fastjon案例

--json为json串
JSONObject obj = JSON.parseObject(json);
String x = obj.getString("cropId");
JSONArray arr = obj.getJSONArray("seals");
JSONObject usr = obj.getJSONObject("agent");
Map<String,Object> map = usr;
List<Map<String,Object>> list = (List) arr;

JSON.toJSONString(map);
SiteInfoBean siteInfoBean = JSON.parseObject(JSON.toJSONString(map), SiteInfoBean.class);

--对象序列化，null值属性被忽略，如何解决
JSONObject.toJSONString(Object object, SerializerFeature... features)
JSONObject.toJSONString(object,SerializerFeature.WriteMapNullValue);
SerializerFeature常用枚举介绍:
QuoteFieldNames———-输出key时是否使用双引号,默认为true
WriteMapNullValue——–是否输出值为null的字段,默认为false
WriteNullNumberAsZero—-数值字段如果为null,输出为0,而非null
WriteNullListAsEmpty—–List字段如果为null,输出为[],而非null
WriteNullStringAsEmpty—字符类型字段如果为null,输出为”“,而非null
WriteNullBooleanAsFalse–Boolean字段如果为null,输出为false,而非null