因为项目需要，页面上需要树形结构的数据进行展示（类似下图这样），因此需要后端返回相应格式的数据。
不说废话，直接开干！！！
我这里用的是 springboot+mybatis-plus+mysql ，示例的接口是查询一级权限以及二级权限、三级权限整个权限树…
下面是导入的maven依赖
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< dependency > < groupId >org.springframework.boot</ groupId > < artifactId >spring-boot-starter-web</ artifactId > </ dependency > <!--数据库连接--> < dependency > < groupId >com.alibaba</ groupId > < artifactId >druid-spring-boot-starter</ artifactId > < version >1.1.21</ version > </ dependency >
< dependency > < groupId >mysql</ groupId > < artifactId >mysql-connector-java</ artifactId > </ dependency > <!--mybatis增强工具--> < dependency > < groupId >com.baomidou</ groupId > < artifactId >mybatis-plus-boot-starter</ artifactId > < version >3.4.0</ version > </ dependency > < dependency > < groupId >org.projectlombok</ groupId > < artifactId >lombok</ artifactId > < optional >true</ optional > </ dependency > < dependency > < groupId >cn.hutool</ groupId > < artifactId >hutool-all</ artifactId > < version >5.0.6</ version > </ dependency > |
下面是实体类Permission
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@Data public class Permission implements Serializable { @TableId private String permissionId; @NotNull (message = "权限名称不能为空" ) private String permissionName; /** * 权限标识 */ @NotNull (message = "权限标识不能为空" ) private String permissionCode; /** * 父菜单ID，如果是-1就表示是一级权限菜单。 */ @NotBlank (message = "父菜单ID不能为空" ) private String parentId;
/** * 前端URL访问接口路径 */ private String path;
/** * 排序值 */ private Integer sort; /** * 创建时间 */
private LocalDateTime createTime;
/** * 更新时间 */
private LocalDateTime updateTime;
/** * 0--正常 1--删除 */ private String delFlag;
public Permission() { this .permissionId = IdUtil.simpleUUID(); } |
树形结点类
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@Data public class TreeNode { protected String id; protected String parentId; protected List<TreeNode> children = new ArrayList<TreeNode>(); protected boolean hasChildren;
public void addTreeNode(TreeNode node){ children.add(node); } } |
树形结点详细信息类
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@Data @EqualsAndHashCode (callSuper = true ) public class PermissionTree extends TreeNode implements Serializable { private String permissionName; private String permissionCode; private String path; private Integer sort; private String label; private boolean hasChildren; public PermissionTree() { } } |
构建树形结点工具类（关键），在这里我用 @UtilityClass 注解就表示这个类中的方法都是静态方法：
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@UtilityClass public class TreeUtil {
public <T extends TreeNode> List<T> build(List<T> treeNodes, String root) { List<T> trees = new ArrayList<>(); for (T treeNode : treeNodes) {
if (root.equals(treeNode.getParentId())) { trees.add(treeNode); }
for (T node : treeNodes) { if (node.getParentId().equals(treeNode.getId())) { treeNode.addTreeNode(node); treeNode.setHasChildren( true );
} } } return trees; }
/** * 通过permission创建树形节点 * * @param permissionList * @param root * @return */ public List<PermissionTree> buildTree(List<Permission> permissionList, String root) { System.out.println(Arrays.toString(permissionList.toArray())); List<PermissionTree> treeNodeList = new ArrayList<>(); PermissionTree treeNode = null ; for (Permission permission : permissionList) { treeNode = new PermissionTree(); treeNode.setId(permission.getPermissionId()); treeNode.setPermissionName(permission.getPermissionName()); treeNode.setPath(permission.getPath()); treeNode.setSort(permission.getSort()); treeNode.setParentId(permission.getParentId()); treeNode.setLabel(permission.getPermissionName()); treeNode.setHasChildren( false ); treeNodeList.add(treeNode); } return TreeUtil.build(treeNodeList, root); } } |
响应消息主体类
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/** * 响应信息主体 * * @param <T> */ @ToString @NoArgsConstructor @AllArgsConstructor @Accessors (chain = true ) public class R<T> implements Serializable {
private static final long serialVersionUID = 1L;
private int code;
private String msg;
private T data;
public int getCode() { return code; }
public void setCode( int code) { this .code = code; }
public String getMsg() { return msg; }
public void setMsg(String msg) { this .msg = msg; }
public T getData() { return data; }
public void setData(T data) { this .data = data; }
public static <T> R<T> ok() { return restResult( null , CommonConstants.SUCCESS, CommonConstants.MSG_SUCCESS); }
public static <T> R<T> ok(T data) { return restResult(data, CommonConstants.SUCCESS, CommonConstants.MSG_SUCCESS); }
public static <T> R<T> ok(T data, String msg) { return restResult(data, CommonConstants.SUCCESS, msg); }
public static <T> R<T> failed() { return restResult( null , CommonConstants.FAIL, null ); }
public static <T> R<T> failed(String msg) { return restResult( null , CommonConstants.FAIL, msg); }
public static <T> R<T> failed(T data) { return restResult(data, CommonConstants.FAIL, null ); }
public static <T> R<T> failed(T data, String msg) { return restResult(data, CommonConstants.FAIL, msg); }
private static <T> R<T> restResult(T data, int code, String msg) { R<T> apiResult = new R<>(); apiResult.setCode(code); apiResult.setData(data); apiResult.setMsg(msg); return apiResult; } } |
数据查询接口mapper类
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@Mapper public interface PermissionMapper extends BaseMapper<Permission>{
} |
数据逻辑处理业务接口
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public interface PermissionService extends IService<Permission> {
/** * 构建权限树 * * @param lazy * @param parentId * @return */ List<PermissionTree> treePermission( boolean lazy, String parentId); } |
数据逻辑处理业务接口实现类
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@Service public class PermissionServiceImpl extends ServiceImpl<PermissionMapper, Permission> implements PermissionService { /** * 构建权限树：1、不是懒加载情况，查询全部 * 2、是懒加载，根据parentId查询 * * @param lazy * @param parentId * @return */
@Override public List<PermissionTree> treePermission( boolean lazy, String parentId) {
if (!lazy) { return TreeUtil.buildTree( baseMapper.selectList(Wrappers.<Permission>lambdaQuery().orderByAsc(Permission::getSort)), CommonConstants.PERMISSION_ROOT_ID); } String parent = parentId == null ? CommonConstants.PERMISSION_ROOT_ID : parentId; return TreeUtil.buildTree( baseMapper.selectList(Wrappers.<Permission>lambdaQuery().eq(Permission::getParentId, parent).orderByAsc(Permission::getSort)), parent ); } } |
查询权限树请求接口类
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@RestController @RequestMapping ( "/permission" ) public class PermissionController { @Autowire private PermissionService permissionService;
/** * 查询权限列表，并以树状结构显示 * * @param lazy 懒加载: false时, parentId这个参数失效, 加载所有的权限; true时, 根据parentId加载 * @param parentId * @return */ @RequestMapping (value = "/getTree" , method = RequestMethod.GET) public R getTree( boolean lazy, String parentId) { return R.ok(permissionService.treePermission(lazy, parentId)); } } |
表中测试数据如下（ 注意它的parent_id ）
测试一：不是懒加载，查询整个权限树。 结果如下。
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{ "code" : 0, "msg" : "SUCCESS" , "data" : [ { "id" : "1" , "parentId" : "-1" , "children" : [ { "id" : "2" , "parentId" : "1" , "children" : [ { "id" : "3" , "parentId" : "2" , "children" : [], "hasChildren" : false , "permissionName" : "update" , "permissionCode" : null , "path" : null , "sort" : 3, "label" : "update" , "owned" : false }, { "id" : "4" , "parentId" : "2" , "children" : [], "hasChildren" : false , "permissionName" : "insert_role" , "permissionCode" : null , "path" : null , "sort" : 4, "label" : "insert_role" , "owned" : false } ], "hasChildren" : true , "permissionName" : "delete" , "permissionCode" : null , "path" : null , "sort" : 2, "label" : "delete" , "owned" : false } ], "hasChildren" : true , "permissionName" : "add" , "permissionCode" : null , "path" : null , "sort" : 1, "label" : "add" , "owned" : false }, { "id" : "5" , "parentId" : "-1" , "children" : [], "hasChildren" : false , "permissionName" : "role:saveRole" , "permissionCode" : null , "path" : "/role/saveRole" , "sort" : 5, "label" : "role:saveRole" , "owned" : false } ] } |
测试二：是懒加载，根据parent_id查询当前分支。 结果如下。
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{ "code" : 0, "msg" : "SUCCESS" , "data" : [ { "id" : "3" , "parentId" : "2" , "children" : [], "hasChildren" : false , "permissionName" : "update" , "permissionCode" : null , "path" : null , "sort" : 3, "label" : "update" , "owned" : false }, { "id" : "4" , "parentId" : "2" , "children" : [], "hasChildren" : false , "permissionName" : "insert_role" , "permissionCode" : null , "path" : null , "sort" : 4, "label" : "insert_role" , "owned" : false } ] } |
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原文链接：https://blog.csdn.net/to10086/article/details/109730685
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