FastJsonIssue.java

public class FastJsonIssue {
    public static class Record {
        @JSONField(format = "yyyy-MMM-dd")
        public Date date1 = new Date();

        @JSONField(format = "yyyyMMdd")
        public Date date2 = date1;

        @JSONField(format = "yyyy_MM_dd hh:mm")
        public DateTime dateTime = DateTime.now();
    }

    public static class JodaDateTimeSerializer implements ObjectSerializer {
        @Override
        public void write(JSONSerializer serializer, Object object, Object fieldName, Type fieldType, int features) throws IOException {
            SerializeWriter out = serializer.getWriter();
            if (object == null) {
                out.writeNull();
            } else {
                Class cls = object.getClass();
                if (cls == DateTime.class) {
                    out.writeString(object.toString());
                } else {
                    out.writeString(object.toString());
                }
            }
        }
    }

    public static void main(String[] args) {
        SerializeConfig.getGlobalInstance().put(DateTime.class, new JodaDateTimeSerializer());
        System.out.println(JSON.toJSONString(new Record()));
    }
}