Java如何优雅解析字节数组为对象或把对象转字节数组

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二通常的解析方式

通常情况下，针对这种数据，我们可能会对每个记录类型中的每个字段一个一个字段读取，然后处理这些记录类型数据的地方，到处都是写了很多的读取逻辑，如下：

/**  
 * 充电桩实时数据上传 * @param scuProtocolBody  
 */  
private void pileRealtime(ScuProtocolBody scuProtocolBody) {  
    log.info("收到充电桩实时数据!data:{}", scuProtocolBody.getData());  
    String data = scuProtocolBody.getData();  
    int startIndex = 0;  
    int endIndex = TRAN_SN_BYTES * 2;  
    String tranSn = data.substring(startIndex, endIndex);  
  
    startIndex = endIndex;  
    endIndex = startIndex + PILESN_BYTES * 2;  
    String pileSn = data.substring(startIndex, endIndex);  
  
    startIndex = endIndex;  
    endIndex = startIndex + GUNID_BYTES * 2;  
    String gunSn = data.substring(startIndex, endIndex);  
  
    startIndex = endIndex;  
    endIndex = startIndex + RESULT_BYTES * 2;  
    int gunStatus = StringUtils.hexToInt(data.substring(startIndex, endIndex));  
    PileOrderRealtimeVO realtimeVO = new PileOrderRealtimeVO().setTranSn(tranSn).setPileSn(pileSn).setGunSn(gunSn).setGunStatus(gunStatus);  
    if (GunStatusEnum.CHARGING.getCode() == gunStatus){  
        //如果是充电中,就需要把充电交易数据送到运营中心  
        startIndex = endIndex + 2 * 2; //跳过了"枪是否归位"和"是否插枪"的协议中不取的字节数  
        endIndex = startIndex + TWO_BYTES * 2;  
        int outVoltInt = StringUtils.hexToIntEndian(data.substring(startIndex, endIndex));  
        double outVolt = DoubleUtil.intToDoubleForMagn(outVoltInt, 10);  
  
        startIndex = endIndex;  
        endIndex = startIndex + TWO_BYTES * 2;  
        int outElecInt = StringUtils.hexToIntEndian(data.substring(startIndex, endIndex));  
        double outElec = DoubleUtil.intToDoubleForMagn(outElecInt, 10);  
  
        startIndex = endIndex + 9 * 2; //跳过了"枪线温度"和"枪线编码"的协议中不取的字节数  
        endIndex = startIndex + ONE_BYTES * 2;  
        int soc = StringUtils.hexToIntEndian(data.substring(startIndex, endIndex));  
  
        startIndex = endIndex + ONE_BYTES * 2; //跳过了协议中"电池组最高温度"不取的字节数  
        endIndex = startIndex + DATE_MIN_BYTES * 2;  
        int totalChargeTime = StringUtils.hexToIntEndian(data.substring(startIndex, endIndex));  
        //剩余充电时间  
        startIndex = endIndex ;  
        endIndex = startIndex + DATE_MIN_BYTES * 2;  
        int residueChargeTime = StringUtils.hexToIntEndian(data.substring(startIndex, endIndex));  
        //充电度数  
        startIndex = endIndex ;  
        endIndex = startIndex + FOUR_BYTES * 2;  
        int chargeDegInt = StringUtils.hexToIntEndian(data.substring(startIndex, endIndex));  
        double chargeDeg = DoubleUtil.intToDoubleForMagn(chargeDegInt, 10000);  
        //计损充电度数  
        startIndex = endIndex ;  
        endIndex = startIndex + FOUR_BYTES * 2;  
        int meterLossChargeDegInt = StringUtils.hexToIntEndian(data.substring(startIndex, endIndex));  
        double meterLossChargeDeg = DoubleUtil.intToDoubleForMagn(meterLossChargeDegInt, 10000);  
        //已充金额  
        startIndex = endIndex ;  
        endIndex = startIndex + FOUR_BYTES * 2;  
        int chargeAmountInt = StringUtils.hexToIntEndian(data.substring(startIndex, endIndex));  
        double chargeAmount = DoubleUtil.intToDoubleForMagn(chargeAmountInt, 10000);  
        //充电枪告警码  
        startIndex = endIndex ;  
        endIndex = startIndex + EIGHT_BYTES * 2;  
        //经历时段个数  
        startIndex = endIndex ;  
        endIndex = startIndex + ONE_BYTES * 2;  
        int timeFrameNum = StringUtils.hexToIntEndian(data.substring(startIndex, endIndex));  
        double totolElecFee = 0D;  
        double totolServiceFee = 0D;  
        for (int i = 1; i <= timeFrameNum; i++) {  
            startIndex = endIndex ;  
            endIndex = startIndex + (FOUR_BYTES + EIGHT_BYTES) * 2;//开始时间,结束时间,服务费单价,电费单价,总电量  
            startIndex = endIndex ;  
            endIndex = startIndex + (FOUR_BYTES) * 2;//总电费  
            int elecFeeInt = StringUtils.hexToIntEndian(data.substring(startIndex, endIndex));  
            double elecFee = DoubleUtil.intToDoubleForMagn(elecFeeInt, 10000);  
            totolElecFee += elecFee;  
            startIndex = endIndex ;  
            endIndex = startIndex + (FOUR_BYTES) * 2;//总服务费  
            int serviceFeeInt = StringUtils.hexToIntEndian(data.substring(startIndex, endIndex));  
            double serviceFee = DoubleUtil.intToDoubleForMagn(serviceFeeInt, 10000);  
            totolServiceFee += serviceFee;  
        }  
        realtimeVO.setOutVolt(outVolt).setOutElec(outElec).setSoc(soc).setTotalChargeTime(totalChargeTime).setResidueChargeTime(residueChargeTime).setChargeDeg(chargeDeg)  
                .setMeterLossChargeDeg(meterLossChargeDeg).setChargeAmount(chargeAmount).setElecFee(DoubleUtil.get4Point(totolElecFee)).setServiceFee(DoubleUtil.get4Point(totolServiceFee));  
    }  
    miniAppChargeOptService.chargeRealTime(realtimeVO);  
}

以上这些代码，是对我们桩协议中信息体部分的解析代码，看了以上这段代码，不知道你是一种什么感觉，我就问你易读性如何？如果要修改容易改吗？

如果协议都是标准的，只需要解析这么一次，这样做其实问题也不大，关键是，要对接的记录类型至少十多个，每个都这么写，容不容易出错？出错后容不容易检查定位？

三优雅的解析或转字节数组做法

通过反射机制和自定义注解方式，做到优雅的读取和对象转字节数组。具体方式如下：

自定义注解

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * 字段字节类型
 *
 * @author mafgwo
 * @since 2022/10/20
 */
@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ByteType {

    /**
     * 字节长度
     * @return
     */
    int len() default 0;

    /**
     * 长度字段
     * @return
     */
    String lenField() default "";

    /**
     * 小数个数




    

     * @return
     */
    int decimalNum() default 0;

    /**
     * 偏移量 转字节时 减去偏移 转对象时 加上偏移
     * @return
     */
    int offset() default 0;

    /**
     * ASCII编码标识 针对String 0 非ascii 1 小端序 2 大端序
     * @return
     */
    int asciiFlag() default 0;

}

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * 字段字节列表类型
 *
 * @author mafgwo
 * @since 2022/10/20
 */
@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ListType {

    /**
     * 对象数对应的字段
     * @return
     */
    String itemNumField();

}

写转换工具类

import com.mafgwo.annotation.ByteType;
import com.mafgwo.annotation.ListType;
import lombok.Data;
import lombok.experimental.Accessors;
import lombok.extern.slf4j.Slf4j;
import org.springframework.util.Assert;

import java.io.ByteArrayOutputStream;
import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;

/**
 * 记录类型工具类
 *
 * @author mafgwo
 * @since 2022/10/20
 */
@Slf4j
public class RecordDataUtils {

    private RecordDataUtils() {
    }

    /**
     * 云端字节转对象
     * @param bytes
     * @param cls
     * @param <T>
     * @return
     */
    public static <T> T cloudConvertToObj(byte[] bytes, Class<T> cls) {
        return




    
 convertToObj(new ByteAndIdx().setBytes(bytes).setIdx(0), cls, true);
    }


    /**
     * 云端对象转字节
     * @param obj
     * @return
     */
    public static byte[] cloudConvertToBytes(Object obj) {
        return convertToBytes(obj, true, null);
    }

    /**
     * 本地16进制字符串转对象
     * @param hexData
     * @param cls
     * @param <T>
     * @return
     */
    public static <T> T localConvertToObj(String hexData, Class<T> cls) {
        return convertToObj(new ByteAndIdx().setBytes(ByteUtil.toBytesFromHexString(hexData)).setIdx(0), cls, false);
    }

    /**
     * 本地对象转16进制字符串
     * @param obj
     * @return
     */
    public static String localConvertToHexString(Object obj) {
        byte[] bytes = convertToBytes(obj, false, null);
        return ByteUtil.byteArrayToHexString(bytes);
    }

    /**
     * 字节转换为对象
     *
     * @param byteAndIdx
     * @param cls
     * @param <T>
     * @return
     */
    public static <T> T convertToObj(ByteAndIdx byteAndIdx, Class<T> cls, boolean bcdReverse) {
        byte[] bytes = byteAndIdx.getBytes();
        List<Field> declaredFields = ClassUtil.getAllFields(cls);
        try {
            // 数字类型的字段名与值映射
            Map<String, Number> fieldNameValMap = new HashMap<>();
            T obj = cls.newInstance();
            for (Field declaredField : declaredFields) {
                declaredField.setAccessible(true);
                int len = 0;
                int offset = 0;
                ByteType annotation = declaredField.getDeclaredAnnotation(ByteType.class);
                if (annotation != null) {
                    len = annotation.len();
                    offset = annotation.offset();
                    if (!"".equals(annotation.lenField())) {
                        Number number = fieldNameValMap.get(annotation.lenField());
                        Assert.notNull(number, "ByteType注解中的" + annotation.lenField() + "属性未找到值");
                        len = number.intValue();
                    }
                    if (len <= 0) {
                        continue;
                    }
                }
                Object val = null;
                // 如果是字节则直接取第一个字节
                if (declaredField.getType() == Byte.class) {
                    val = (byte) (bytes[byteAndIdx.idx++] + offset);
                    fieldNameValMap.put(declaredField.getName(), (Number) val);
                }
                // Short 2个字节
                else if (declaredField.getType() == Short.class) {
                    val = (short) (ByteUtil.byteArrayToShort(ByteUtil.getByte(bytes, byteAndIdx.idx, 2)) + offset);
                    byteAndIdx.idx += 2;
                    fieldNameValMap.put(declaredField.getName(), (Number) val);
                }
                // Integer 4个字节
                else if (declaredField.getType() == Integer.class) {
                    val = ByteUtil.byteArrayToInt(ByteUtil.getByte(bytes, byteAndIdx.idx, 4)) + offset;
                    byteAndIdx.idx += 4;
                    fieldNameValMap.put(declaredField.getName(), (Number) val);
                }
                // Long 8个字节
                else if (declaredField.getType() == Long.class) {
                    val = ByteUtil.byteArrayToLong(ByteUtil.getByte(bytes, byteAndIdx.idx, 8)) + offset;
                    byteAndIdx.idx += 8;
                    fieldNameValMap.put(declaredField.getName(), (Number) val);
                }
                // Float或Double类型
                else if (declaredField.getType() == Float.class || declaredField.getType() == Double.class) {
                    Assert.notNull(annotation, "Float/Double类型属性必须包含ByteType注解");
                    double v = ByteUtil.byteArrayToLong(ByteUtil.getByte(bytes, byteAndIdx.idx, len)) / Math.pow(10, annotation.decimalNum());
                    if (declaredField.getType() == Float.class) {
                        val = (float) (v + offset);
                    } else {
                        val = v + offset;
                    }
                    byteAndIdx.idx += len;
                }
                // 时间类型
                else if (declaredField.getType() == Date.class) {
                    val = ByteUtil.byte2Hdate(ByteUtil.getByte(bytes, byteAndIdx.idx, 7));
                    byteAndIdx.idx += 7;
                }
                // 字符串类型
                else if (declaredField.getType() == String.class) {
                    Assert.notNull(annotation, "String类型属性必须包含ByteType注解");
                    // 如果是ascii编码
                    if (annotation.asciiFlag() == 1) {
                        val = ByteUtil.toAsciiFromBytes(ByteUtil.getByte(bytes, byteAndIdx.idx, len), false);
                    }
                    else if (annotation.asciiFlag() == 2) {
                        val = ByteUtil.toAsciiFromBytes(ByteUtil.getByte(bytes, byteAndIdx.idx, len), true);
                    } else {
                        val = Util.byteArray2HexString(ByteUtil.getByte(bytes, byteAndIdx.idx, len), Integer.MAX_VALUE, false, bcdReverse);
                    }
                    byteAndIdx.idx += len;
                }
                // List类型
                else if (declaredField.getType() == List.class) {
                    ListType listType = declaredField.getDeclaredAnnotation(ListType.class);
                    Assert.notNull(listType, "List类型属性必须包含ListType注解");
                    Number itemNum = fieldNameValMap.get(listType.itemNumField());
                    Assert.notNull(itemNum, "List类型注解中的" + listType.itemNumField() + "属性未找到值");
                    // 如果是List类型，得到其Generic的类型
                    Type genericType = declaredField.getGenericType();
                    Assert.notNull(genericType, "List类型的泛型类型不允许为空");
                    Assert.isTrue(genericType instanceof ParameterizedType, "List类型的泛型类型必须是自定义对象");
                    Class<?> genericClazz = (Class<?>) ((ParameterizedType) genericType).getActualTypeArguments()[0];
                    List list = new ArrayList(itemNum.intValue());
                    for (int i = 0; i < itemNum.intValue(); i++) {
                        list.add(convertToObj(byteAndIdx, genericClazz, bcdReverse));
                    }
                    val = list;
                }
                declaredField.set(obj, val);
            }
            return obj;
        } catch (Exception e) {
            log.error("字节转换为对象异常,bytes:{}", ByteUtil.byteArrayToHexString(bytes), e);
            return null;
        }
    }

    /**
     * 对象转字节 如果字段为null直接用FF填充
     *
     * @param obj
     * @param bcdReverse
     * @param fieldName  字段名称 没有则是所有字段
     * @return
     */
    public static byte[] convertToBytes(Object obj, boolean bcdReverse, String fieldName) {
        try {
            // 数字类型的字段名与值映射
            Map<String, Number> fieldNameValMap = new HashMap<>();
            ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
            List<Field> declaredFields = ClassUtil.getAllFields(obj.getClass());
//            int curr = 0;
            // 数字类型的字段名与值映射
            for (Field declaredField : declaredFields) {
                // 如果有传入字段名 字段名不匹配则跳过
                if (fieldName != null && !Objects.equals(declaredField.getName(), fieldName)) {
                    continue;
                }
                declaredField.setAccessible(true);
                Object val = declaredField.get(obj);
                ByteType annotation = declaredField.getDeclaredAnnotation(ByteType.class);
                int len = 0;
                int offset = 0;
                if (annotation != null) {
                    len = annotation.len();
                    offset = annotation.offset();
                    if (!"".equals(annotation.lenField())) {
                        Number number = fieldNameValMap.get(annotation.lenField());
                        Assert.notNull(number, "ByteType注解中的" + annotation.lenField() + "属性未找到值"




    
);
                        len = number.intValue();
                    }
                    if (len <= 0) {
                        continue;
                    }
                }
                // 如果是字节则直接取第一个字节
                if (declaredField.getType() == Byte.class) {
                    outputStream.write(val != null ? ((byte) val) - offset : 0xFF);
                    fieldNameValMap.put(declaredField.getName(), (Number) val);
                }
                // Short 2个字节
                else if (declaredField.getType() == Short.class) {
                    outputStream.write(val != null ? ByteUtil.shortToByteArray((short) ((short) val - offset)) : ByteUtil.get0xFFBytes(2));
                    fieldNameValMap.put(declaredField.getName(), (Number) val);
                }
                // Integer 4个字节
                else if (declaredField.getType() == Integer.class) {
                    outputStream.write(val != null ? ByteUtil.intToByteArray((int) val - offset) : ByteUtil.get0xFFBytes(4));
                    fieldNameValMap.put(declaredField.getName(), (Number) val);
                }
                // Long 8个字节
                else if (declaredField.getType() == Long.class) {
                    outputStream.write(val != null ? ByteUtil.longToByteArray((long) val - offset) : ByteUtil.get0xFFBytes(8));
                    fieldNameValMap.put(declaredField.getName(), (Number) val);
                }
                // Float或Double类型
                else if (declaredField.getType() == Float.class || declaredField.getType() == Double.class) {
                    Assert.notNull(annotation, "Float/Double类型属性必须包含ByteType注解");
                    if (val == null) {
                        outputStream.write(ByteUtil.get0xFFBytes(len));
                    } else {
                        long v = Math.round((((Number) val).doubleValue() - offset) * Math.pow(10, annotation.decimalNum()));
                        outputStream.write(ByteUtil.longToByteArray(v, len));
                    }
                }
                // 时间类型
                else if (declaredField.getType() == Date.class) {
                    if (val == null) {
                        outputStream.write(ByteUtil.get0xFFBytes(7));
                    } else {
                        byte[] v = ByteUtil.date2Hbyte((Date) val);
                        outputStream.write(v);
                    }
                }
                // 字符串类型
                else if (declaredField.getType() == String.class) {
                    Assert.notNull(annotation, "String类型属性必须包含ByteType注解");
                    if (val == null) {
                        outputStream.write(ByteUtil.get0xFFBytes(len));
                    } else {
                        int length = ((String) val).length() / 2;
                        Assert.isTrue(len >= length, "字符串长度超过ByteType注解中定义长度");
                        // bcdReverse 反向为前补0
                        if ((annotation.asciiFlag() == 2 || bcdReverse) && len > length ) {
                            outputStream.write(ByteUtil.getZeroBytes(len - length));
                        }
                        // 如果是ascii编码
                        if (annotation.asciiFlag() > 0) {
                            outputStream.write(ByteUtil.toBytesFromAscii((String)val));
                        } else {
                            outputStream.write(ByteUtil.toBytesFromHexString((String)val, bcdReverse));
                        }
                        // bcdReverse 正向为后补0
                        if (!(annotation.asciiFlag() == 2 || bcdReverse) && len > length ) {
                            outputStream.write(ByteUtil.getZeroBytes(len - length));
                        }
                    }
                }
                // List类型
                else if (declaredField.getType() == List.class) {
                    List list = (List) val;
                    for (Object item : list) {
                        byte[] itemBytes = convertToBytes(item, bcdReverse, fieldName);
                        Assert.notNull(itemBytes, "记录对象子项转字节为null,item:" + item);
                        outputStream.write(itemBytes);
                    }
                }
                if (fieldName != null && Objects.equals(declaredField.getName(), fieldName)) {
                    break;
                }
//                log.info("----------------{}:{}", declaredField.getName(), outputStream.size() - curr);
//                curr = outputStream.size();
            }
            return outputStream.toByteArray();
        } catch (Exception e) {
            log.error("对象转换为字节数组异常,obj:{}", obj, e);
            return null;
        }
    }

    @Accessors(chain = true)
    @Data
    public static class ByteAndIdx {
        private byte[] bytes;
        private int idx;
    }

}

依赖的其他工具类

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

/**
 * 类工具类
 *
 * @author mafgwo
 * @since 2022/10/21
 */
public class ClassUtil {

    private ClassUtil() {
    }

    /**
     * 获取所有的属性（含父类属性）
     *
     * @param cls
     * @return
     */
    public static List<Field> getAllFields(Class<?> cls) {
        if (cls == Object.class) {
            return Collections.emptyList();
        }
        Field[] declaredFields = cls.getDeclaredFields();
        Class<?> genericSuperclass = (Class<?>) cls.getGenericSuperclass();
        if (genericSuperclass == Object.class) {
            return Arrays.asList(declaredFields);
        } else {
            List<Field> genericFields = getAllFields(genericSuperclass);
            List<Field> allFields = new ArrayList<>(genericFields.size() + declaredFields.length);
            allFields.addAll(genericFields);
            allFields.addAll(Arrays.asList(declaredFields));
            return allFields;
        }
    }
}

import org.springframework.util.StringUtils;

import java.io.ByteArrayOutputStream;
import java.nio.charset.StandardCharsets;
import java.util.Calendar;
import java.util.Date;

/**
 * byte 工具类
 *
 * @author mafgwo
 * @since 2022/09/30
 */
public class ByteUtil {

    /**
     * @param @param  i
     * @param @return
     * @return byte[]
     * @throws
     * @Title: intToByteArray
     * @Description: int 转换成 byte数组
     */
    public static byte[] longToByteArray(long val) {
        return longToByteArray(val, 8);
    }

    public static byte[] longToByteArray(long val, int len) {
        byte[] result = new byte[len];
        for (int i = 0; i < result.length; i++) {
            result[i] = (byte) (val >> (i * 8) & 0xFF);
        }
        return result;
    }

    /**
     * @param @param  i
     * @param @return
     * @return byte[]
     * @throws
     * @Title: intToByteArray
     * @Description: int 转换成 byte数组
     */
    public static byte[] intToByteArray(int i) {
        byte[] result = new byte[4];
        result[3] = (byte) ((i >> 24) & 0xFF);
        result[2] = (byte) ((i >> 16) & 0xFF);
        result[1] = (byte) ((i >> 8) & 0xFF);
        result[0] = (byte) (i & 0xFF);
        return result;
    }

    /**
     * @param @param  val
     * @param @return
     * @return byte[]
     * @throws
     * @Title: shortToByteArray
     * @Description: short 转换成 byte[]
     */
    public static byte[] shortToByteArray(short val) {
        byte[] b = new byte[2];
        b[1] = (byte) ((val >> 8) & 0xff);
        b[0] = (byte) (val & 0xff);
        return b;
    }

    /**
     * @param @param  bytes
     * @param




    
 @return
     * @return int
     * @throws
     * @Title: byteArrayToInt
     * @Description: byte[] 转换成 int
     */
    public static int byteArrayToInt(byte[] bytes) {
        int value = 0;
        for (int i = 0; i < bytes.length; i++) {
            int shift = i * 8;
            value += (bytes[i] & 0xFF) << shift;
        }
        return value;
    }

    /**
     * @param @param  bytes
     * @param @return
     * @return int
     * @throws
     * @Title: byteArrayToInt
     * @Description: byte[] 转换成 int
     */
    public static long byteArrayToLong(byte[] bytes) {
        int value = 0;
        for (int i = 0; i < bytes.length; i++) {
            int shift = i * 8;
            value += (bytes[i] & 0xFF) << shift;
        }
        return value;
    }

    /**
     * @param @param  bytes
     * @param @return
     * @return short
     * @throws
     * @Title: byteArrayToShort
     * @Description: byte[] 转换成short
     */
    public static short byteArrayToShort(byte[] bytes) {
        short value = 0;
        for (int i = 0; i < 2; i++) {
            int shift = i * 8;
            value += (bytes[i] & 0xFF) << shift;
        }
        return value;
    }

    /**
     * @param @param  date
     * @param @return
     * @return byte[]
     * @throws
     * @Title: date2HByte
     * @Description: 日期转换成 CP56Time2a
     */
    public static byte[] date2Hbyte(Date date) {
        ByteArrayOutputStream bOutput = new ByteArrayOutputStream();
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        // 毫秒需要转换成两个字节其中 低位在前高位在后 
        // 先转换成short
        int millisecond = calendar.get(Calendar.SECOND) * 1000 + calendar.get(Calendar.MILLISECOND);

        // 默认的低位在前
        byte[] millisecondByte = intToByteArray(millisecond);
        bOutput.write(millisecondByte[0]);
        bOutput.write(millisecondByte[1]);

        // 分钟 只占6个比特位 需要把前两位置为零 
        bOutput.write((byte) calendar.get(Calendar.MINUTE));
        // 小时需要把前三位置零
        bOutput.write((byte) calendar.get(Calendar.HOUR_OF_DAY));
        // 星期日的时候 week 是0 
        int week = calendar.get(Calendar.DAY_OF_WEEK);
        if (week == Calendar.SUNDAY) {
            week = 7;
        } else {
            week--;
        }
        // 前三个字节是 星期 因此需要将星期向左移5位  后五个字节是日期  需要将两个数字相加 相加之前需要先将前三位置零
        bOutput.write((byte) (week << 5) + (calendar.get(Calendar.DAY_OF_MONTH)));
        // 前四字节置零
        bOutput.write((byte) ((byte) calendar.get(Calendar.MONTH) + 1));
        bOutput.write((byte) (calendar.get(Calendar.YEAR) - 2000));
        return bOutput.toByteArray();
    }


    /**
     * @param @param  date
     * @param @return
     * @return byte[]
     * @throws
     * @Title: date2HByte
     * @Description:CP56Time2a转换成 时间
     */
    public static Date byte2Hdate(byte[] dataByte) {
        int year = (dataByte[6] & 0x7F) + 2000;
        int month = dataByte[5] & 0x0F;
        int day = dataByte[4] & 0x1F;
        int hour = dataByte[3] & 0x1F;
        int minute = dataByte[2] & 0x3F;
        int second = dataByte[1] > 0 ? dataByte[1] : (int) (dataByte[1] & 0xff);
        int millisecond = dataByte[0] > 0 ? dataByte[0] : (int) (dataByte[0] & 0xff);
        millisecond = (second << 8) + millisecond;
        second = millisecond / 1000;
        millisecond = millisecond % 1000;
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.YEAR, year);
        calendar.set(Calendar.MONTH, month - 1);
        calendar.set(Calendar.DAY_OF_MONTH, day);
        calendar.set(Calendar.HOUR_OF_DAY, hour);
        calendar.set(Calendar.MINUTE, minute);
        calendar.set(Calendar.SECOND, second);
        calendar.set(Calendar.MILLISECOND, millisecond);
        return calendar.getTime();
    }

    public static String byteArrayToHexString(byte[] array) {
        return Util.byteArray2HexString(array, Integer.MAX_VALUE, false);
    }

    public static String reverseByteArrayToHexString(byte[] array) {
        return Util.byteArray2HexString(array, Integer.MAX_VALUE, false, true);
    }

    public static String byteArrayToHexString(byte[] array, boolean blank) {
        return Util.byteArray2HexString(array, Integer.MAX_VALUE, blank);
    }

    /**
     * 将16进制字符串转换为byte[]
     *
     * @param str
     * @return
     */
    public static byte[] toBytesFromHexString(String str) {
        return toBytesFromHexString(str, false);
    }

    /**
     * 将16进制字符串转换为byte[] byte倒序
     * 南网电动的 桩编号 交易流水号等都是倒序的
     * @param str
     * @return
     */
    private static byte[] toReverseBytesFromHexString(String str) {
        return toBytesFromHexString(str, true);
    }

    /**
     * 将16进制字符串转换为byte[]
     *
     * @param str
     * @param reverse 是否倒序 true 倒序 则前面的转为高位 后面的转为低位
     * @return
     */
    public static byte[] toBytesFromHexString(String str, boolean reverse) {
        if (StringUtils.isEmpty(str)) {
            return new byte[0];
        }
        int byteLen = str.length() / 2;
        byte[] bytes = new byte[byteLen];
        for (int i = 0; i < byteLen; i++) {
            String subStr = str.substring(i * 2, i * 2 + 2);
            int index = reverse ? byteLen - 1 - i : i;
            bytes[index] = (byte) Integer.parseInt(subStr, 16);
        }
        return bytes;
    }

    /**
     * 返回指定位置的数组
     *
     * @param bytes
     * @param




    
 start  开始位置
     * @param length 截取长度
     * @return
     */
    public static byte[] getByte(byte[] bytes, int start, int length) {
        length = Math.min(length, bytes.length - start);
        byte[] ruleByte = new byte[length];
        int index = 0;
        while (index < length) {
            ruleByte[index++] = bytes[start++];
        }
        return ruleByte;
    }

    /**
     * 校验指定的数组是否都是0 是则返回true 否则false
     *
     * @param bytes
     * @param start  开始位置
     * @param length 截取长度
     * @return
     */
    public static boolean validBytesZero(byte[] bytes, int start, int length) {
        length = Math.min(length, bytes.length - start);
        int index = 0;
        while (index < length) {
            if (bytes[start++] != 0) {
                return false;
            }
            index++;
        }
        return true;
    }

    /**
     * 16进制转10进制
     * @param hex 16进制字符串
     * @return
     */
    public static int hexToInt(String hex) {
        return Integer.parseInt(hex, 16);
    }

    /**
     * 16进制转10进制
     * @param hex 16进制字符串
     * @return
     */
    public static long hexToLong(String hex) {
        return Long.parseLong(hex, 16);
    }


    /**
     * 整数转16进制字符串
     * @param intVal 整数值
     * @param byteLen 转换后的总字节数
     * @param littleEndian true=小端序 false=大端序
     * @return
     */
    public static String intToHex(Integer intVal, int byteLen, boolean littleEndian) {
        String hex = Integer.toHexString(intVal).toUpperCase();
        int finalLen = byteLen * 2;
        int diff = finalLen - hex.length();
        StringBuilder sb = new StringBuilder(finalLen);
        for (int i = 0; i < diff; i++) {
            sb.append("0");
        }
        sb.append(hex);
        if (!littleEndian) {
            return sb.toString();
        }
        else {
            return transferEndian(sb.toString());
        }
    }

    /**
     * 转换大小端
     * @param hex 16进制字符串
     * @return
     */
    public static String transferEndian(String hex) {
        StringBuilder sb = new StringBuilder(hex.length());
        for (int i = hex.length(); i > 0; i -= 2) {
            sb.append(hex.substring(i - 2, i));
        }
        return sb.toString();
    }

    /**
     * float类型转4字节数组
     * @param fval
     * @param remain
     * @return
     */
    public static byte[] floatToBytes(float fval, int remain) {
        int bits = (int) (fval * Math.pow(10, remain));
        return intToByteArray(bits);
    }

    /**
     * float类型转2字节数组
     * @param fval
     * @return
     */
    public static byte[] floatToShortBytes(float fval, int remain) {
        short bits = (short) (fval * Math.pow(10, remain));
        return shortToByteArray(bits);
    }

    /**
     * 创建为0的字节
     * @param length
     * @return
     */
    public static byte[] getZeroBytes(int length) {
        byte[] bytes = new byte[length];
        for (int i = 0; i < length; i++) {
            bytes[i] = 0;
        }
        return bytes;
    }

    /**
     * 创建为FF的字节
     * @param length
     * @return
     */
    public static byte[] get0xFFBytes(int length) {
        byte[] bytes = new byte[length];
        for (int i = 0; i < length; i++) {
            bytes[i] = (byte) 0xFF;
        }
        return bytes;
    }

    /**
     * 字节转ASCII 结束符为 00
     * @param bytes
     * @param reverse
     * @return
     */
    public static String toAsciiFromBytes(byte[] bytes, boolean reverse) {
        if (bytes.length == 0) {
            return "";
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < bytes.length; i++) {
            int idx = reverse ? bytes.length - 1 - i : i;
            if (bytes[idx] == 0) {
                break;
            }
            sb.append((char) bytes[idx]);
        }
        return sb.toString();
    }

    /**
     * 字节转ASCII
     * @param str
     * @return
     */
    public static byte[] toBytesFromAscii(String str) {
        byte[] bytes = new byte[str.length()];
        for (int i = 0; i < str.length(); i++) {
            bytes[i] = (byte) str.charAt(i);
        }
        return bytes;
    }

    public static byte[] mergeBytes(byte[] bytes1, byte[] bytes2) {
        byte[] bytes = new byte[bytes1.length + bytes2.length];
        System.arraycopy(bytes1, 0, bytes, 0, bytes1.length);
        System.arraycopy(bytes2, 0, bytes, bytes1.length, bytes2.length);
        return bytes;
    }

}

编写信息体中含记录类型和业务数据的信息对象


/**
 * 云端计费模型
 * [1] 下发记录类型
 * [2-9] 充电设备编号 压缩 BCD 码 8Byte 充电设备编号
 * [10] 充电接口标识 BIN 码 1Byte 充电设备为一桩多充时用来标记接口号，一桩一充时此项为0。多个接口时顺序对每个接口进行编号
 * [11-18] 计费模型 ID BIN 码 8Byte 运营管理系统产生
 * [19-25] 生效时间 BIN 码 7Byte CP56Time2a 格式
 * [26-32] 失效时间 BIN 码 7Byte CP56Time2a 格式
 * [33-34] 执行状态 压缩 BCD 码 2Byte 0001-有效 0002-无效
 * [35-36] 计量类型 压缩 BCD 码 2Byte 0001-充电量
 * [37] 时段数 N BIN 码 1Byte 取值范围：0—12
 * [38-39] 第 1 个时段起始时间点 BIN 码 2Byte 高字节：小时（0-24）低字节：分钟（0-60）
 * [40] 第 1 个时段标志 BIN 码 1Byte 1：尖时段；2：峰时段 3：平时段，4：谷时段
 * [41-44] 第 1 个尖时段尖电价 BIN 码 4Byte 精确到小数点后五位
 * [45-48] 第 1 个峰时段电价 BIN 码 4Byte 精确到小数点后五位
 * [49-52] 第 1 个平时段电价 BIN 码 4Byte 精确到小数点后五位
 * [53-56] 第 1 个谷时段电价 BIN 码 4Byte 精确到小数点后五位
 * [57-60] 第 1 个服务费单价 BIN 码 4Byte 精确到小数点后五位
 * [61-64] 第 1 个占位费单价 BIN 码 4Byte 精确到小数点后五位
 * [65-68] 第 1 个预约费单价 BIN 码 4Byte 精确到小数点后五位
 * @author mafgwo
 * @since 2022/10/20
 */
@EqualsAndHashCode(callSuper = true)
@ToString(callSuper = true)
@Data
public class CloudFeeModeVO extends RecordBaseVO {
    /**
     * 下发数据类型
     */
    private Byte recordType;

    /**
     * 充电设备编号
     */
    @ByteType(len = 8)
    private String cloudPileSn;

    /**
     * 充电接口标识
     */
    private Byte gunNo;

    /**
     * 计费模型ID
     */
    private Long feeModeId;

    /**
     * 生效时间
     */
    private Date activeTime;
    /**
     * 失效时间
     */
    private Date inActiveTime;

    /**
     * 执行状态 0001-有效 0002-无效
     */
    @ByteType(len = 2)
    private String execStatus;

    /**
     * 计量类型
     */
    @ByteType(len = 2)
    private String measureType;

    /**
     * 时段数
     */
    private Byte periodNum;

    /**
     * 时段
     */
    @ListType(itemNumField = "periodNum")
    private List<PeriodVO> periods;

    /**
     * [38-39] 第 1 个时段起始时间点 BIN 码 2Byte 高字节：小时（0-24）低字节：分钟（0-60）
     * [40] 第 1 个时段标志 BIN 码 1Byte 1：尖时段；2：峰时段 3：平时段，4：谷时段
     * [41-44] 第 1 个尖时段尖电价 BIN 码 4Byte 精确到小数点后五位
     * [45-48] 第 1 个峰时段电价 BIN 码 4Byte 精确到小数点后五位
     * [49-52] 第 1 个平时段电价 BIN 码 4Byte 精确到小数点后五位
     * [53-56] 第 1 个谷时段电价 BIN 码 4Byte 精确到小数点后五位
     * [57-60] 第 1 个服务费单价 BIN 码 4Byte 精确到小数点后五位
     * [61-64] 第 1 个占位费单价 BIN 码 4Byte 精确到小数点后五位
     * [65-68] 第 1 个预约费单价 BIN 码 4Byte 精确到小数点后五位
     */
    @Data
    public static class PeriodVO {

        /**
         * 时段起始时间点 分钟
         */
        private Byte minute;

        /**
         * 时段起始时间点 小时
         */
        private Byte hour;

        /**
         * 时段标志 BIN 码 1Byte 1：尖时段；2：峰时段 3：平时段，4：谷时段
         */
        private Byte periodType;

        /**
         * 尖时段尖电价
         */
        @ByteType(len = 4, decimalNum = 5)
        private Float sharpPrice;

        /**
         * 峰时段电价
         */
        @ByteType(len = 4, decimalNum = 5)
        private Float peakPrice;

        /**
         * 平时段电价
         */
        @ByteType(len = 4, decimalNum = 5)
        private Float flatPrice;

        /**
         * 谷时段电价
         */
        @ByteType(len = 4, decimalNum = 5)
        private Float valleyPrice;

        /**
         * 服务费
         */
        @ByteType(len = 4, decimalNum = 5)
        private Float serviceFee;

        /**
         * 占位费
         */
        @ByteType(len = 4, decimalNum = 5)
        private Float spaceFee;

        /**
         * 预约费
         */
        @ByteType(len = 4, decimalNum = 5)
        private Float retainingFee;
    }

}

字节数组转对象

// 由于上层已经封装好了IEC104规约的应用规约控制信息（APCI）和数据单元标识符 通俗理解即头部信息已经封装好了。只需要对消息体的差异做单独解析即可。
// msgBytes 是从记录类型开始直到结束的所有字节数组
// 以下一行代码即可完成解析
CloudFeeModeVO cloudFeeModeVO = RecordDataUtils.cloudConvertToObj(msgBytes, CloudFeeModeVO.class);

四总结

作为一名优秀的码农，我们写代码前，一定要思考一下如何实现才是最好的。
也许有些实现方式会让你前期花不少功夫去磨针，但是等针磨好了，后续开发效率和代码质量都会非常高。

如果，你也熟悉充电桩规约，或者正在对接充电桩协议，都非常欢迎关注一下我，然后加我微信沟通交流。

二 通常的解析方式

三 优雅的解析或转字节数组做法

四 总结

二通常的解析方式

三优雅的解析或转字节数组做法

四总结