Package org.bitcoinj.base.internal

Class Buffers

java.lang.Object

org.bitcoinj.base.internal.Buffers

public class Buffers
extends Object

Utility methods for common operations on Bitcoin P2P message buffers.

Constructor Summary

Constructors

Constructor	Description
Buffers()

Method Summary

Modifier and Type	Method	Description
static byte[]	readBytes(ByteBuffer buf, int length)	Read given number of bytes from the buffer.
static byte[]	readLengthPrefixedBytes(ByteBuffer buf)	First read a VarInt from the buffer and use it to determine the number of bytes to be read.
static String	readLengthPrefixedString(ByteBuffer buf)	First read a VarInt from the buffer and use it to determine the number of bytes to read.
static ByteBuffer	skipBytes(ByteBuffer buf, int numBytes)	Advance buffer position by a given number of bytes.
static ByteBuffer	writeLengthPrefixedBytes(ByteBuffer buf, byte[] bytes)	First write the length of the byte array as a VarInt.
static ByteBuffer	writeLengthPrefixedString(ByteBuffer buf, String str)	Encode a given string using UTF-8.

Methods inherited from class java.lang.Object

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

Constructor Details

Buffers

public Buffers()

Method Details

readBytes

public static byte[] readBytes(ByteBuffer buf,
 int length)
                        throws BufferUnderflowException

Read given number of bytes from the buffer.

Parameters:

buf - buffer to read from

length - number of bytes to read

Returns:

bytes read

Throws:

BufferUnderflowException - if the read value extends beyond the remaining bytes of the buffer

readLengthPrefixedBytes

public static byte[] readLengthPrefixedBytes(ByteBuffer buf)
                                      throws BufferUnderflowException

First read a VarInt from the buffer and use it to determine the number of bytes to be read. Then read that many bytes into the byte array to be returned. This construct is frequently used by Bitcoin protocols.

Parameters:

buf - buffer to read from

Returns:

read bytes

Throws:

BufferUnderflowException - if the read value extends beyond the remaining bytes of the buffer

writeLengthPrefixedBytes

public static ByteBuffer writeLengthPrefixedBytes(ByteBuffer buf,
 byte[] bytes)
                                           throws BufferOverflowException

First write the length of the byte array as a VarInt. Then write the array contents.

Parameters:

buf - buffer to write to

bytes - bytes to write

Returns:

the buffer

Throws:

BufferOverflowException - if the value doesn't fit the remaining buffer

readLengthPrefixedString

public static String readLengthPrefixedString(ByteBuffer buf)
                                       throws BufferUnderflowException

First read a VarInt from the buffer and use it to determine the number of bytes to read. Then read that many bytes and interpret it as an UTF-8 encoded string to be returned. This construct is frequently used by Bitcoin protocols.

Parameters:

buf - buffer to read from

Returns:

read string

Throws:

BufferUnderflowException - if the read value extends beyond the remaining bytes of the buffer

writeLengthPrefixedString

public static ByteBuffer writeLengthPrefixedString(ByteBuffer buf,
 String str)
                                            throws BufferOverflowException

Encode a given string using UTF-8. Then write the length of the encoded bytes as a VarInt. Then write the bytes themselves.

Parameters:

buf - buffer to write to

str - string to write

Returns:

the buffer

Throws:

BufferOverflowException - if the value doesn't fit the remaining buffer

skipBytes

public static ByteBuffer skipBytes(ByteBuffer buf,
 int numBytes)
                            throws BufferUnderflowException

Advance buffer position by a given number of bytes.

Parameters:

buf - buffer to skip bytes on

numBytes - number of bytes to skip

Returns:

the buffer

Throws:

BufferUnderflowException - if the read value extends beyond the remaining bytes of the buffer