1. /**
    2.  * 树列表Domain类的接口
    3.  */
    4. public interface TreeItemInterface {
    6.     Integer getId();
    8.     Integer getParentId();
    10.     List getChildren();
    12.     void setChildren(List children);
    14. }
    1. /**
    2.  * 树列表帮助类
    3.  *
    4.  * @param <T>
    5.  */
    6. public class TreeListHelper<T extends TreeItemInterface> {
    8.     /**
    9.      * 获取带本节点的树列表
    10.      *
    11.      * @param sourceList
    12.      * @param parentId
    13.      * @return
    14.      */
    15.     public List<T> getTreeListByParentId(List<? extends TreeItemInterface> sourceList, int parentId) {
    16.         List<T> targetList = new ArrayList<>();
    18.         //先把自己获取
    19.         T rootTreeItem = null;
    21.         for (TreeItemInterface ti : sourceList) {
    22.             if (ti.getId() == parentId) {
    23.                 rootTreeItem = (T) ti;
    24.             }
    25.         }
    27.         if (rootTreeItem != null) {
    28.             //再把子项获取
    29.             rootTreeItem.setChildren(getChildrenTreeListByParentId(sourceList, parentId));
    30.             targetList.add(rootTreeItem);
    31.         }
    33.         return targetList;
    34.     }
    36.     /**
    37.      * 获取不带本节点的树列表
    38.      *
    39.      * @param sourceList
    40.      * @param parentId
    41.      * @return
    42.      */
    43.     public List<T> getChildrenTreeListByParentId(List<? extends TreeItemInterface> sourceList, int parentId) {
    44.         List<TreeItemInterface> targetList = new ArrayList<>();
    46.         for (TreeItemInterface item : sourceList) {
    47.             if (item.getParentId() == parentId) {
    49.                 boolean hasChildren = false;
    50.                 for (TreeItemInterface tempItem : sourceList) {
    51.                     if (tempItem.getParentId() == item.getId()) {
    52.                         hasChildren = true;
    53.                         break;
    54.                     }
    55.                 }
    57.                 if (hasChildren) {
    58.                     item.setChildren(getChildrenTreeListByParentId(sourceList, item.getId()));
    59.                 }
    61.                 targetList.add(item);
    62.             }
    63.         }
    65.         //转换为目标类型
    66.         List<T> tList = new ArrayList<>();
    67.         for (TreeItemInterface ti : targetList) {
    68.             tList.add((T) ti);
    69.         }
    71.         return tList;
    72.     }
    74. }