解决FastJson中"$ref重复引用"的问题方法

public static void main(String[] args) {
 UserGroup userGroup = new UserGroup().setName("UserGroup");

 User user = new User("User");
 for (int i = 0; i < 3; i++) {
  userGroup.addUser(user);
 }
 Console.log(JSON.toJSONString(userGroup));
}


@Data
@AllArgsConstructor
static class User {
 private String name;
}

@Data
@Accessors(chain = true)
static class UserGroup {
 private String name;
 private List<User> users = Lists.newArrayList();

 public UserGroup addUser(User user) {
  this.getUsers().add(user);
  return this;
 }
}

{"$ref": "$"} // 引用根对象
{"$ref":"@"} // 引用自己
{"$ref":".."} // 引用父对象
{"$ref":"../.."} // 引用父对象的父对象
{"$ref":"$.members[0].reportTo"} // 基于路径的引用

public static void main(String[] args) {
 Order order = new Order().setName("Order");
 Item item = new Item().setName("Item");

 item.setOrder(order);
 order.setItem(item);

 Console.log(JSON.toJSONString(order));
 Console.log("----------------------------");
 Console.log(JSON.toJSONString(item));
}

@Data
@Accessors(chain = true)
static class Order {
 private String name;
 private Item item;
}

@Data
@Accessors(chain = true)
static class Item {
 private String name;
 private Order order;
}

JSON.toJSONString(obj, SerializerFeature.DisableCircularReferenceDetect)

public static void main(String[] args) {
 UserGroup userGroup = new UserGroup().setName("UserGroup");

 User user = new User("User");
 for (int i = 0; i < 3; i++) {
  User duplicateUser = new User();
  BeanUtil.copyProperties(user, duplicateUser);
  userGroup.addUser(duplicateUser);
 }
 Console.log(JSON.toJSONString(userGroup));
}