递归组装树

/**
	 * 装成树
	 * @param regions
	 * @return
	 */
	//获取树的集合
	public List toEasyUITree(List regions) {
		// TODO Auto-generated method stub
		//实体类集合转化为dtos
		List regionsdto=toDTOs(regions);
		//将dtos装入EasyUITreeDTOs
		List regionList=this.toEasyUITreeDTO(regionsdto);
		List roots = new ArrayList();
		//找到树的根节点
		for (EasyUITreeDTO regionTree : regionList) {
			String str=regionTree.getPid();
				if(StringUtils.isEmpty(str)){
					//获取父节点下的子节点
					regionTree.setChildren(getChildrenNode(regionTree.getId(),regionList));
					regionTree.setState("open");
					regionTree.setIconCls("icon-coalmine");
					roots.add(regionTree);
				}
			}
		return roots;
	}
	/**
	 * 获取子节点
	 * @param id
	 * @param regionList
	 * @return
	 */
	private List getChildrenNode(String id, List regionList) {
		// TODO Auto-generated method stub
		List newTreeList=new ArrayList();
		for (EasyUITreeDTO regionTreeDTO : regionList) {
			if( StringUtils.isEmpty(regionTreeDTO.getPid())){
				continue;
			}
			//这是一个子节点
			if(id.equals(regionTreeDTO.getPid())){
				//递归获取子节点下的子节点
				regionTreeDTO.setChildren(getChildrenNode(regionTreeDTO.getId(),regionList));
				newTreeList.add(regionTreeDTO);
			}
		}
		return newTreeList;
	}
	
	/**
	 * dtos转化为EasyUITreeDTOs
	 * @param regionsdto
	 * @return
	 */
	private List toEasyUITreeDTO(List regionsdto) {
		// TODO Auto-generated method stub
		List list=new ArrayList();
		for (RegionDTO regionDTO : regionsdto) {
			EasyUITreeDTO result = new EasyUITreeDTO();
			result.setId(regionDTO.getId());
			result.setText(regionDTO.getName());
			result.setPid(regionDTO.getUpRegionId());
			list.add(result);
		}
		return list;
	}