[@小川游鱼][¥20]Java 中怎样将 bytes 转换为 long 类型？

com.google.common.primitives.fromByteArray(xxx)

这样是否题目要求的呢？

public class ByteUtil {

private static final long HEX_LONG = 0x0000000000000000L;
private static final byte HEX_BYTE = (byte) 0xff;

public static Long byteToLong(Byte[] bytes) {
    if (bytes == null || bytes.length != 8) {
        throw new RuntimeException("param error.");
    }
    long result = HEX_LONG;
    for (int i = 0; i < bytes.length; i++) {
        long tmp = Byte.toUnsignedLong(bytes[i]);
        tmp <<= (56 - i * 8);
        result = result | tmp;
        // System.out.println(getLongHexStr(result));
    }

    return result;
}

public static String getLongHexStr(long x) {
    StringBuilder sb = new StringBuilder();
    for (int i = 63; i >= 0; i--) {
        sb.append((x & 0x0000000000000001) == 1l ? "1" : "0");
        x >>= 1;
    }
    return sb.reverse().toString();
}

public static Byte[] getBytesFromLong(Long x) {
    Byte[] bytes = new Byte[8];
    for (int i = 0; i < bytes.length; i++) {
        bytes[bytes.length - 1 - i] = (byte) (x & 0x00000000000000ffL);
        x >>= 8;
    }
    return bytes;
}

public static void main(String[] args) {

    System.out.println(byteToLong(getBytesFromLong(1236786534l)));
    System.out.println(byteToLong(getBytesFromLong(-1236786534l)));
    System.out.println(byteToLong(getBytesFromLong(-0l)));
    System.out.println(byteToLong(getBytesFromLong(0l)));

    // System.out.println("Long.maxvalue=" + Long.MAX_VALUE + ",byteToLong="
    // + byteToLong(
    // new Byte[] { HEX_BYTE, HEX_BYTE, HEX_BYTE, HEX_BYTE, HEX_BYTE,
    // HEX_BYTE, HEX_BYTE, HEX_BYTE, }));
}

}

    public static long bytes2long(byte[] param) {
        long result = 0;
        if (param== null || param.length == 0) {
            return result;
        }

        ByteBuffer buffer = ByteBuffer.wrap(param);
        return buffer.getLong();
    }