递归的使用-- 国民经济行业类别集合递归树

controller

private static DCCommUtil commUtil; 
1 
@RequestMapping("/getALLIndustryTotree")
    public Result getALLIndustryTotree() {
        Result result = new Result();
        //1、查询所有国民经济行业类别
        List<industry> industryList=codeService.getALLIndustry();
        List<industry> returnIndustryList = new ArrayList<industry>();
        //2、遍历国民经济行业类别
        for (industry industry : industryList) {
            if (industry.getPid().equals("0")) {
                //3、调用递归组装树
                industry = commUtil.buildTree(industryList, industry);
                returnIndustryList.add(industry);
            }
        }
        try {
            result = result.buileSuccess();
            result.setData(returnIndustryList);
        } catch (Exception e) {
            result = result.buileFailure();
            result.setData(e.getMessage());
        }
        return result;
    }

DCCommUtil.java

public class DCCommUtil {
    /**
     * 国民经济行业类别集合递归树
     * @param list
     * @param industry
     * @return
     */
    public static industry buildTree(List<industry> list, industry industry){
        List<industry> children = new ArrayList<industry>();
        for (industry item : list) {
            if (item.getPid().equals(industry.getId())) {
                children.add(buildTree(list, item));
            }
        }
        industry.setChildren(children);
        return industry;
    }

industry.java

public class industry {
    private String id;
    private String pid;
    private String singlehyname;
    private List<industry> children=new ArrayList();

mapper.xml         CASE  WHEN

<!-- 查询所有国民经济行业类别 -->
    <select id="getALLIndustry" resultType="com.mapuni.datacenter.entity.industry">
        select 
            id,
            (CASE pid WHEN '' THEN '0' WHEN NULL THEN '0' ELSE pid END) as pid, 
            singlehyname 
        from t_cod_industry
    </select>