Java实现返回的数据为树形结构

最新推荐文章于 2024-07-20 14:42:31 发布

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本文介绍了一种将基于实体类的数据转换为树形结构的方法。通过递归遍历实体类列表，根据实体的父ID和等级属性，构建出带有层级关系的树形结构数据。适用于系统菜单、文件目录等场景。

1.实体类为：

id:主键

name:名字

parent_id:父id

grade:等级

根据list中的实体类数据返回树形结构，代码如下：

public class TSystemTreeUtil {

     public static Map<String,Object> mapArray = new LinkedHashMap<String, Object>();
     public static List<TSystem> menuCommon;

     public static List<Object> menuList(List<TSystem> menu){
      List<Object> list = new ArrayList<>();
       menuCommon = menu;
       for (TSystem x : menu) {
         Map<String,Object> mapArr = new LinkedHashMap<String, Object>();
         mapArr.put("id", x.getId());
         mapArr.put("sys_name",x.getSysName());
         mapArr.put("category", x.getCategory());
         mapArr.put("project_name", x.getProjectName()==null?null:x.getProjectName());
         mapArr.put("standard", x.getStandard()==null?null:x.getStandard());
         mapArr.put("contents", x.getContents()==null?null:x.getContents());
         mapArr.put("fraction", x.getFraction()==null?null:x.getFraction());
         if("1".equals(x.getGrade())){
                mapArr.put("remarks",x.getCategory());
            }else if("2".equals(x.getGrade())){
                mapArr.put("remarks",x.getProjectName());
            }else if("3".equals(x.getGrade())){
                mapArr.put("remarks",x.getStandard());
            }
         mapArr.put("child", menuChild(x.getId()));  //去子集查找遍历

         list.add(mapArr);
       }
       return list;
     }

     public static List<?> menuChild(Long id){ //子集查找遍历
       List<Object> lists = new ArrayList<Object>();
       for(TSystem a:menuCommon){
         Map<String,Object> childArray = new LinkedHashMap<String, Object>();
         if (null == a.getParentId()){
           continue;
        }
         if(a.getParentId().equals(id)){
           childArray.put("id", a.getId());
           childArray.put("sys_name",a.getSysName());
           childArray.put("category", a.getCategory());
           childArray.put("project_name", a.getProjectName()==null ? null :a.getProjectName());
           childArray.put("standard", a.getStandard()==null ? null :a.getStandard());
           childArray.put("contents", a.getContents()==null?null:a.getContents());
           childArray.put("fraction", a.getFraction()==null?null:a.getFraction());
              if("1".equals(a.getGrade())){
                  childArray.put("remarks",a.getCategory());
              }else if("2".equals(a.getGrade())){
                  childArray.put("remarks",a.getProjectName());
              }else if("3".equals(a.getGrade())){
                  childArray.put("remarks",a.getStandard());
              }
           childArray.put("child", menuChild(a.getId()));
           lists.add(childArray);
         }else {
          continue;
        }
       }
       return lists;
     }

   }