SpringBoot 构建树形菜单 （Java Stream流 返回树形菜单 ）

原理

        1.创建带有关系型的实体类 Aircraft（id、pid、content、List<Aircraft> )

        2.通过两表（或多表之前的id、pid建立关联）

        3.用Stream过滤包装

效果 （前端用的vue的<el-tree>标签接的）

        

需求

        我的需求是三张表建立关联 如 t1 t2 t3,

        t1的id和t2的pid关联，t2的id和t3的pid关联。

一、创建实体

@Data
public class Aircraft {
    /**
     * id
     */
    private Long id;
    /**
     * 父id
     */
    private Long pid;
    /**
     * 名称
     */
    private String name;
    /**
     * 子节点集合
     */
    private List<Aircraft> children = new ArrayList<Aircraft>();

    public Aircraft(Long id, Long pid, String aircraftType) {
        this.id = id;
        this.pid = pid;
        this.name = aircraftType;
    }
}

二、Controller

    /**
     * 初开页面 menu全部展示
     */
    @GetMapping("/queryMenuTypeApi")
    public AjaxResult queryMenuTypeApi(){
        return success(aircraftService.queryMenuType());
    }

三、Service

    List<TreeSelect> queryMenuType();

四、Impl

    @Override
    public List<TreeSelect> queryMenuType() {
        //所有机型 表t1
        List<ConditionVo> knowledgeIdList = aircraftMapper.queryModel();
        List<Long> knowledgeIds = knowledgeIdList.stream().map( ConditionVo::getId ).collect(Collectors.toList());

        //机型对应的编号 表t2
        List<ConditionVo> aircraftNoList = aircraftMapper.queryModelNumber(knowledgeIds);
        List<Long> ids = aircraftNoList.stream().map(ConditionVo::getId).collect(Collectors.toList());

        //编号对应的工况树 表t3
        List<ConditionVo> conditionVos = aircraftMapper.queryTreeCondition(ids);
        List<Long> conIds = conditionVos.stream().map(ConditionVo::getId).collect(Collectors.toList());

        //工况树对应的详情表
//        List<ConditionVo> conditionVoss = aircraftMapper.queryTreeConditionDetails(conIds);

        //封装工况树
        //1.封装父类
        List<Aircraft> aircrafts = new ArrayList<>();
        aircrafts.add(new Aircraft(1L, 0L, "工况"));
//        aircrafts.add(new Aircraft(2L, null, "载荷"));
//        aircrafts.add(new Aircraft(3L, null, "AF"));
        //2.封装机型
        List<Aircraft> knowledgeAircraftVos = knowledgeIdList.stream()
                .map(knowledge -> new Aircraft(knowledge.getId(), 1L, knowledge.getAircraftType()))
                .collect(Collectors.toList());
        //3.封装编号
        List<Aircraft> aircraftNoListVos = aircraftNoList.stream()
                .map(aircraftNo -> new Aircraft(aircraftNo.getId(), aircraftNo.getKnowledgeId(), aircraftNo.getAircraftNo()))
                .collect(Collectors.toList());
        //4.文件名称
        List<Aircraft> conditionTree = conditionVos.stream()
                .map(Tree -> new Aircraft(Tree.getId(), Tree.getCatalogId(), Tree.getFileNameTime()))
                .collect(Collectors.toList());

        //------start

        //找出父节点
        List<Aircraft> parentList = aircrafts.stream()
                .filter(e -> e.getPid() == 0
                        || "".equals(e.getPid()))
                .collect(Collectors.toList());

        //通过倒叙组装，比正序方便
        //3-4
        List<Aircraft> aircrafts1 = get34(aircraftNoListVos, conditionTree);

        //2-3-4
        List<Aircraft> aircrafts2 = get234(knowledgeAircraftVos, aircrafts1);

        //1-2-3-4
        List<Aircraft> aircrafts3 = get1234(aircrafts, aircrafts2);

        //------end

        List<TreeSelect> result = aircrafts3.stream().map(TreeSelect::new).collect(Collectors.toList());

        return result;
    }

五、使用Stream，把子节点放入父节点下

    //1234
    private List<Aircraft> get1234(List<Aircraft> aircrafts,List<Aircraft> aircrafts2) {
        for (Aircraft exportOrganization : aircrafts) {
            List<Aircraft> subList = aircrafts2.stream().filter(o -> o.getPid()
                    .equals(exportOrganization.getId())).collect(Collectors.toList());
            exportOrganization.setChildren(subList);
        }
        return aircrafts;
    }

    //234
    private List<Aircraft> get234(List<Aircraft> knowledgeAircraftVos,List<Aircraft> aircrafts1) {
        for (Aircraft exportOrganization : knowledgeAircraftVos) {
            List<Aircraft> subList = aircrafts1.stream().filter(o -> o.getPid()
                    .equals(exportOrganization.getId())).collect(Collectors.toList());
            exportOrganization.setChildren(subList);
        }
        return knowledgeAircraftVos;
    }

    //34
    private List<Aircraft> get34(List<Aircraft> aircraftNoListVos,List<Aircraft> conditionTree) {
        for (Aircraft exportOrganization : aircraftNoListVos) {
            List<Aircraft> subList = conditionTree.stream().filter(o -> o.getPid()
                    .equals(exportOrganization.getId())).collect(Collectors.toList());
            exportOrganization.setChildren(subList);
        }
        return aircraftNoListVos;
    }

六、返回格式

@Data
public class TreeSelect implements Serializable
{
    private static final long serialVersionUID = 1L;

    /** 节点ID */
    private Long id;

    /** 节点名称 */
    private String label;

    /** 子节点 */
    @JsonInclude(JsonInclude.Include.NON_EMPTY)
    private List<TreeSelect> children;

    public TreeSelect(SysDept dept)
    {
        this.id = dept.getDeptId();
        this.label = dept.getDeptName();
        this.children = dept.getChildren().stream().map(TreeSelect::new).collect(Collectors.toList());
    }

    public TreeSelect(SysMenu menu)
    {
        this.id = menu.getMenuId();
        this.label = menu.getMenuName();
        this.children = menu.getChildren().stream().map(TreeSelect::new).collect(Collectors.toList());
    }

    public TreeSelect(Aircraft aircraft) {
        this.id = aircraft.getId();
        this.label = aircraft.getName();
        this.children = aircraft.getChildren().stream().map(TreeSelect::new).collect(Collectors.toList());

    }
}