使用@JsonSerialize注解处理单位换算以及数据默认值-Toy模板网

这篇具有很好参考价值的文章主要介绍了使用@JsonSerialize注解处理单位换算以及数据默认值。希望对大家有所帮助。如果存在错误或未考虑完全的地方，请大家不吝赐教，您也可以点击"举报违法"按钮提交疑问。

一、需求

使用@JsonSerialize，来解决单位换算，以及数据为空时返回“**”默认值问题。例如有时候我们需要将金额，以万元的形式返回，需要千分位等等。

注意：如果使用fastjson进行序列化，则本注解不会生效。此注解是jackson包下的。

二、pom依赖

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.12.3</version>
        </dependency>

三、通用序列化类定义

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;

import java.io.IOException;
import java.math.BigDecimal;
import java.text.DecimalFormat;

/**
 * @Author:
 * @Description 保留一位小数，且以千分位展示数据 例如：3,000.8
 * @Date: 下午4:44 2024/01/15
 */
@Slf4j
public class BigDecimalBaseSerializer extends JsonSerializer<Object> {

    private String format = "#,##0.0";

    private BigDecimal unit = BigDecimal.ONE;

    private DecimalFormat df = new DecimalFormat(format);

    private Integer scaleSize = 1;

    public static final String LINE_STR = "--";

    public BigDecimalBaseSerializer() {
    }

    public BigDecimalBaseSerializer(String format, BigDecimal unit, Integer scaleSize) {
        if (format != null) {
            this.format = format;
            this.df = new DecimalFormat(this.format);
        }
        if (unit != null) {
            this.unit = unit;
        }
        if (scaleSize != null) {
            this.scaleSize = scaleSize;
        }
    }

    @Override
    public void serialize(Object object, JsonGenerator gen, SerializerProvider serializer) throws IOException {
        BigDecimal val = toBigDecimal(object);
        if (val != null) {
            String str = bigDecimalToStr(val);
            gen.writeString(str);
        } else {
            gen.writeString(LINE_STR);
        }
    }

    public String bigDecimalToStr(BigDecimal val) {
        return toString(val, df, this.unit, this.scaleSize);
    }

    public String toString(BigDecimal val, DecimalFormat df, BigDecimal unit, Integer scaleSize) {
        if (BigDecimal.ZERO.equals(val)) {
            return df.format(val);
        } else if (unit != null) {
            val = val.divide(unit, 10, BigDecimal.ROUND_HALF_UP);
            val = val.setScale(scaleSize, BigDecimal.ROUND_HALF_UP);
            return df.format(val);
        }
        return LINE_STR;
    }

    public BigDecimal toBigDecimal(Object object) {
        BigDecimal res = null;
        if (object != null) {
            if (object instanceof BigDecimal) {
                res = ((BigDecimal) object);
            } else if (object instanceof String) {
                String str = (String) object;
                if (StringUtils.isNotBlank(str)) {
                    res = new BigDecimal(str);
                }
            } else if (object instanceof Integer) {
                Integer integer = (Integer) object;
                res = new BigDecimal(integer);
            } else if (object instanceof Double) {
                Double doubleVal = (Double) object;
                res = BigDecimal.valueOf(doubleVal);
            } else if (object instanceof Long) {
                Long longVal = (Long) object;
                res = new BigDecimal(longVal);
            } else {
                log.warn("BigDecimal转换异常{}", object.getClass().getTypeName());
            }
        }
        return res;
    }
}

四、以万为单位返回，保留一位小数

import java.math.BigDecimal;

/**
 * @Author:
 * @Description 以万为单位返回，保留一位小数
 * @Date: 下午4:58 2024/01/15
 */
public class TenThousandSerialize extends BigDecimalBaseSerializer {

    private static BigDecimal divisor = new BigDecimal(10000);

    public TenThousandSerialize() {
        super(null, divisor, null);
    }
}

五、以万为单位返回，取整数

/**
 * @Author:
 * @Description 以万为单位返回，取整数
 * @Date: 下午4:58 2024/01/15
 */
public class TenThousandIntegerSerializer extends BigDecimalBaseSerializer {

    private static Integer scaleSize = 0;

    private static BigDecimal divisor = new BigDecimal(10000);

    private static String pattern = "#,##0";

    public TenThousandIntegerSerializer() {
        super(pattern, divisor, scaleSize);
    }
}

六、构建实体类

import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import lombok.Data;

import java.math.BigDecimal;

/**
 * @Author: 
 * @Description
 * @Date: 下午2:15 2024/01/15
 */
@Data
public class EntityData {

    private String strNum;
    @JsonSerialize(using = TenThousandIntegerSerializer.class, nullsUsing = FieldNullSerializer.class)
    private BigDecimal bdNum;
    @JsonSerialize(using = BigDecimalBaseSerializer.class, nullsUsing = FieldNullSerializer.class)
    private BigDecimal bdNum1;

    @JsonSerialize(nullsUsing = FieldNullSerializer.class)
    private BigDecimal bdNum2;

}

七、测试

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.math.BigDecimal;

/**
 * @Author: 
 * @Description
 * @Date: 下午2:37 2024/1/15
 */
@RestController
@RequestMapping("/test")
public class TestController {

    @GetMapping("/111")
    public Object test1() {

        EntityData data = new EntityData();
        data.setStrNum(null);
        data.setBdNum(BigDecimal.valueOf(1101010.23));
        data.setBdNum1(BigDecimal.valueOf(1101010.23));
        return data;

    }

}