JAVA如何转换树结构数据代码实例

<dependency>
  <groupId>com.alibaba</groupId>
  <artifactId>fastjson</artifactId>
  <version>${fastjson.version}</version>
</dependency>

  /**
   * 树转换
   *
   * @param obj         需要转换的对象
   * @param parentCodeFieldName 父标识字段名
   * @param parentCode      父标识值
   * @param currentCodeFieldName 当前标识字段名
   * @param childrenFiledName  子树的字段名
   * @param c          需要转换的Class类型
   * @param <T>         泛型
   * @return 返回List<T>
   */
  public static <T> List<T> tree(Object obj, String parentCodeFieldName, String parentCode, String currentCodeFieldName, String childrenFiledName, Class<T> c) {
    long t1 = System.currentTimeMillis();
    String jsonStr = JSON.toJSONString(obj);
    log.debug("树转换开始 >>>>>>>>>>>>>>>> {}", JSON.toJSONString(obj));
    //获取第一层级的数据
    JSONArray jsonArray = (JSONArray) JSONPath.read(jsonStr, "$[" + parentCodeFieldName + "=" + parentCode + "]");
    if (CollectionUtils.isEmpty(jsonArray)) {
      //为空的话直接返回空集合
      return Lists.newArrayList();
    }
    for (int i = 0; i < jsonArray.size(); i++) {
      JSONObject jsonObject = jsonArray.getJSONObject(i);
      String code = jsonObject.getString(currentCodeFieldName);
      treeChildren(jsonStr, jsonObject, parentCodeFieldName, code, currentCodeFieldName, childrenFiledName);
    }
    List<T> list = JSONArray.parseArray(jsonArray.toString(), c);
    log.debug("树转换结束, 转换时间: {} ms . >>>>>>>>>>>>>>>> {}", (System.currentTimeMillis() - t1), JSON.toJSONString(list));
    return list;
  }

  private static void treeChildren(String jsonStr, JSONObject currentJsonObj, String parentCodeFieldName, String parentCode, String currentCodeFieldName, String childrenFiledName) {
    JSONArray jsonArray = (JSONArray) JSONPath.read(jsonStr, "$[" + parentCodeFieldName + "=" + parentCode + "]");
    if (CollectionUtils.isEmpty(jsonArray)) {
      return;
    }
    currentJsonObj.put(childrenFiledName, jsonArray);
    for (int i = 0; i < jsonArray.size(); i++) {
      JSONObject jsonObject = jsonArray.getJSONObject(i);
      String code = jsonObject.getString(currentCodeFieldName);
      treeChildren(jsonStr, jsonObject, parentCodeFieldName, code, currentCodeFieldName, childrenFiledName);
    }
  }