使用效果

初始化加载顶层节点，点击各层的>加载该节点的子节点，加载后>标识去除不再重复加载。

前端代码

vue ant-design组件

• tree-data，树节点，children方式或id、pid方式
• load-data，展开节点事件，响应该事件加载子节点

<a-tree-select v-model:value="sample" :tree-data="sampleTreeData" :load-data="onLoadSampleTreeData"         style="width: 100%" allowClear treeDataSimpleMode          :dropdown-style="{ maxHeight: '400px', overflow: 'auto' }"         placeholder="请选择测试计划/样品" >                            </a-tree-select> 

定义interface

• 异步加载通过id和pid匹配，因此没有children属性，替换为id何pid
• 添加level便于后端识别，如果后端为一个表内的数据且通过id和pid或parentid关联则不需要

export interface TreeDataItem {   id: string | number;   pId: string | number;   value: string;   title: string;   isLeaf?: boolean;   level: string; } 

加载（跟节点）数据

调用后端查询数据并赋值给treeData，treeData绑定控件的treeData属性。

async function loadSampleTreeRootData() {   // loading.value = true   let params = {"level":"0"};   sampleTreeNode(params).then(result => {        console.log(result)       sampleTreeData.value = sampleTreeData.value.concat(result);       }).finally(() => {        });   // loading.value = false   } loadSampleTreeRootData() 

加载（节点的子节点）数据

响应控件的load-data事件，查询要展开节点的子节点数据，并合并到treeData中，控件会根据id和pid显示层级关系。

const onLoadSampleTreeData = (treeNode: any) => {        return new Promise((resolve: (value?: unknown) => void) => {         // console.log("node:");         // console.log(treeNode.dataRef)         const { id,level,value } = treeNode.dataRef;          // console.log("id:"+id);         // console.log("level:"+level);         // console.log("value:"+value);          setTimeout(() => {              let nextLevel = "1";             if(level=="1")nextLevel="2";             let params = {"level":nextLevel, "id":id};              sampleTreeNode(params).then(result => {              //    console.log("result:");             //    console.log(result);                  sampleTreeData.value = sampleTreeData.value.concat(result);              }).finally(() => {              });            resolve();         }, 300);       });     }; 

后端代码

定义treeNodeVO

pId和isLeaf注解下，避免springMVC默认的序列化。
（默认序列化为pid/leaf）

@Data public class PlantSampleTreeNodeVO {     //key     private String id; //    private long id;      @JsonProperty("pId")     private String pId; //    private long pId;      //树节点显示的内容     private String title;      //默认根据此属性值进行筛选（其值在整个树范围内唯一）     private Object value;      //是否是叶子节点     @JsonProperty("isLeaf")     private boolean isLeaf;      //节点层级     private String level;  } 

controller提供数据

因为是异步加载，三个表的查询可在一个service中实现，或直接使用各自的treeNode的service。

@Override  public List<PlantSampleTreeNodeVO> getPlantSampleTreeNodeVO(String level, String id) {   List<PlantSampleTreeNodeVO> plantSampleTreeVONodeList = new ArrayList<>();   switch (level) {//顶级节点    case "0":     //查询所在班组,plant member     List<Plant> plantList = plantService.list();     for (Plant plant : plantList) {      //创建顶层树/节点      PlantSampleTreeNodeVO plantNode = new PlantSampleTreeNodeVO(); //     System.out.println(plant.getId()); //     System.out.println(Long.parseLong(plant.getId())); //     System.out.println(Long.valueOf(plant.getId()).longValue()); //     plantNode.setId(Long.parseLong(plant.getId()));      plantNode.setId(plant.getId());      plantNode.setPId("0");//and-design tree指定的值      plantNode.setValue(plant.getId());      plantNode.setTitle(plant.getPlantName());      plantNode.setLeaf(false);//需根据业务逻辑判断是否有子节点，省略处理      plantNode.setLevel("0");      plantSampleTreeVONodeList.add(plantNode);     }     break;    case "1":     //查询班组相关的样品组模板     QueryWrapper<SampleGroupTemplate> sampleGroupTemplateQueryWrapper = new QueryWrapper<>();     sampleGroupTemplateQueryWrapper.eq("plantid",id);     List<SampleGroupTemplate> sampleGroupTemplateList = sampleGroupTemplateService.list(sampleGroupTemplateQueryWrapper);     //循环各样品组模板显示其下的测试计划/样品     for(SampleGroupTemplate sampleGroupTemplate: sampleGroupTemplateList){      //添加到树上      PlantSampleTreeNodeVO sampleGroupNode = new PlantSampleTreeNodeVO(); //     sampleGroupNode.setId(Long.parseLong(sampleGroupTemplate.getId()));      sampleGroupNode.setId(sampleGroupTemplate.getId()); //     sampleGroupNode.setPId(Long.parseLong(id));      sampleGroupNode.setPId(id);      sampleGroupNode.setValue(sampleGroupTemplate.getId());      sampleGroupNode.setTitle(sampleGroupTemplate.getSampleGroupName());      sampleGroupNode.setLeaf(false);      sampleGroupNode.setLevel("1");      plantSampleTreeVONodeList.add(sampleGroupNode);     }     break;    case "2":     //查询样品组模板显示其下的测试计划/样品     QueryWrapper<SgtSample> sampleQueryWrapper = new QueryWrapper<>();     sampleQueryWrapper.eq("templateid",id);     List<SgtSample> sampleList = this.list(sampleQueryWrapper);     //循环各样品     for(SgtSample sample: sampleList) {      PlantSampleTreeNodeVO sampleNode = new PlantSampleTreeNodeVO(); //     sampleNode.setId(Long.parseLong(sample.getId()));      sampleNode.setId(sample.getId()); //     sampleNode.setPId(Long.parseLong(id));      sampleNode.setPId(id);      sampleNode.setValue(sample.getId());      sampleNode.setTitle(sample.getSampleName());      sampleNode.setLeaf(true);//叶子节点      sampleNode.setLevel("2");      plantSampleTreeVONodeList.add(sampleNode);     }     break;   }   return plantSampleTreeVONodeList;  }