JSONObject.toJSONString null值转成“”

秒速五厘米 2022-11-07 01:45 360阅读 0赞

1.  SerializerFeature.WriteMapNullValue 是否输出值为null的字段,默认为false  
    也就是说有null时会输出而不是忽略（默认策略是忽略，所以看不到为null的字段）
2.  WriteNullStringAsEmpty—字符类型 键如果为null,输出为”“,而非null  
    注意是*键为null的可以转换为“”*，而不是json.put("key",null)
3.  如果让输出的json中所有为null
    
    的字符串都变成空字符串，最简单的做法就是加一个值过滤器，这样就避免了有的字段为null，有的字段值为空字符的现象。
    
        private ValueFilter filter = new ValueFilter() {
        		@Override
        		public Object process(Object obj, String s, Object v) {
        			if(v==null)
        				return "";
        			return v;
        		}
        	};
        	@Test
        	void jsonTest()  {
        		String s="{\"bdcdyh\":\"140722001003\",\"bz\":null,\"ch\":\"25\",\"cqxz\":null,\"dytdmj\":\"0\",\"fflb\":null,\"fjsxh\":null,\"fttdmj\":\"31.415\",\"fwbm\":\"140722\",\"fwcb\":null,\"fwdh\":null,\"fwjg\":\"1\",\"fwjs\":null,\"fwlb\":\"1\",\"fwlx\":\"1\",\"fwxz\":\"0\",\"fwyt1\":\"11\",\"fwyt2\":null,\"fwyt3\":null,\"ghyt\":\"11\",\"gxsj\":null,\"gytdmj\":\"31.415\",\"hh\":\"1\",\"jcnf\":null,\"jgsj\":null,\"ljzh\":\"140722001003\",\"mycs\":null,\"qxdm\":\"140722\",\"scdxbfjzmj\":\"0\",\"scftjzmj\":\"0\",\"scftxs\":\"0\",\"scjzmj\":\"0\",\"scqtjzmj\":\"0\",\"sctnjzmj\":\"0\",\"sjcs\":\"25\",\"szc\":\"25\",\"tddj\":null,\"tdqlxz\":\"102\",\"tdsyjssj\":\"2088-04-09 00:00:00\",\"tdsyqmj\":\"31.415\",\"tdsyqssj\":\"2018-04-10 00:00:00\",\"tdyt\":\"071\",\"tdytmc\":\"城镇\",\"ybdcdyh\":null,\"ycdxbfjzmj\":\"0\",\"ycftjzmj\":\"31.41\",\"ycftxs\":\"0\",\"ycjzmj\":\"149.84\",\"ycqtjzmj\":\"0\",\"yctnjzmj\":\"118.42\",\"yxtbm\":\"H\",\"yxtbsm\":\"1400010",\"yxtfwlxmc\":\"住宅\",\"yxtfwxzmc\":\"市场化商品\",\"yxtfwytmc1\":\"成套住宅\",\"yxtfwytmc2\":null,\"yxtfwytmc3\":null,\"yxtghytmc\":null,\"zcs\":\"25\",\"zddm\":\"140722001003GB00998\",\"zdmj\":\"31.415\",\"zdshiyqbsm\":null,\"zfbsm\":null,\"zl\":\"小区2号楼1单元12501室\",\"zrzh\":\"111111111\",\"zts\":null}";
        		Map json=JSONObject.parseObject(s,Map.class);
        
        		System.out.println(JSONObject.toJSONString(json));
        //filter结合  WriteMapNullValue实现
        		System.out.println(JSONObject.toJSONString(json,filter, SerializerFeature.WriteMapNullValue, SerializerFeature.WriteNullStringAsEmpty));
        	
        
        	}