java - 将 12 个字符转换为长整型

Question

交易的授权金额。格式为“n 12”，长度为 6 个字节，例如值 1234567 存储为十六进制 00 00 01 23 45 67。

TLV > 9F02 06 000001234567

问:如何将000001234567转换为1234567？

我尝试了如下但不起作用:

public static long byteArrayToLong(@NonNull byte[] from, int offset, @NonNull EEndian endian) {
    try {
        byte[] fromFixed = new byte[8];
        if(from.length < 8) {
            System.arraycopy(from, 0, fromFixed, fromFixed.length-from.length, from.length);
        }
        else  {
            System.arraycopy(from, 0, fromFixed, 0, fromFixed.length);
        }
        if (endian == EEndian.BIG_ENDIAN) {
            return ((fromFixed[offset] << 24) & 0xff00000000000000L) | ((fromFixed[offset + 1] << 16) & 0xff000000000000L)
                    | ((fromFixed[offset + 2] << 8) & 0xff0000000000L) | ((fromFixed[offset + 3]) & 0xff00000000L)
                    | ((fromFixed[offset + 4] << 24) & 0xff000000) | ((fromFixed[offset + 5] << 16) & 0xff0000)
                    | ((fromFixed[offset + 6] << 8) & 0xff00) | (fromFixed[offset + 7] & 0xff);
        } else {
            return ((fromFixed[offset + 7] << 24) & 0xff00000000000000L) | ((fromFixed[offset + 6] << 16) & 0xff000000000000L)
                    | ((fromFixed[offset + 5] << 8) & 0xff0000000000L) | ((fromFixed[offset + 4]) & 0xff00000000L)
                    | ((fromFixed[offset + 3] << 24) & 0xff000000) | ((fromFixed[offset + 2] << 16) & 0xff0000)
                    | ((fromFixed[offset + 1] << 8) & 0xff00) | (fromFixed[offset] & 0xff);
        }
    } catch (Exception ex) {
        ex.printStackTrace();
    }
    return -1;
}

//调用上面的代码

byte[] amountAuthorisedNumeric = transLogResponse.getAmountAuthorisedNumeric(i); // new byte[] {(byte)00x00, (byte)0x00, (byte)0x01, (byte)0x23, (byte)0x45, (byte)0x67}
Log.i(TAG, "AMOUNT1 is " + byteArrayToHexString(amountAuthorisedNumeric));       // 000001234567

amount = byteArrayToLong(amountAuthorisedNumeric, 0, BIG_ENDIAN); // error in here
Log.i(TAG, "AMOUNT2 is " + amount);                               // 19088743 (result expected is 1234567, not 19088743)

Answer 1

我建议使用 BigInteger 。

import java.math.BigInteger;

/**
 *
 * @author Sedrick
 */
public class Main
{

    public static void main(String[] args)
    {
        String value = "000001234567";
        BigInteger bigInteger = new BigInteger(value);
        System.out.println(bigInteger.longValue());
    }

}

输出:

--- exec-maven-plugin:1.5.0:exec (default-cli) @ JavaTestingGround ---
1234567
------------------------------------------------------------------------
BUILD SUCCESS

另一条路线是使用 Long 来解析值。

/**
 *
 * @author Sedrick
 */
public class Main
{

    public static void main(String[] args)
    {
        String value = "000001234567";

        System.out.println(Long.parseLong(value));
    }

}

输出:

1234567
------------------------------------------------------------------------
BUILD SUCCESS