JDK1.8

public class RegionBeanTree implements Serializable{

//保证3个参数 其他随意

private static final long serialVersionUID = 1L;

private String code;

private String pid;

private String label;

}

public class TreeToolUtils {

private List rootList; //根节点对象存放到这里

private List bodyList; //其他节点存放到这里，可以包含根节点

public TreeToolUtils(List rootList, List bodyList) {

this.rootList = rootList;

this.bodyList = bodyList;

}

public List getTree(){ //调用的方法入口

if(bodyList != null && !bodyList.isEmpty()){

//声明一个map，用来过滤已操作过的数据

Map map = Maps.newHashMapWithExpectedSize(bodyList.size());

rootList.forEach(beanTree -> getChild(beanTree,map));

return rootList;

}

return null;

}

public void getChild(RegionBeanTree beanTree,Map map){

List childList = Lists.newArrayList();

bodyList.stream()

.filter(c -> !map.containsKey(c.getCode()))

.filter(c ->c.getPid().equals(beanTree.getCode()))

.forEach(c ->{

map.put(c.getCode(),c.getPid());

getChild(c,map);

childList.add(c);

});

beanTree.setChildren(childList);

}

public static void main(String[] args){

RegionBeanTree beanTree1 = new RegionBeanTree();

beanTree1.setCode("540000");

beanTree1.setLabel("西藏省");

beanTree1.setPid("100000"); //最高节点

RegionBeanTree beanTree2 = new RegionBeanTree();

beanTree2.setCode("540100");

beanTree2.setLabel("拉萨市");

beanTree2.setPid("540000");

RegionBeanTree beanTree3 = new RegionBeanTree();

beanTree3.setCode("540300");

beanTree3.setLabel("昌都市");

beanTree3.setPid("540000");

RegionBeanTree beanTree4 = new RegionBeanTree();

beanTree4.setCode("540121");

beanTree4.setLabel("林周县");

beanTree4.setPid("540100");

RegionBeanTree beanTree5 = new RegionBeanTree();

beanTree5.setCode("540121206");

beanTree5.setLabel("阿朗乡");

beanTree5.setPid("540121");

RegionBeanTree beanTree6 = new RegionBeanTree();

List rootList = new ArrayList<>();

rootList.add(beanTree1);

List bodyList = new ArrayList<>();

bodyList.add(beanTree1);

bodyList.add(beanTree2);

bodyList.add(beanTree3);

bodyList.add(beanTree4);

bodyList.add(beanTree5);

TreeToolUtils utils = new TreeToolUtils(rootList,bodyList);

List result = utils.getTree();

result.get(0);

}

}