项目里有几个字段 是BigDecimal 类型，前台表单校验，限制最多有两位小数，数据库是最多6位小数，所以查询出的数据可能是整数，可能有1位小数，可能有2位。

需要统一返回都是2位小数

代码

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.ser.ContextualSerializer;
import org.springframework.boot.jackson.JsonComponent;
import java.io.IOException;
import java.math.BigDecimal;
import java.text.DecimalFormat;
import java.util.Objects;

@JsonComponent
public class BigDecimalSerializer extends JsonSerializer<BigDecimal> implements ContextualSerializer {
    private String format = "#####0.00";

    @Override
    public void serialize(BigDecimal bigDecimal, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
        jsonGenerator.writeString(new DecimalFormat(format).format(bigDecimal));
    }

    @Override
    public JsonSerializer<?> createContextual(SerializerProvider serializerProvider, BeanProperty beanProperty) throws JsonMappingException {
        if(beanProperty !=null ){
            if(Objects.equals(beanProperty.getType().getRawClass(),BigDecimal.class)){
                BigDecimalFormat bigDecimalFormat = beanProperty.getAnnotation((BigDecimalFormat.class));
                if(bigDecimalFormat == null){
                    bigDecimalFormat = beanProperty.getContextAnnotation(BigDecimalFormat.class);
                }
                BigDecimalSerializer bigDecimalSerializer = new BigDecimalSerializer();
                if(bigDecimalFormat != null){
                    bigDecimalSerializer.format = bigDecimalFormat.value();
                }
                return bigDecimalSerializer;
            }
            return serializerProvider.findValueSerializer(beanProperty.getType(),beanProperty);
        }
        return serializerProvider.findNullValueSerializer(beanProperty);
    }
}

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import org.springframework.boot.jackson.JsonComponent;
import java.io.IOException;
import java.math.BigDecimal;

@JsonComponent
public class BigDecimalDeSerializer extends JsonDeserializer<BigDecimal> {
    @Override
    public BigDecimal deserialize(JsonParser jsonParser, 
                                  DeserializationContext deserializationContext) throws IOException, JsonProcessingException {

        return new BigDecimal(jsonParser.getText().replaceAll(",",""));
    }
}

import com.fasterxml.jackson.annotation.JacksonAnnotationsInside;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
@JacksonAnnotationsInside
@JsonSerialize(using = BigDecimalSerializer.class)
@JsonDeserialize(using = BigDecimalDeSerializer.class)
public @interface BigDecimalFormat {
    String value() default "#####0.00";
}

使用，在需要的字段上

@BigDecimalFormat
private BigDecimal price;

其实还有另外的方法，但是是全局生效，

参考链接

https://www.jianshu.com/p/db07543ffe0a