<dependency>
<groupId>javax.validation</groupId>
<artifactId>validation-api</artifactId>
<version>2.0.1.Final</version>
</dependency>
package com.ytkj.rose.util; import org.springframework.util.StringUtils; import javax.validation.constraints.NotNull; import java.lang.reflect.Field; import java.util.ArrayList; import java.util.Collection; import java.util.HashSet; import java.util.Set; public class TreeUtils { /** * 集合转树结构 * * @param collection 目标集合 * @param clazz 集合元素类型 * @return 转换后的树形结构 */ public static <T> Collection<T> toTree(@NotNull Collection<T> collection, @NotNull Class<T> clazz) { return toTree(collection, null, null, null, clazz); } /** * 集合转树结构 * * @param collection 目标集合 * @param id 节点编号字段名称 * @param parent 父节点编号字段名称 * @param children 子节点集合属性名称 * @param clazz 集合元素类型 * @return 转换后的树形结构 */ public static <T> Collection<T> toTree(@NotNull Collection<T> collection, String id, String parent, String children, @NotNull Class<T> clazz) { try { if (collection == null || collection.isEmpty()) return null;// 如果目标集合为空,直接返回一个空树 if (StringUtils.isEmpty(id)) id = "id"; // 如果被依赖字段名称为空则默认为id if (StringUtils.isEmpty(parent)) parent = "parent"; // 如果依赖字段为空则默认为parent if (StringUtils.isEmpty(children)) children = "children"; // 如果子节点集合属性名称为空则默认为children // 初始化根节点集合, 支持 Set 和 List Collection<T> roots; if (collection.getClass().isAssignableFrom(Set.class)) { roots = new HashSet<>(); } else { roots = new ArrayList<>(); } // 获取 id 字段, 从当前对象或其父类 Field idField; try { idField = clazz.getDeclaredField(id); } catch (NoSuchFieldException e1) { idField = clazz.getSuperclass().getDeclaredField(id); } // 获取 parentId 字段, 从当前对象或其父类 Field parentField; try { parentField = clazz.getDeclaredField(parent); } catch (NoSuchFieldException e1) { parentField = clazz.getSuperclass().getDeclaredField(parent); } // 获取 children 字段, 从当前对象或其父类 Field childrenField; try { childrenField = clazz.getDeclaredField(children); } catch (NoSuchFieldException e1) { childrenField = clazz.getSuperclass().getDeclaredField(children); } // 设置为可访问 idField.setAccessible(true); parentField.setAccessible(true); childrenField.setAccessible(true); // 找出所有的根节点 for (T c : collection) { Object parentId = parentField.get(c); if (isRootNode(parentId)) { roots.add(c); } } // 从目标集合移除所有根节点 collection.removeAll(roots); // 遍历根节点, 依次添加子节点 for (T root : roots) { addChild(root, collection, idField, parentField, childrenField); } // 关闭可访问 idField.setAccessible(false); parentField.setAccessible(false); childrenField.setAccessible(false); return roots; } catch (Exception e) { e.printStackTrace(); throw new RuntimeException(e); } } /** * 为目标节点添加孩子节点 * * @param node 目标节点 * @param collection 目标集合 * @param idField ID 字段 * @param parentField 父节点字段 * @param childrenField 字节点字段 */ private static <T> void addChild(@NotNull T node, @NotNull Collection<T> collection, @NotNull Field idField, @NotNull Field parentField, @NotNull Field childrenField) throws IllegalAccessException { Object id = idField.get(node); Collection<T> children = (Collection<T>) childrenField.get(node); // 如果子节点的集合为 null, 初始化孩子集合 if (children == null) { if (collection.getClass().isAssignableFrom(Set.class)) { children = new HashSet<>(); } else children = new ArrayList<>(); } for (T t : collection) { Object o = parentField.get(t); if (id.equals(o)) { // 将当前节点添加到目标节点的孩子节点 children.add(t); // 重设目标节点的孩子节点集合,这里必须重设,因为如果目标节点的孩子节点是null的话,这样是没有地址的,就会造成数据丢失,所以必须重设,如果目标节点所在类的孩子节点初始化为一个空集合,而不是null,则可以不需要这一步,因为java一切皆指针 childrenField.set(node, children); // 递归添加孩子节点 addChild(t, collection, idField, parentField, childrenField); } } } /** * 判断是否是根节点, 判断方式为: 父节点编号为空或为 0, 则认为是根节点. 此处的判断应根据自己的业务数据而定. * @param parentId 父节点编号 * @return 是否是根节点 */ private static boolean isRootNode(Object parentId) { boolean flag = false; if (parentId == null) { flag = true; } else if (parentId instanceof String && (StringUtils.isEmpty(parentId) || parentId.equals("0"))) { flag = true; } else if (parentId instanceof Integer && Integer.valueOf(0).equals(parentId)) { flag = true; } return flag; } }
测试：
List<TMenu> list = tMenuMapper.selectAll(); Collection<TMenu> tMenus = TreeUtils.toTree(list, "id", "pid", "children", TMenu.class); logger.debug("菜单={}",tMenus);
结果
[TMenu { id = 1, pid = 0, name = '控制面板', icon = 'glyphicon glyphicon-dashboard', url = 'main.html', children = [] }, TMenu { id = 2, pid = 0, name = '权限管理', icon = 'glyphicon glyphicon glyphicon-tasks', url = 'null', children = [TMenu { id = 3, pid = 2, name = '用户维护', icon = 'glyphicon glyphicon-user', url = 'admin/index.html', children = [] }, TMenu { id = 4, pid = 2, name = '角色维护', icon = 'glyphicon glyphicon-king', url = 'role/index.html', children = [] }, TMenu { id = 5, pid = 2, name = '权限维护', icon = 'glyphicon glyphicon-lock', url = 'permission/index.html', children = [] }, TMenu { id = 6, pid = 2, name = '菜单维护', icon = 'glyphicon glyphicon-th-list', url = 'menu/index.html', children = [] }] }, TMenu { id = 7, pid = 0, name = '业务审核', icon = 'glyphicon glyphicon-ok', url = 'null', children = [TMenu { id = 8, pid = 7, name = '实名认证审核', icon = 'glyphicon glyphicon-check', url = 'auth_cert/index.html', children = [] }, TMenu { id = 9, pid = 7, name = '广告审核', icon = 'glyphicon glyphicon-check', url = 'auth_adv/index.html', children = [] }, TMenu { id = 10, pid = 7, name = '项目审核', icon = 'glyphicon glyphicon-check', url = 'auth_project/index.html', children = [] }] }, TMenu { id = 11, pid = 0, name = '业务管理', icon = 'glyphicon glyphicon-th-large', url = 'null', children = [TMenu { id = 12, pid = 11, name = '资质维护', icon = 'glyphicon glyphicon-picture', url = 'cert/index.html', children = [] }, TMenu { id = 13, pid = 11, name = '分类管理', icon = 'glyphicon glyphicon-equalizer', url = 'certtype/index.html', children = [] }, TMenu { id = 14, pid = 11, name = '流程管理', icon = 'glyphicon glyphicon-random', url = 'process/index.html', children = [] }, TMenu { id = 15, pid = 11, name = '广告管理', icon = 'glyphicon glyphicon-hdd', url = 'advert/index.html', children = [] }, TMenu { id = 16, pid = 11, name = '消息模板', icon = 'glyphicon glyphicon-comment', url = 'message/index.html', children = [] }, TMenu { id = 17, pid = 11, name = '项目分类', icon = 'glyphicon glyphicon-list', url = 'projectType/index.html', children = [] }, TMenu { id = 18, pid = 11, name = '项目标签', icon = 'glyphicon glyphicon-tags', url = 'tag/index.html', children = [] }] }, TMenu { id = 19, pid = 0, name = '参数管理', icon = 'glyphicon glyphicon-list-alt', url = 'param/index.html', children = [] }]
