

buffer - a byte buffer holding the string representation

charset - the String encoding charset

Returns:

the decoded string

Throws:

java.nio.charset.CharacterCodingException

getArray

public static byte[] getArray(java.nio.ByteBuffer buffer)

You should almost never use this. Instead, use the write* methods to avoid copies.

lastIndexOf

public static int lastIndexOf(java.nio.ByteBuffer buffer,
                              byte valueToFind,
                              int startIndex)

ByteBuffer adaptation of org.apache.commons.lang.ArrayUtils.lastIndexOf method

Parameters:

buffer - the array to traverse for looking for the object, may be null

valueToFind - the value to find

startIndex - the start index (i.e. BB position) to travers backwards from

Returns:

the last index (i.e. BB position) of the value within the array [between buffer.position() and buffer.limit()]; -1 if not found.

bytes

public static java.nio.ByteBuffer bytes(java.lang.String s)

Encode a String in a ByteBuffer using UTF_8.

Parameters:

s - the string to encode

Returns:

the encoded string

bytes

public static java.nio.ByteBuffer bytes(java.lang.String s,
                                        java.nio.charset.Charset charset)

Encode a String in a ByteBuffer using the provided charset.

Parameters:

s - the string to encode

charset - the String encoding charset to use

Returns:

the encoded string

clone

public static java.nio.ByteBuffer clone(java.nio.ByteBuffer buffer)

Returns:

a new copy of the data in @param buffer USUALLY YOU SHOULD USE ByteBuffer.duplicate() INSTEAD, which creates a new Buffer (so you can mutate its position without affecting the original) without copying the underlying array.

arrayCopy

public static void arrayCopy(java.nio.ByteBuffer buffer,
                             int position,
                             byte[] bytes,
                             int offset,
                             int length)

arrayCopy

public static void arrayCopy(java.nio.ByteBuffer src,
                             int srcPos,
                             java.nio.ByteBuffer dst,
                             int dstPos,
                             int length)

Transfer bytes from one ByteBuffer to another. This function acts as System.arrayCopy() but for ByteBuffers.

Parameters:

src - the source ByteBuffer

srcPos - starting position in the source ByteBuffer

dst - the destination ByteBuffer

dstPos - starting position in the destination ByteBuffer

length - the number of bytes to copy

writeWithLength

public static void writeWithLength(java.nio.ByteBuffer bytes,
                                   java.io.DataOutput out)
                            throws java.io.IOException

Throws:

java.io.IOException

write

public static void write(java.nio.ByteBuffer buffer,
                         java.io.DataOutput out)
                  throws java.io.IOException

Throws:

java.io.IOException

writeWithShortLength

public static void writeWithShortLength(java.nio.ByteBuffer buffer,
                                        java.io.DataOutput out)

readWithLength

public static java.nio.ByteBuffer readWithLength(java.io.DataInput in)
                                          throws java.io.IOException

Throws:

java.io.IOException

readWithShortLength

public static java.nio.ByteBuffer readWithShortLength(java.io.DataInput in)
                                               throws java.io.IOException

Parameters:

in - data input

Returns:

An unsigned short in an integer.

Throws:

java.io.IOException - if an I/O error occurs.

skipShortLength

public static java.nio.ByteBuffer skipShortLength(java.io.DataInput in)
                                           throws java.io.IOException

Parameters:

in - data input

Returns:

null

Throws:

java.io.IOException - if an I/O error occurs.

toInt

public static int toInt(java.nio.ByteBuffer bytes)

Convert a byte buffer to an integer. Does not change the byte buffer position.

Parameters:

bytes - byte buffer to convert to integer

Returns:

int representation of the byte buffer

toLong

public static long toLong(java.nio.ByteBuffer bytes)

toFloat

public static float toFloat(java.nio.ByteBuffer bytes)

toDouble

public static double toDouble(java.nio.ByteBuffer bytes)

bytes

public static java.nio.ByteBuffer bytes(int i)

bytes

public static java.nio.ByteBuffer bytes(long n)

bytes

public static java.nio.ByteBuffer bytes(float f)

bytes

public static java.nio.ByteBuffer bytes(double d)

inputStream

public static java.io.InputStream inputStream(java.nio.ByteBuffer bytes)

bytesToHex

public static java.lang.String bytesToHex(java.nio.ByteBuffer bytes)

hexToBytes

public static java.nio.ByteBuffer hexToBytes(java.lang.String str)

compareSubArrays

public static int compareSubArrays(java.nio.ByteBuffer bytes1,
                                   int offset1,
                                   java.nio.ByteBuffer bytes2,
                                   int offset2,
                                   int length)

Compare two ByteBuffer at specified offsets for length. Compares the non equal bytes as unsigned.

Parameters:

bytes1 - First byte buffer to compare.

offset1 - Position to start the comparison at in the first array.

bytes2 - Second byte buffer to compare.

offset2 - Position to start the comparison at in the second array.

length - How many bytes to compare?

Returns:

-1 if byte1 is less than byte2, 1 if byte2 is less than byte1 or 0 if equal.