對象序列化不打印value值爲null的屬性問題

背景：

　　開發時遇到問題，看日誌的入參的busiData中沒有intRate這個屬性，後面轉成map時，有個判斷

if（map.containsKey("intRate")）｛
   BigDecimal amt = new BigDecimal(datas.get("intRate")); 
｝

一直報空指針異常，很鬱悶這個參數是怎麼添加進去的，並且值是null

 

測試代碼以下：

@Test
    public void test() {
        String json = "{\"busiData\":{\"intRate1\":null,\"intRate2\":\"\",\"overdueFlag\":\"N\",\"firstDue\":\"51.594\",\"loanPeriod\":\"12\"},\"loanAmt\":6000.00,\"loanDays\":30,\"productCode\":\"360JINXIAO\",\"refundMethod\":\"03\"}";
        CouponExchangeInput couponExchangeInput = JSONObject.parseObject(json, CouponExchangeInput.class);
        System.out.println(couponExchangeInput);
        logger.info("couponExchangeInput：{}", couponExchangeInput);

        System.out.println("---------");

        Map<Object, Object> map = new HashMap<>();
        map.put("intRate1",null); map.put("intRate2","");
        map.put("intRate3","aaa");
        System.out.println(map);
        logger.info("map：{}", map);
    }

結果：

{"busiData":{"overdueFlag":"N","firstDue":"51.594","loanPeriod":"12","intRate2":""},"loanAmt":6000.00,"loanDays":30,"productCode":"360JINXIAO","refundMethod":"03"}
INFO  [main] [TestCoupon:301] - couponExchangeInput：{"busiData":{"overdueFlag":"N","firstDue":"51.594","loanPeriod":"12","intRate2":""},"loanAmt":6000.00,"loanDays":30,"productCode":"360JINXIAO","refundMethod":"03"}
---------
{intRate3=aaa, intRate1=null, intRate2=}
INFO  [main] [TestCoupon:308] - map：{intRate3=aaa, intRate1=null, intRate2=}

 

結論：

　　對象的屬性值爲null，那麼日誌中不會打印該屬性；屬性值爲空字符串，日誌中會打印該屬性

　　map中，不論value值爲null仍是爲空字符串，日誌中都會打印全部的鍵值對；