实体对象转JSONObject

@Data
public class Entity {
    private String age;
    private String name;
    private String class;
}

Entity entity = new Entity("20","灰太狼");
String jsonString = JSON.toJSONString(entity);
JSONObject jsonObject = JSONObject.parseObject(jsonString);
System.out.println(jsonObject);

-- 字段为NULL的则不会展示
{"age":"20","name":"灰太狼"}