package test;import java.util.ArrayList;import java.util.HashMap;import java.util.LinkedList;import java.util.List;import java.util.Map;/** * IdPIdDatasToTree<BR> * <P>Author : td </P>   * <P>Date : 2016年9月30日下午4:54:59</P> * <P>Desc : 将上下级数据加工成为tree形数据结构</P> * @param response * @param request */public class IdPIdDatasToTree {    public static void main(String[] args) {        List < Map < String, Object >> list = new ArrayList < Map < String, Object >> ();        Map < String, Object > m = null;        for (int i = 1; i < 10; i++) {            m = new HashMap < String, Object > ();            m.put("id", i + "");            m.put("name", "我是节点" + i);            m.put("parentId", i - 1 + "");            list.add(m);        }        List < Map < String, Object >> treeMenuList = new LinkedList < Map < String, Object >> ();        treeMenuList = treeMenuList(list, treeMenuList, "0");        System.out.println("要加工的数据为：" + list.toString());        System.out.println("加工好的tree状结构为：" + treeMenuList.toString());    }    /**     *      * @param menuList 原始数据     * @param treeMenuList tree数据对象     * @param parentId  数据的父id     * @return     */    @SuppressWarnings("unchecked")    public static List < Map < String, Object >> treeMenuList(List < Map < String, Object >> list, List < Map < String, Object >> treeMenuList, String parentId) {        //没有根节点情况下        if ("0".equals(parentId)) {            treeMenuList = getChildNodeList("0", list);            for (Map < String, Object > treeMenu: treeMenuList) {                String id = (String) treeMenu.get("id");                treeMenu.put("childNode", getChildNodeList(id, list));                treeMenuList(list, treeMenuList, id);            }        } else {            for (Map < String, Object > treeMenu: treeMenuList) {                //判断是否有子元素，有的话递归子元素 继续判断                String id = (String) treeMenu.get("id");                if (treeMenu.containsKey("childNode")) {                    //获取子元素                    List < Map < String, Object >> childNodeList = (List < Map < String, Object >> ) treeMenu.get("childNode");                    if (childNodeList != null && childNodeList.size() > 0) {                        for (Map < String, Object > tMenu: childNodeList) {                            treeMenuList(list, childNodeList, tMenu.get("id").toString());                        }                    }                    //如果没有子元素，根据id查询儿子 将儿子赋值                } else {                    List < Map < String, Object >> chList = getChildNodeList(id, list);                    if (null != chList) {                        treeMenu.put("childNode", chList);                        treeMenuList(list, chList, id);                    }                }            }        }        return treeMenuList;    }    /**     *      * @param parentId 数据父id     * @param list  原始数据     * @return     */    public static List < Map < String, Object >> getChildNodeList(String parentId, List < Map < String, Object >> list) {        List < Map < String, Object >> childNodeList = new LinkedList < Map < String, Object >> ();        for (Map < String, Object > childNode: list) {            //从新new 对象 (如果不重新new对象，list 的值会随之变动，不知道咋回事？)            Map < String, Object > m = new HashMap < String, Object > ();            m.putAll(childNode);            String pId = (String) childNode.get("parentId");            if (pId.equals(parentId)) {                childNodeList.add(m);            }        }        if (childNodeList.size() == 0) return null;        return childNodeList;    }}