Jackson转换实体 double 保留两位小数

public class CustomDoubleSerialize extends JsonSerializer<Double> {

private DecimalFormat df = new DecimalFormat("##.00");

@Override
public void serialize(Double value, JsonGenerator gen, SerializerProvider serializers)
throws IOException, JsonProcessingException {
if(value != null) {
gen.writeString(df.format(value));
}
}
}

/**
* 应还金额：项目系统：amt - principalReturn
*/
@JsonSerialize(using = CustomDoubleSerialize.class)
private Double needReturn;
public Double getNeedReturn() {
if(amt == null || principalReturn == null) {
if(amt != null) {
return amt;
}
if(principalReturn != null) {
return 0 - principalReturn;
}
return null;
}
return amt - principalReturn;
}