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本篇內容主要講解“springboot構造樹形結構數據并查詢的方法是什么”，感興趣的朋友不妨來看看。本文介紹的方法操作簡單快捷，實用性強。下面就讓小編來帶大家學習“springboot構造樹形結構數據并查詢的方法是什么”吧!
因為項目需要，頁面上需要樹形結構的數據進行展示（類似下圖這樣），因此需要后端返回相應格式的數據。
我這里用的是springboot+mybatis-plus+mysql，示例的接口是查詢一級權限以及二級權限、三級權限整個權限樹…
下面是導入的maven依賴
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <!--數據庫連接--> <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增強工具--> <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>
下面是實體類Permission
@Data
public class Permission implements Serializable {
@TableId
private String permissionId;
@NotNull(message = "權限名稱不能為空")
private String permissionName;
/**
* 權限標識
*/
@NotNull(message = "權限標識不能為空")
private String permissionCode;
/**
* 父菜單ID，如果是-1就表示是一級權限菜單。
*/
@NotBlank(message = "父菜單ID不能為空")
private String parentId;
/**
* 前端URL訪問接口路徑
*/
private String path;
/**
* 排序值
*/
private Integer sort;
/**
* 創建時間
*/
private LocalDateTime createTime;
/**
* 更新時間
*/
private LocalDateTime updateTime;
/**
* 0--正常 1--刪除
*/
private String delFlag;
public Permission() {
this.permissionId = IdUtil.simpleUUID();
}樹形結點類
@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);
}
}樹形結點詳細信息類
@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() {
}
}構建樹形結點工具類（關鍵），在這里我用@UtilityClass注解就表示這個類中的方法都是靜態方法：
@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;
}
/**
* 通過permission創建樹形節點
*
* @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);
}
}響應消息主體類
/**
* 響應信息主體
*
* @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;
}
}數據查詢接口mapper類
@Mapper
public interface PermissionMapper extends BaseMapper<Permission>{
}數據邏輯處理業務接口
public interface PermissionService extends IService<Permission> {
/**
* 構建權限樹
*
* @param lazy
* @param parentId
* @return
*/
List<PermissionTree> treePermission(boolean lazy, String parentId);
}數據邏輯處理業務接口實現類
@Service
public class PermissionServiceImpl extends ServiceImpl<PermissionMapper, Permission> implements PermissionService {
/**
* 構建權限樹：1、不是懶加載情況，查詢全部
* 2、是懶加載，根據parentId查詢
*
* @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
);
}
}查詢權限樹請求接口類
@RestController
@RequestMapping("/permission")
public class PermissionController {
@Autowire
private PermissionService permissionService;
/**
* 查詢權限列表，并以樹狀結構顯示
*
* @param lazy 懶加載: false時, parentId這個參數失效, 加載所有的權限; true時, 根據parentId加載
* @param parentId
* @return
*/
@RequestMapping(value = "/getTree", method = RequestMethod.GET)
public R getTree(boolean lazy, String parentId) {
return R.ok(permissionService.treePermission(lazy, parentId));
}
}表中測試數據如下（注意它的parent_id）
測試一：不是懶加載，查詢整個權限樹。 結果如下。
{
"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
}
]
}測試二：是懶加載，根據parent_id查詢當前分支。 結果如下。
{
"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
}
]
}到此，相信大家對“springboot構造樹形結構數據并查詢的方法是什么”有了更深的了解，不妨來實際操作一番吧！這里是億速云網站，更多相關內容可以進入相關頻道進行查詢，關注我們，繼續學習！
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