com.credibledoc.iso8583packer.asciihex.AsciiBodyPacker Maven / Gradle / Ivy

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package com.credibledoc.iso8583packer.asciihex;

import com.credibledoc.iso8583packer.body.BodyPacker;
import com.credibledoc.iso8583packer.exception.PackerRuntimeException;

import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

/**
 * Implements ASCII {@link BodyPacker} of String value. Strings are converted to and from ASCII bytes.
 * The packer uses the {@link #ISO_88591} encoding.
 * 
 * More examples
 * ascii-body-packer.md
 * 
 * @author Kyrylo Semenko
 */
public class AsciiBodyPacker implements BodyPacker {

    private static final Charset ISO_88591 = StandardCharsets.ISO_8859_1;

    /**
     * Single instance.
     */
    private static final AsciiBodyPacker instance = new AsciiBodyPacker();

    /**
     * Only one instance is allowed, see the {@link #getInstance()} method.
     */
    private AsciiBodyPacker() {
        // empty
    }

    /**
     * @return The {@link #instance} singleton.
     */
    public static AsciiBodyPacker getInstance() {
        return instance;
    }

    /**
     * @param object the data to be packed. Expected String value.
     * @param bytes  an empty or partially filled bytes.
     * @param offset the index of the first unfilled byte in the bytes array from start packing at.
     */
    @Override
    public void pack(Object object, byte[] bytes, int offset) {
        if (object == null) {
            return;
        }
        if (!(object instanceof String)) {
            throw new PackerRuntimeException("Expected String but found " + object.getClass().getName());
        }
        String data = (String) object;
        int availableBytesLength = bytes.length - offset;
        if (data.length() > availableBytesLength) {
            throw new PackerRuntimeException("Byte array available length '" + availableBytesLength +
                "' is less than required data length '" + data.length() + "'");
        }
        for (int i = data.length() - 1; i >= 0; i--) {
            bytes[offset + i] = (byte) data.charAt(i);
        }
    }

    @Override
    @SuppressWarnings("unchecked")
    public String unpack(byte[] sourceData, int offset, int bytesCount) {
        int available = sourceData.length - offset;
        if (bytesCount > available) {
            throw new PackerRuntimeException("Required bytes length '" + bytesCount +
                "' is greater than available sourceData length '" + available + "'");
        }
        byte[] ret = new byte[bytesCount];
        System.arraycopy(sourceData, offset, ret, 0, bytesCount);
        return new String(ret, ISO_88591);
    }

    @Override
    public int getPackedLength(Object object) {
        if (object == null) {
            return 0;
        }
        if (!(object instanceof String)) {
            throw new PackerRuntimeException("Expected String but found " + object.getClass().getName());
        }

        String string = (String) object;

        return string.length();
    }
}