1.新建一个TreeUtil的类

package com.zdnst.common.infra.utils;import java.util.*;/*** 把一个list集合,里面的bean含有 parentId 转为树形式**/
public class TreeUtil {/*** 判断两个父ID是否相同* @param p1* @param p2* @return*/private boolean isEqualsParentId(Object p1,Object p2){if(p1!=null && p1!=null){return p1.equals(p2);}else if(p1==null && p2 == null) {return true;}else if(p1==null && p2 != null) {if("".equals(p2.toString())){return true;}else{return false;}}else if(p1!=null && p2 == null) {if("".equals(p1.toString())){return true;}else{return false;}}else{return false;}}/*** 根据父节点的ID获取所有子节点，该方法顶级节点必须为空* @param list 分类表* @param parentId 传入的父节点ID* @return String*/public List<TreeObject> getChildTreeObjects(List<TreeObject> list,Object parentId) {List<TreeObject> returnList = new ArrayList<TreeObject>();if(list!=null&&list.size()>0) {for (Iterator<TreeObject> iterator = list.iterator(); iterator.hasNext(); ) {TreeObject t = (TreeObject) iterator.next();// 一、根据传入的某个父节点ID,遍历该父节点的所有子节点if (isEqualsParentId(t.getParentId(), parentId)) {recursionFn(list, t);returnList.add(t);}}if(returnList==null||returnList.size()==0){//如果返回出空结果，则说明非树，直接返回原来结果for (Iterator<TreeObject> iterator = list.iterator(); iterator.hasNext(); ) {TreeObject t = (TreeObject) iterator.next();returnList.add(t);}}}return returnList;}/*** 根据父节点的ID获取所有子节点，该方法顶级节点可以不为空,非树直接返回* @param list 分类表* @return String*/public List<TreeObject> getChildTreeObjects(List<TreeObject> list) {if(list!=null&&list.size()>0) {List<TreeObject> topList=new ArrayList<>();List<TreeObject> subList=new ArrayList<>();Map<String,String> idMap=new HashMap<>();for (Iterator<TreeObject> iterator = list.iterator(); iterator.hasNext(); ) {//归并所有list的id集合TreeObject t = (TreeObject) iterator.next();if(t.getId()!=null){idMap.put(t.getId().toString(), t.getId().toString());}}for (Iterator<TreeObject> iterator = list.iterator(); iterator.hasNext(); ) {//获取最顶级的listTreeObject t = (TreeObject) iterator.next();if(t.getParentId()==null||StringUtils.isEmpty(t.getParentId().toString())){topList.add(t);}else{String id=idMap.get(t.getParentId().toString());if(StringUtils.isEmpty(id)){topList.add(t);}else{subList.add(t);}}}if(topList!=null&&topList.size()>0&&subList!=null&&subList.size()>0){List<TreeObject> resultList=new ArrayList<>();for (TreeObject t:topList) {//将儿子级别的list归并到顶级中List<TreeObject> subOneList=new ArrayList<>();for (TreeObject sub:subList) {// 一、根据传入的某个父节点ID,遍历该父节点的所有子节点if (isEqualsParentId(sub.getParentId(), t.getId())) {recursionFn(subList, sub);subOneList.add(sub);}}if(subOneList!=null&&subOneList.size()>0) {t.setChildren(subOneList);}resultList.add(t);}return resultList;}else{return list;}}return list;}/*** 递归列表* @author lanyuan* Email: mmm333zzz520@163.com* @date 2013-12-4 下午7:27:30* @param list* @param t*/private void  recursionFn(List<TreeObject> list, TreeObject t) {List<TreeObject> childList = getChildList(list, t);// 得到子节点列表t.setChildren(childList);for (TreeObject tChild : childList) {if (hasChild(list, tChild)) {// 判断是否有子节点//returnList.add(TreeObject);Iterator<TreeObject> it = childList.iterator();while (it.hasNext()) {TreeObject n = (TreeObject) it.next();recursionFn(list, n);}}}}// 得到子节点列表private List<TreeObject> getChildList(List<TreeObject> list, TreeObject t) {List<TreeObject> tlist = new ArrayList<TreeObject>();Iterator<TreeObject> it = list.iterator();while (it.hasNext()) {TreeObject n = (TreeObject) it.next();if (isEqualsParentId(n.getParentId(),t.getId())) {tlist.add(n);}}return tlist;} List<TreeObject> returnList = new ArrayList<TreeObject>();/*** 根据父节点的ID获取所有子节点* @param list 分类表* @param parentId 传入的父节点ID* @param prefix 子节点前缀*/public List<TreeObject> getChildTreeObjects(List<TreeObject> list, Object parentId,String prefix){if(list == null) return null;for (Iterator<TreeObject> iterator = list.iterator(); iterator.hasNext();) {TreeObject node = (TreeObject) iterator.next();// 一、根据传入的某个父节点ID,遍历该父节点的所有子节点if (isEqualsParentId(node.getParentId(),parentId)) {recursionFn(list, node,prefix);}// 二、遍历所有的父节点下的所有子节点/*if (node.getParentId()==0) {recursionFn(list, node);}*/}return returnList;}private void recursionFn(List<TreeObject> list, TreeObject node,String p) {List<TreeObject> childList = getChildList(list, node);// 得到子节点列表if (hasChild(list, node)) {// 判断是否有子节点returnList.add(node);Iterator<TreeObject> it = childList.iterator();while (it.hasNext()) {TreeObject n = (TreeObject) it.next();n.setName(p+n.getName());recursionFn(list, n,p+p);}} else {returnList.add(node);}}// 判断是否有子节点private boolean hasChild(List<TreeObject> list, TreeObject t) {return getChildList(list, t).size() > 0 ? true : false;}// 本地模拟数据测试public void main(String[] args) {/*long start = System.currentTimeMillis();List<TreeObject> TreeObjectList = new ArrayList<TreeObject>();TreeObjectUtil mt = new TreeObjectUtil();List<TreeObject> ns=mt.getChildTreeObjects(TreeObjectList,0);for (TreeObject m : ns) {System.out.println(m.getName());System.out.println(m.getChildren());}long end = System.currentTimeMillis();System.out.println("用时:" + (end - start) + "ms");*/}}

2.新建类TreeObject

package com.zdnst.common.infra.utils;import java.util.List;/*** 这个是列表树形式显示的接口*/
public interface TreeObject {public Object getId();public void setId(Object id);public Object getParentId();public void setParentId(Object parentId);public String getName();public void setName(String name);public List getChildren();public void setChildren(List children);}

3.具体列表实体PubCompTypeDto实现TreeObject ：

package com.zdnst.core.sys.application.dto;import com.zdnst.common.infra.dto.BaseDto;
import com.zdnst.common.infra.utils.TreeObject;import java.util.List;public class PubCompTypeDto extends BaseDto  implements TreeObject {private static final long serialVersionUID = 5726287409752473211L;private String comTypeItemCode;//公司类型CODE,由类型key+具体code组合private String comTypeItemName;//类型项名称private String comTypeItemDesc;//类型项描述private String parentCode;//父idprivate Long comTypeItemStatus;//1启用0停用/*** 类型KEY：* 环节：FN_LEAVE_CODE* 物品：FN_GOODS_CODE* 场地：FN_FIELD_CODE* 车辆：FN_CAR_CODE*/private String comTypeKey;private String companyId;//公司idprivate Long seqNo; private List children;//构造树使用public String getComTypeItemCode() {return comTypeItemCode;}public void setComTypeItemCode(String comTypeItemCode) {this.comTypeItemCode = comTypeItemCode == null ? null : comTypeItemCode.trim();}public String getComTypeItemName() {return comTypeItemName;}public void setComTypeItemName(String comTypeItemName) {this.comTypeItemName = comTypeItemName == null ? null : comTypeItemName.trim();}public String getComTypeItemDesc() {return comTypeItemDesc;}public void setComTypeItemDesc(String comTypeItemDesc) {this.comTypeItemDesc = comTypeItemDesc == null ? null : comTypeItemDesc.trim();}public String getParentCode() {return parentCode;}public void setParentCode(String parentCode) {this.parentCode = parentCode == null ? null : parentCode.trim();}public Long getComTypeItemStatus() {return comTypeItemStatus;}public void setComTypeItemStatus(Long comTypeItemStatus) {this.comTypeItemStatus = comTypeItemStatus;}public String getComTypeKey() {return comTypeKey;}public void setComTypeKey(String comTypeKey) {this.comTypeKey = comTypeKey == null ? null : comTypeKey.trim();}public String getCompanyId() {return companyId;}public void setCompanyId(String companyId) {this.companyId = companyId == null ? null : companyId.trim();}public Long getSeqNo() {return seqNo;}public void setSeqNo(Long seqNo) {this.seqNo = seqNo;}@Override
    public Object getId() {return getComTypeItemCode();}@Overridepublic void setId(Object id) {setComTypeItemCode((String)id);}@Overridepublic Object getParentId() {return getParentCode();}@Overridepublic void setParentId(Object parentId) {setParentCode((String)parentId);}@Overridepublic String getName() {return getComTypeItemName();}@Overridepublic void setName(String name) {setComTypeItemName(name);}@Overridepublic List getChildren() {return this.children;}@Overridepublic void setChildren(List children) {this.children = children;}
}

4.在使用中如下调用：

TreeUtil treeUtil = new TreeUtil();
List<TreeObject> treeList = treeUtil.getChildTreeObjects(pubCompTypeDtoList);
return JsonView.dataToJson(treeList, response);