Byte数组相关工具类

左手的ㄟ右手 2024-04-07 13:40 83阅读 0赞

byte 转换基本数据类型

1.  kotlin 中可以直接调用 toByte , toInt 之类的函数直接获取。
2.  java 中需要自己获取，获取方式会放到工具类中。

大端和小端

下面是对连个模式的简单解释。

*  大端模式：是指数据的高字节保存在内存的低地址中，而数据的低字节保存在内存的高地址中，这样的存储模式有点儿类似于 把数据当作字符串顺序处理：地址由小向大增加，而数据从高位往低位放；这和我们的阅读习惯一致。
 *  小端模式：是指数据的高字节保存在内存的高地址中，而数据的低字节保存在内存的低地址中。

更详细的可以参考这篇博客，[详解大端模式和小端模式][Link 1]。

#### 1、函数列表 ####

int2BytesBig		:将int转为高字节在前，低字节在后的byte数组（大端）
    int2BytesLittle		:将int转为低字节在前，高字节在后的byte数组（小端）
    bytes2IntLittle		:byte数组到int的转换(小端)
    bytes2IntBig		:byte数组到int的转换(大端)
    
    short2BytesBig		:将short转为高字节在前，低字节在后的byte数组（大端）
    short2BytesLittle	:将short转为低字节在前，高字节在后的byte数组(小端)
    bytes2ShortLittle	:读取小端byte数组为short
    bytes2ShortBig		:读取大端byte数组为short
    
    long2BytesBig		:long类型转byte[] (大端)
    long2BytesLittle	:long类型转byte[] (小端)
    bytes2LongLittle	:byte[]转long类型(小端)
    bytes2LongBig		:byte[]转long类型(大端)
    
    long2BytesBOS		:long类型转byte[] (大端),通过ByteArrayOutputStream实现
    bytes2LongBOS		:byte[]转long类型(大端),通过ByteArrayOutputStream实现
    long2BytesByteBuffer:long类型转byte[] (大端),通过ByteBuffer实现
    bytes2LongByteBuffer:byte[]转long类型(大端), 通过ByteBuffer实现
    
    bytes2Long			:将字节数组转为long,支持大小端
    bytes2LongByteBuffer:将字节数组转为long,支持大小端
    
    int2Byte			:int 转 byte
    byte2Int			:byte 转 int,解决java中byte输出可能为负数的问题
    object2Bytes		:将 object --> byte 数组
    bytes2Object		:数组转对象
    
    bytesEquals			:两个byte[]是否相同
    subBytes			:截取byte[]
    bytesMerger			:拼接byte[] 和 byte[]
    bytesMerger			:拼接byte 和 byte[]
    bytesMerger			:拼接byte[] 和 byte
    bytesMerger			:拼接三个数组
    
    byte2Hex      :byte转Hex 16 进制字符串
    bytes2Hex     :byte[]转Hex
    bytes2Hex2      :字节数组转为16进制字符串
    hex2Byte      :Hex转byte,hex只能含两个字符，如果是一个字符byte高位会是0
    hex2Bytes     :Hex转byte[]，两种情况，Hex长度为奇数最后一个字符会被舍去
    str2HexStr      :字符串转为16进制字符串，推荐
    hexStr2Str      :16进制直接转换成为字符串(无需Unicode解码)，推荐
    string2Unicode    :字符串转换unicode
    unicode2String    :unicode 转字符串

#### 2、工具类 ####

public class BytesUtils {
    
        /**
         * 将int转为高字节在前，低字节在后的byte数组（大端）
         *
         * @param n int
         * @return byte[]
         */
        public static byte[] int2BytesBig(int n) {
            byte[] b = new byte[4];
            b[3] = (byte) (n & 0xff);
            b[2] = (byte) (n >> 8 & 0xff);
            b[1] = (byte) (n >> 16 & 0xff);
            b[0] = (byte) (n >> 24 & 0xff);
            return b;
        }
    
        /**
         * 将int转为低字节在前，高字节在后的byte数组（小端）
         *
         * @param n int
         * @return byte[]
         */
        public static byte[] int2BytesLittle(int n) {
            byte[] b = new byte[4];
            b[0] = (byte) (n & 0xff);
            b[1] = (byte) (n >> 8 & 0xff);
            b[2] = (byte) (n >> 16 & 0xff);
            b[3] = (byte) (n >> 24 & 0xff);
            return b;
        }
    
        /**
         * byte数组到int的转换(小端)
         *
         * @param bytes
         * @return
         */
        public static int bytes2IntLittle(byte[] bytes) {
            int int1 = bytes[0] & 0xff;
            int int2 = (bytes[1] & 0xff) << 8;
            int int3 = (bytes[2] & 0xff) << 16;
            int int4 = (bytes[3] & 0xff) << 24;
    
            return int1 | int2 | int3 | int4;
        }
    
        /**
         * byte数组到int的转换(大端)
         *
         * @param bytes
         * @return
         */
        public static int bytes2IntBig(byte[] bytes) {
            int int1 = bytes[3] & 0xff;
            int int2 = (bytes[2] & 0xff) << 8;
            int int3 = (bytes[1] & 0xff) << 16;
            int int4 = (bytes[0] & 0xff) << 24;
    
            return int1 | int2 | int3 | int4;
        }
    
        /**
         * 将short转为高字节在前，低字节在后的byte数组（大端）
         *
         * @param n short
         * @return byte[]
         */
        public static byte[] short2BytesBig(short n) {
            byte[] b = new byte[2];
            b[1] = (byte) (n & 0xff);
            b[0] = (byte) (n >> 8 & 0xff);
            return b;
        }
    
        /**
         * 将short转为低字节在前，高字节在后的byte数组(小端)
         *
         * @param n short
         * @return byte[]
         */
        public static byte[] short2BytesLittle(short n) {
            byte[] b = new byte[2];
            b[0] = (byte) (n & 0xff);
            b[1] = (byte) (n >> 8 & 0xff);
            return b;
        }
    
        /**
         * 读取小端byte数组为short
         *
         * @param b
         * @return
         */
        public static short bytes2ShortLittle(byte[] b) {
            return (short) (((b[1] << 8) | b[0] & 0xff));
        }
    
        /**
         * 读取大端byte数组为short
         *
         * @param b
         * @return
         */
        public static short bytes2ShortBig(byte[] b) {
            return (short) (((b[0] << 8) | b[1] & 0xff));
        }
    
        /**
         * long类型转byte[] (大端)
         *
         * @param n
         * @return
         */
        public static byte[] long2BytesBig(long n) {
            byte[] b = new byte[8];
            b[7] = (byte) (n & 0xff);
            b[6] = (byte) (n >> 8 & 0xff);
            b[5] = (byte) (n >> 16 & 0xff);
            b[4] = (byte) (n >> 24 & 0xff);
            b[3] = (byte) (n >> 32 & 0xff);
            b[2] = (byte) (n >> 40 & 0xff);
            b[1] = (byte) (n >> 48 & 0xff);
            b[0] = (byte) (n >> 56 & 0xff);
            return b;
        }
    
        /**
         * long类型转byte[] (小端)
         *
         * @param n
         * @return
         */
        public static byte[] long2BytesLittle(long n) {
            byte[] b = new byte[8];
            b[0] = (byte) (n & 0xff);
            b[1] = (byte) (n >> 8 & 0xff);
            b[2] = (byte) (n >> 16 & 0xff);
            b[3] = (byte) (n >> 24 & 0xff);
            b[4] = (byte) (n >> 32 & 0xff);
            b[5] = (byte) (n >> 40 & 0xff);
            b[6] = (byte) (n >> 48 & 0xff);
            b[7] = (byte) (n >> 56 & 0xff);
            return b;
        }
    
        /**
         * byte[]转long类型(小端)
         *
         * @param array
         * @return
         */
        public static long bytes2LongLittle(byte[] array) {
            return ((((long) array[0] & 0xff))
                    | (((long) array[1] & 0xff) << 8)
                    | (((long) array[2] & 0xff) << 16)
                    | (((long) array[3] & 0xff) << 24)
                    | (((long) array[4] & 0xff) << 32)
                    | (((long) array[5] & 0xff) << 40)
                    | (((long) array[6] & 0xff) << 48)
                    | (((long) array[7] & 0xff) << 56));
        }
    
        /**
         * byte[]转long类型(大端)
         *
         * @param array
         * @return
         */
        public static long bytes2LongBig(byte[] array) {
            return ((((long) array[0] & 0xff) << 56)
                    | (((long) array[1] & 0xff) << 48)
                    | (((long) array[2] & 0xff) << 40)
                    | (((long) array[3] & 0xff) << 32)
                    | (((long) array[4] & 0xff) << 24)
                    | (((long) array[5] & 0xff) << 16)
                    | (((long) array[6] & 0xff) << 8)
                    | (((long) array[7] & 0xff)));
        }
    
    
        /**
         * long类型转byte[] (大端),通过ByteArrayOutputStream实现
         *
         * @param l
         * @return
         * @throws IOException
         */
        public static byte[] long2BytesBOS(long l) throws IOException {
            ByteArrayOutputStream bao = new ByteArrayOutputStream();
            DataOutputStream dos = new DataOutputStream(bao);
            dos.writeLong(l);
            byte[] buf = bao.toByteArray();
            return buf;
        }
    
        /**
         * byte[]转long类型(大端),通过ByteArrayOutputStream实现
         *
         * @param data
         * @return
         * @throws IOException
         */
        public long bytes2LongBOS(byte[] data) throws IOException {
            ByteArrayInputStream bai = new ByteArrayInputStream(data);
            DataInputStream dis = new DataInputStream(bai);
            return dis.readLong();
        }
    
        /**
         * long类型转byte[] (大端),通过ByteBuffer实现
         *
         * @param value
         * @return
         */
        public static byte[] long2BytesByteBuffer(long value) {
            return ByteBuffer.allocate(Long.SIZE / Byte.SIZE).putLong(value).array();
        }
    
        /**
         * byte[]转long类型(大端), 通过ByteBuffer实现
         *
         * @param bytes
         * @return
         */
        public static long bytes2LongByteBuffer(byte[] bytes) {
            ByteBuffer buffer = ByteBuffer.allocate(8);
            buffer.put(bytes, 0, bytes.length);
            buffer.flip();
            return buffer.getLong();
        }
    
        /**
         * 将字节数组转为long<br>
         * 如果input为null,或offset指定的剩余数组长度不足8字节则抛出异常
         *
         * @param input        byte[]
         * @param offset       起始偏移量 0
         * @param littleEndian 输入数组是否小端模式
         * @return
         */
        public static long bytes2Long(byte[] input, int offset, boolean littleEndian) {
            long value = 0;
            // 循环读取每个字节通过移位运算完成long的8个字节拼装
            for (int count = 0; count < 8; ++count) {
                int shift = (littleEndian ? count : (7 - count)) << 3;
                value |= ((long) 0xff << shift) & ((long) input[offset + count] << shift);
            }
            return value;
        }
    
        /**
         * 利用 {@link java.nio.ByteBuffer}实现byte[]转long
         *
         * @param input        byte[]
         * @param offset       0
         * @param littleEndian 输入数组是否小端模式
         * @return
         */
        public static long bytes2LongByteBuffer(byte[] input, int offset, boolean littleEndian) {
            // 将byte[] 封装为 ByteBuffer
            ByteBuffer buffer = ByteBuffer.wrap(input, offset, 8);
            if (littleEndian) {
                // ByteBuffer.order(ByteOrder) 方法指定字节序,即大小端模式(BIG_ENDIAN/LITTLE_ENDIAN)
                // ByteBuffer 默认为大端(BIG_ENDIAN)模式
                buffer.order(ByteOrder.LITTLE_ENDIAN);
            }
            return buffer.getLong();
        }
    
        /**
         * int 转 byte
         *
         * @param t
         * @return
         */
        public static byte int2Byte(int t) {
            return (byte) t;
        }
    
        /**
         * byte 转 int,解决java中byte输出可能为负数的问题
         *
         * @param b
         * @return
         */
        public static int byte2Int(byte b) {
            return b & 0xFF;
        }
    
        /**
         * 将 object --> byte 数组
         *
         * @param obj
         * @return
         */
        public static byte[] object2Bytes(Object obj) {
            byte[] bytes = null;
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            try {
                ObjectOutputStream oos = new ObjectOutputStream(bos);
                oos.writeObject(obj);
                oos.flush();
                bytes = bos.toByteArray();
                oos.close();
                bos.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
            return bytes;
        }
    
        /**
         * 数组转对象
         *
         * @param bytes
         * @return
         */
        public Object bytes2Object(byte[] bytes) {
            Object obj = null;
            try {
                ByteArrayInputStream bis = new ByteArrayInputStream(bytes);
                ObjectInputStream ois = new ObjectInputStream(bis);
                obj = ois.readObject();
                ois.close();
                bis.close();
            } catch (IOException | ClassNotFoundException ex) {
                ex.printStackTrace();
            }
            return obj;
        }
    
        /**
         * 两个byte[]是否相同
         * @param data1
         * @param data2
         * @return
         */
        public static boolean bytesEquals(byte[] data1, byte[] data2) {
            return Arrays.equals(data1, data2);
        }
    
        /**
         * 截取byte[]
         * @param data
         * @param position
         * @param length
         * @return
         */
        public static byte[] subBytes(byte[] data, int position, int length) {
            byte[] temp = new byte[length];
            System.arraycopy(data, position, temp, 0, length);
            return temp;
        }
        /**
         * 拼接byte[] 和 byte[]
         *
         * @param bytes1
         * @param bytes2
         * @return
         */
        public static byte[] bytesMerger(byte[] bytes1, byte[] bytes2) {
            byte[] bytes3 = new byte[bytes1.length + bytes2.length];
            System.arraycopy(bytes1, 0, bytes3, 0, bytes1.length);
            System.arraycopy(bytes2, 0, bytes3, bytes1.length, bytes2.length);
            return bytes3;
        }
        /**
         * 拼接byte 和 byte[]
         *
         * @param byte1
         * @param bytes2
         * @return
         */
        public static byte[] bytesMerger(byte byte1, byte[] bytes2) {
            byte[] bytes3 = new byte[1 + bytes2.length];
            bytes3[0] = byte1;
            System.arraycopy(bytes2, 0, bytes3, 1, bytes2.length);
            return bytes3;
        }
    
        /**
         * 拼接byte[] 和 byte
         *
         * @param bytes1
         * @param byte2
         * @return
         */
        public static byte[] bytesMerger(byte[] bytes1, byte byte2) {
            byte[] bytes3 = new byte[1 + bytes1.length];
            System.arraycopy(bytes1, 0, bytes3, 0, bytes1.length);
            bytes3[bytes3.length - 1] = byte2;
            return bytes3;
        }
    
        /**
         * 拼接三个数组
         *
         * @param bt1
         * @param bt2
         * @param bt3
         * @return
         */
        public static byte[] bytesMerger(byte[] bt1, byte[] bt2, byte[] bt3) {
            byte[] data = new byte[bt1.length + bt2.length + bt3.length];
            System.arraycopy(bt1, 0, data, 0, bt1.length);
            System.arraycopy(bt2, 0, data, bt1.length, bt2.length);
            System.arraycopy(bt3, 0, data, bt1.length + bt2.length, bt3.length);
            return data;
        }
    
      /**
         * byte转Hex 16 进制字符串
         */
        public static String byte2Hex(byte b) {
            String hex = Integer.toHexString(b & 0xFF);
            if (hex.length() < 2) {
                hex = "0" + hex;
            }
            return hex;
        }
    
        /**
         * byte[]转Hex
         */
        public static String bytes2Hex(byte[] b) {
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < b.length; i++) {
                String hex = Integer.toHexString(b[i] & 0xFF);
                if (hex.length() < 2) {
                    hex = "0" + hex;
                }
                sb.append(hex.toUpperCase());
            }
            return sb.toString();
        }
    
        /**
         * 字节数组转为16进制字符串
         */
        public static String bytes2Hex2(byte[] bytes) {
            String strHex = "";
            StringBuilder stringBuilder = new StringBuilder();
            for (int n = 0; n < bytes.length; n++) {
                strHex = Integer.toHexString(bytes[n] & 0xFF);
                stringBuilder.append((strHex.length() == 1) ? "0" + strHex : strHex);
            }
            return stringBuilder.toString().trim();
        }
    
        /**
         * Hex转byte,hex只能含两个字符，如果是一个字符byte高位会是0
         */
        public static byte hex2Byte(String hex) {
            return (byte) Integer.parseInt(hex, 16);
        }
    
        /**
         * Hex转byte[]，两种情况，Hex长度为奇数最后一个字符会被舍去
         */
        public static byte[] hex2Bytes(String hex) {
            if (hex.length() < 1) {
                return null;
            } else {
                byte[] result = new byte[hex.length() / 2];
                int j = 0;
                for (int i = 0; i < hex.length(); i += 2) {
                    result[j++] = (byte) Integer.parseInt(hex.substring(i, i + 2), 16);
                }
                return result;
            }
        }
    
        /**
         * 字符串转为16进制字符串，推荐
         */
        public static String str2HexStr(String str) {
            char[] chars = "0123456789ABCDEF".toCharArray();
            StringBuilder sb = new StringBuilder("");
            byte[] bs = str.getBytes();
            int bit;
            for (byte b : bs) {
                bit = (b & 0x0f0) >> 4;
                sb.append(chars[bit]);
                bit = b & 0x0f;
                sb.append(chars[bit]);
            }
            return sb.toString().trim();
        }
    
        /**
         * 16进制直接转换成为字符串(无需Unicode解码)，推荐
         *
         * @param hexStr
         * @return
         */
        public static String hexStr2Str(String hexStr) {
            String str = "0123456789ABCDEF";
            char[] hexs = hexStr.toCharArray();
            byte[] bytes = new byte[hexStr.length() / 2];
            int n;
            for (int i = 0; i < bytes.length; i++) {
                n = str.indexOf(hexs[2 * i]) * 16;
                n += str.indexOf(hexs[2 * i + 1]);
                bytes[i] = (byte) (n & 0xff);
            }
            return new String(bytes);
        }
    
        /**
         * 字符串转换unicode
         */
        public static String string2Unicode(String string) {
            StringBuilder unicode = new StringBuilder();
            for (int i = 0; i < string.length(); i++) {
    // 取出每一个字符
                char c = string.charAt(i);
                // 转换为unicode
                unicode.append("\u").append(Integer.toHexString(c));
            }
            return unicode.toString();
        }
    
        /**
         * unicode 转字符串
         */
        public static String unicode2String(String unicode) {
            StringBuilder string = new StringBuilder();
            String[] hex = unicode.split("\\u");
            for (int i = 1; i < hex.length; i++) {
                // 转换出每一个代码点
                int data = Integer.parseInt(hex[i], 16);
                // 追加成string
                string.append((char) data);
            }
            return string.toString();
        }
    
    }

还有一种写法：

/**
     * <pre>
     *     author : wushaohong
     *     date   : 2020-05-01
     *     desc   : 字节数组与基本数据类型的转换
     *              byte、short、int、float、long、double、16进制字符串
     *     version: 1.0
     * </pre>
     */
    
    public class ByteArrayUtil {
    
        /**
         * 字节数组转 short，小端
         */
        public static short byteArray2Short_Little_Endian(byte[] array) {
    
            // 数组长度有误
            if (array.length > 2) {
                return 0;
            }
    
            short value = 0;
            for (int i = 0; i < array.length; i++) {
                // & 0xff，除去符号位干扰
                value |= ((array[i] & 0xff) << (i * 8));
            }
            return value;
        }
    
        /**
         * 字节数组转 short，大端
         */
        public static short byteArray2Short_Big_Endian(byte[] array) {
    
            // 数组长度有误
            if (array.length > 2) {
                return 0;
            }
    
            short value = 0;
            for (int i = 0; i < array.length ; i++) {
                value |= ((array[i] & 0xff) << ((array.length - i - 1) * 8));
            }
            return value;
        }
    
        /**
         * 字节数组转 int，小端
         */
        public static int byteArray2Int_Little_Endian(byte[] array) {
    
            // 数组长度有误
            if (array.length > 4) {
                return 0;
            }
    
            int value = 0;
            for (int i = 0; i < array.length; i++) {
                value |= ((array[i] & 0xff) << (i * 8));
    
            }
            return value;
        }
    
        /**
         * 字节数组转 int，大端
         */
        public static int byteArray2Int_Big_Endian(byte[] array) {
    
            // 数组长度有误
            if (array.length > 4) {
                return 0;
            }
    
            int value = 0;
            for (int i = 0; i < array.length ; i++) {
                value |= ((array[i] & 0xff) << ((array.length - i - 1) * 8));
            }
            return value;
        }
    
        /**
         * 字节数组转 float，小端
         */
        public static float byteArray2Float_Little_Endian(byte[] array) {
    
            // 数组长度有误
            if (array.length != 4) {
                return 0;
            }
    
            return Float.intBitsToFloat(byteArray2Int_Little_Endian(array));
        }
    
        /**
         * 字节数组转 float，大端
         */
        public static float byteArray2Float_Big_Endian(byte[] array) {
    
            // 数组长度有误
            if (array.length > 4) {
                return 0;
            }
    
            return Float.intBitsToFloat(byteArray2Int_Big_Endian(array));
        }
    
        /**
         * 字节数组转 long，小端
         */
        public static long byteArray2Long_Little_Endian(byte[] array) {
    
            // 数组长度有误
            if (array.length != 8) {
                return 0;
            }
    
            long value = 0;
            for (int i = 0; i < array.length ; i++) {
                // 需要转long再位移，否则int丢失精度
                value |= ((long)(array[i]& 0xff) << (i * 8));
            }
            return value;
        }
    
        /**
         * 字节数组转 long，大端
         */
        public static long byteArray2Long_Big_Endian(byte[] array) {
    
            // 数组长度有误
            if (array.length != 8) {
                return 0;
            }
    
            long value = 0;
            for (int i = 0; i < array.length ; i++) {
                value |= ((long)(array[i] & 0xff) << ((array.length - i - 1) * 8));
            }
            return value;
        }
    
        /**
         * 字节数组转 double，小端
         */
        public static double byteArray2Double_Little_Endian(byte[] array) {
    
            // 数组长度有误
            if (array.length != 8) {
                return 0;
            }
    
            return Double.longBitsToDouble(byteArray2Long_Little_Endian(array));
        }
    
        /**
         * 字节数组转 double，大端
         */
        public static double byteArray2Double_Big_Endian(byte[] array) {
    
            // 数组长度有误
            if (array.length != 8) {
                return 0;
            }
    
            return Double.longBitsToDouble(byteArray2Long_Big_Endian(array));
        }
    
        /**
         * 字节数组转 HexString
         */
        public static String byteArray2HexString(byte[] array) {
    
            StringBuilder builder = new StringBuilder();
            for (byte b : array) {
    
                String s = Integer.toHexString(b & 0xff);
                if (s.length() < 2) {
                    builder.append("0");
                }
                builder.append(s);
            }
    
            return builder.toString().toUpperCase();
        }
    
        //---------------------------------华丽的分割线-------------------------------------
    
        /**
         * short 转字节数组，小端
         */
        public static byte[] short2ByteArray_Little_Endian(short s) {
    
            byte[] array = new byte[2];
    
            for (int i = 0; i < array.length; i++) {
                array[i] = (byte) (s >> (i * 8));
            }
            return array;
        }
    
        /**
         * short 转字节数组，大端
         */
        public static byte[] short2ByteArray_Big_Endian(short s) {
    
            byte[] array = new byte[2];
    
            for (int i = 0; i < array.length; i++) {
                array[array.length - 1 - i] = (byte) (s >> (i * 8));
            }
            return array;
        }
    
        /**
         * int 转字节数组，小端
         */
        public static byte[] int2ByteArray_Little_Endian(int s) {
    
            byte[] array = new byte[4];
    
            for (int i = 0; i < array.length; i++) {
                array[i] = (byte) (s >> (i * 8));
            }
            return array;
        }
    
        /**
         * int 转字节数组，大端
         */
        public static byte[] int2ByteArray_Big_Endian(int s) {
    
            byte[] array = new byte[4];
    
            for (int i = 0; i < array.length; i++) {
                array[array.length - 1 - i] = (byte) (s >> (i * 8));
            }
            return array;
        }
    
        /**
         * float 转字节数组，小端
         */
        public static byte[] float2ByteArray_Little_Endian(float f) {
    
            return int2ByteArray_Little_Endian(Float.floatToIntBits(f));
        }
    
        /**
         * float 转字节数组，大端
         */
        public static byte[] float2ByteArray_Big_Endian(float f) {
    
            return int2ByteArray_Big_Endian(Float.floatToIntBits(f));
        }
    
        /**
         * long 转字节数组，小端
         */
        public static byte[] long2ByteArray_Little_Endian(long l) {
    
            byte[] array = new byte[8];
    
            for (int i = 0; i < array.length; i++) {
                array[i] = (byte) (l >> (i * 8));
            }
            return array;
        }
    
        /**
         * long 转字节数组，大端
         */
        public static byte[] long2ByteArray_Big_Endian(long l) {
    
            byte[] array = new byte[8];
    
            for (int i = 0; i < array.length; i++) {
                array[array.length - 1 - i] = (byte) (l >> (i * 8));
            }
            return array;
        }
    
        /**
         * double 转字节数组，小端
         */
        public static byte[] double2ByteArray_Little_Endian(double d) {
    
            return long2ByteArray_Little_Endian(Double.doubleToLongBits(d));
        }
    
        /**
         * double 转字节数组，大端
         */
        public static byte[] double2ByteArray_Big_Endian(double d) {
    
            return long2ByteArray_Big_Endian(Double.doubleToLongBits(d));
        }
    
        /**
         * HexString 转字节数组
         */
        public static byte[] hexString2ByteArray(String hexString) {
    
            // 两个十六进制字符一个 byte，单数则有误
            if (hexString.length() % 2 != 0) {
                return null;
            }
    
            byte[] array = new byte[hexString.length() / 2];
    
            int value = 0;
            for (int i = 0; i < hexString.length(); i++) {
    
                char s = hexString.charAt(i);
    
                // 前半个字节
                if (i % 2 == 0) {
                    value = Integer.parseInt(String.valueOf(s), 16) * 16;
                } else {
                    // 后半个字节
                    value += Integer.parseInt(String.valueOf(s), 16);
                    array[i / 2] = (byte) value;
                    value = 0;
                }
            }
    
            return array;
        }
    }

参考

[Java 中 byte、byte 数组和 int、long 之间的转换][Java _ byte_byte _ int_long]

[大端小端模式][Link 2]

[Link 1]: https://link.juejin.cn?target=https%3A%2F%2Fwww.cnblogs.com%2Flittle-white%2Fp%2F3236548.html
[Java _ byte_byte _ int_long]: https://link.juejin.cn/?target=https%3A%2F%2Fblog.csdn.net%2Fdefonds%2Farticle%2Fdetails%2F8782785
[Link 2]: https://link.juejin.cn/?target=https%3A%2F%2Fblog.csdn.net%2Fu011368551%2Farticle%2Fdetails%2F113874060