无法在java中将comp 3解压缩为numeric

Question

import java.math.BigInteger;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

/**
 * Converts between integer and an array of bytes in IBM mainframe packed
 * decimal format. The number of bytes required to store an integer is (digits +
 * 1) / 2. For example, a 7 digit number can be stored in 4 bytes. Each pair of
 * digits is packed into the two nibbles of one byte. The last nibble contains
 * the sign, 0F for positive and 0C for negative. For example 7654321 becomes
 * 0x76 0x54 0x32 0x1F.
 * 
 * This class is immutable. Once constructed you can extract the value as an
 * int, an array of bytes but you cannot change the value. Someone should
 * implement equals() and hashcode() to make this thing truly useful.
 */

public class PackedDecimalToComp {

    public static void main(String[] args) {

        try {
            // test.unpackData(" 0x12345s");
            Path path = Paths.get("C:\\Users\\AV00499269\\Desktop\\Comp3 data file\\Comp3Test.txt");
            byte[] data = Files.readAllBytes(path);
            PackedDecimalToComp test = new PackedDecimalToComp();
            test.unpackData(data);
        } catch (Exception ex) {
            System.out.println("Exception is :" + ex.getMessage());
        }    
    }

    private static String unpackData(byte[] packedData) {
        String unpackedData = "";

        final int negativeSign = 13;
        for (int currentCharIndex = 0; currentCharIndex < packedData.length; currentCharIndex++) {
            byte firstDigit = (byte) ((packedData[currentCharIndex] >>> 4) & 0x0F);
            byte secondDigit = (byte) (packedData[currentCharIndex] & 0x0F);
            unpackedData += String.valueOf(firstDigit);
            if (currentCharIndex == (packedData.length - 1)) {
                if (secondDigit == negativeSign) {
                    unpackedData = "-" + unpackedData;
                }
            } else {
                unpackedData += String.valueOf(secondDigit);
            }
        }
        System.out.println("Unpackeddata is :" + unpackedData);

        return unpackedData;
    }    
}

转换后，我得到的解压缩数据为783031394

Answer 1

您可以使用IBM Record Generator for Java这一免费工具。

这允许您生成一个表示COBOL或PL/I DSECT的Java类，然后您可以在自己的代码中使用它来读/写大多数COBOL和PL/I数据类型的值。如果您不使用结构，那么您可以通过代码看到底层JZOS类是如何与DataType交互的。

虽然该工具是免费的，但它受到IBM的支持，所以如果遇到问题，可以向IBM提出问题，他们会解决的。