JAVA 转换 树结构数据

第一步：引入fastjson

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

第二步：用到了工具内的JSONPath

JSONPath使用教程

/**
 * 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);
    }
}