com.credibledoc.iso8583packer.length.LengthPacker Maven / Gradle / Ivy
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package com.credibledoc.iso8583packer.length;
import com.credibledoc.iso8583packer.hex.HexLengthPacker;
import com.credibledoc.iso8583packer.message.MsgValue;
/**
* Actual documentation and examples
* length-packer.md.
*
* The interface contains methods for packing and unpacking the {@link MsgValue#getLengthBytes()} subfield.
* The subfield contains length of the {@link MsgValue#getBodyBytes()} subfield.
*
* Example of usage: {@link com.credibledoc.iso8583packer.FieldBuilder#defineHeaderLengthPacker(LengthPacker)}.
*
* FieldBuilder.builder(MsgFieldType.LEN_VAL)
* .defineHeaderLengthPacker(BcdLengthPacker.getInstance(2))
* ...
*
*
* @author Kyrylo Semenko
*/
public interface LengthPacker {
/**
* Pack a number how many bytes contains the {@link com.credibledoc.iso8583packer.message.MsgValue#getBodyBytes()} subfield.
*
* @param bodyBytesLength the number to be encoded and packed.
* @return The encoded and packed bytes of the {@link MsgValue#getBodyBytes()} subfield.
*/
byte[] pack(int bodyBytesLength);
/**
* Unpack a number how many bytes contains the {@link MsgValue#getBodyBytes()} subfield.
*
* @param messageBytes packed bytes of incoming message.
* @param offset how many bytes to skip.
* @return Number of bytes to be unpacked from the messageBytes to the {@link MsgValue#setBodyBytes(byte[])} subfield.
*/
int unpack(byte[] messageBytes, int offset);
/**
* Some {@link LengthPacker}s has constant bytes length of the header part where packed length is a subfield
* of a {@link MsgValue#getLengthBytes()} data.
*
* Others calculate the value depend on first byte value, for example see {@link HexLengthPacker}.
*
* Obtained value is used for offset shifting during data unpacking.
*
* @param data message part started with field length bytes.
* @param offset number of bytes in the data to skip.
* @return Unpacked field data length.
*/
int calculateLenLength(byte[] data, int offset);
}