java中有时候须要对返回前端的数据做对立的数据格式化,如小数类型的字段须要格式化成保留两位小数的四舍五入格局; 这里应用两个注解: 一个标注类,一个标注字段,在返回前应用工具类办法调用一次,实现此指标.
1. 类上标注的注解@RoundMark
package com.niewj.common.annotation;import java.lang.annotation.*;/** * 数学字段须要格式化的类标记注解 * * @author niewj * @date 2023/3/8 16:03 */@Target({ElementType.TYPE})@Retention(RetentionPolicy.RUNTIME)@Documentedpublic @interface RoundMark {}2. 字段上标注的注解@Round
package com.niewj.common.annotation;import java.lang.annotation.*;/** * 实体字段格式化:float/double/decimal字段四舍五入保留2位小数(默认) * * @author niewj * @date 2023/3/8 16:03 */@Target({ElementType.FIELD})@Retention(RetentionPolicy.RUNTIME)@Documentedpublic @interface Round { int value() default 2;}3. 注解的应用
package com.niewj.business.model;import com.niewj.common.annotation.Round;import com.niewj.common.annotation.RoundMark;import lombok.Data;import java.math.BigDecimal;/** * 明细数据 * * @author niewj * @date 2023-02-12 */@Data@RoundMarkpublic class DataReturnToFront { /** * 商品skuid */ private Long skuId; /** * 总商品量 */ private Long count; /** * 商品均匀曝光量 */ @Round private Double avgExp; /** * 商品均匀曝光量-环比昨日 */ @Round private Double avgExpDodRatio; /** * 商品均匀曝光量-(新增) */ @Round private Double avgExpIncrement; /** * 商品[均匀曝光量]-环比昨日-新增 */ @Round private Double avgExpIncrementDodRatio; /** * 商品[均匀成交额] */ @Round private Double avgSaleAmt; /** * 商品[均匀成交额]-环比(昨日) */ @Round private Double avgSaleAmtDodRatio; /** * 商品[均匀成交额]-新增 */ @Round private Float avgSaleAmtIncrement; /** * 管控[均匀成交额]-环比(昨日)-新增 */ @Round private BigDecimal avgSaleAmtIncrementDodRatio;}4.注解的处理过程,工具类:
package com.niewj.common.util;import com.niewj.common.annotation.Round;import com.niewj.common.annotation.RoundMark;import lombok.extern.slf4j.Slf4j;import org.springframework.util.CollectionUtils;import java.lang.reflect.Field;import java.math.BigDecimal;import java.math.RoundingMode;import java.util.Arrays;import java.util.List;/** * 注解工具类:用于对实体对象通过类和字段上标记注解来解决对象 */@Slf4jpublic class AnnotationUtil { /** * 遍历格式化列表List内元素对象的数字字段 * * @param targetList 待处理数据汇合 * @param <T> */ public static <T> void roundListItemFields(List<T> targetList) { if (CollectionUtils.isEmpty(targetList)) { log.info("targetList为空,不须要解决"); return; } targetList.stream().forEach(e -> { roundDecimalValues(e); }); } /** * 对小数数字格局的数据四舍五入:对类上标注了@RoundMark/字段上标注了@Round的数据进行四舍五入 * * @param target 待处理实体对象 * @param <T> */ public static <T> void roundDecimalValues(T target) { Class<? extends Object> targetClass = target.getClass(); boolean hasRoundingNumberAnno = targetClass.isAnnotationPresent(RoundMark.class); if (hasRoundingNumberAnno) { //为属性解决字段值 roundDecimalField(targetClass, target); } } /** * 对指标类中的每个字段来匹配field注解,如果匹配则进行四舍五入 * * @param targetClass 标注了Round注解的类 * @param target 类的实例对象-即须要解决的字段所在对象 * @param <T> */ private static <T> void roundDecimalField(Class<? extends Object> targetClass, T target) { Field[] fields = targetClass.getDeclaredFields(); Arrays.stream(fields).forEach(field -> { boolean hasRoundingNumberAnno = field.isAnnotationPresent(Round.class); if (hasRoundingNumberAnno) { //获取注解的值 int scale = field.getAnnotation(Round.class).value(); Object originFieldVal; Object roundedFieldVal; try { field.setAccessible(true); originFieldVal = field.get(target); if (originFieldVal instanceof Float) { BigDecimal value = new BigDecimal(String.valueOf(originFieldVal)).setScale(scale, RoundingMode.HALF_UP); roundedFieldVal = value.floatValue(); } else if (originFieldVal instanceof Double) { BigDecimal value = new BigDecimal(String.valueOf(originFieldVal)).setScale(scale, RoundingMode.HALF_UP); roundedFieldVal = value.doubleValue(); } else if (originFieldVal instanceof BigDecimal) { roundedFieldVal = new BigDecimal(String.valueOf(originFieldVal)).setScale(scale, RoundingMode.HALF_UP); } else { roundedFieldVal = originFieldVal; } field.set(target, roundedFieldVal); } catch (IllegalAccessException e) { e.printStackTrace(); } } }); }}5.应用形式:controller端
@GetMapping("/test") @ResponseBody @RecCostTime public List<DataReturnToFront> test() { log.info("======================"); DataReturnToFront detail = new DataReturnToFront(); detail.setSkuId(233230L); detail.setCount(0L); detail.setAvgExp(2220.1234566D); detail.setAvgExpDodRatio(2220.1254566D); detail.setAvgExpIncrement(-2220.1254566D); detail.setAvgExpIncrementDodRatio(-2220.1264566D); detail.setAvgSaleAmt(2220.1234566D); detail.setAvgSaleAmtDodRatio(2220.1254566D); detail.setAvgSaleAmtIncrement(2220.1254566F); detail.setAvgSaleAmtIncrementDodRatio(BigDecimal.valueOf(0.1234566D)); DataReturnToFront detail2 = new DataReturnToFront(); detail2.setSkuId(5230L); detail2.setCount(2330L); detail2.setAvgExp(20.135634566D); detail2.setAvgExpDodRatio(22.55554566D); detail2.setAvgExpIncrement(-2220.5555D); detail2.setAvgExpIncrementDodRatio(-2220.5555D); detail2.setAvgSaleAmt(2220.5555D); detail2.setAvgSaleAmtDodRatio(2220.5555D); detail2.setAvgSaleAmtIncrement(2220.5555F); detail2.setAvgSaleAmtIncrementDodRatio(BigDecimal.valueOf(0.5555D)); List list = new ArrayList(); list.add(detail); list.add(detail2); // 四舍五入格式化-批量解决 AnnotationUtil.roundListItemFields(list); // 单个解决 AnnotationUtil.roundDecimalValues(detail); return list; }- roundDecimalValues是对单个对象的标注了@Round字段(前提是类上有@RoundMark标记)进行四舍五入批改字段值.
- roundListItemFields是对list遍历了一下.