ElementUI组件Cascader级联选择器数据后台处理

Cascader级联选择器数据数据格式不知道的可以去官网看下；这里我就不表示什么了。

部门实体类：

 import lombok.Data;

 @Data
 public class Department {
     private Integer id;

     private Integer parentId;

     private String name;

     public Department(Integer id, Integer parentId, String name) {
         this.id = id;
         this.parentId = parentId;
         this.name = name;
     }

     public static TreeItem deptNode(Department dept) {
         TreeItem treeItem = new TreeItem();
         treeItem.setId(dept.getId());
         treeItem.setName(dept.getName());
         treeItem.setParentId(dept.getParentId());
         return treeItem;
     }
 }

用户实体类：

 import lombok.Data;

 @Data
 public class Employee {

     private Integer id;

     private String name;

     private Integer deptId;

     public Employee(Integer id, String name, Integer deptId) {
         this.id = id;
         this.name = name;
         this.deptId = deptId;
     }

     public static TreeItem empNode(Employee emp) {
         TreeItem treeItem = new TreeItem();
         treeItem.setId(emp.getId());
         treeItem.setName(emp.getName());
         treeItem.setParentId(emp.getDeptId());
         return treeItem;
     }
 }

返回数据实体类：

 import lombok.Data;

 import java.util.List;

 @Data
 public class TreeItem {
     private Integer id;

     private Integer parentId;

     private String name;

     private List<TreeItem> children;
 }

数据处理操作，这里是用java8新的特性写的。不懂的可以学习下，挺好用的

 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;

 public class App {
     public static void main(String[] args) {
         //创建部门
         List<Department> deptList = Arrays.asList(
                 new Department(1, 0, "星宇"),
                 new Department(2, 1, "金3"),
                 new Department(3, 2, "金3/1"),
                 new Department(4, 2, "金3/2"),
                 new Department(5, 1, "总1"),
                 new Department(6, 5, "总1/2")

         );
         //创建员工
         List<Employee> empList = Arrays.asList(
                 new Employee(1, "张三", 5),
                 new Employee(2, "李四", 6),
                 new Employee(3, "王五", 2),
                 new Employee(4, "赵六", 2),
                 new Employee(5, "田七", 3),
                 new Employee(6, "牛八", 4)
         );
         //转换成结点
         List<TreeItem> allDept = deptList.stream()
                 .map(Department::deptNode)
                 .collect(Collectors.toList());
         //按照上级部门分组
         Map<Integer, List<TreeItem>> deptMap = allDept.stream()
                 .collect(Collectors.groupingBy(TreeItem::getParentId));
         //给每个部门绑定子部门
         allDept.forEach(node ->
                 node.setChildren(deptMap.get(node.getId()))
         );

         List<TreeItem> treeItem = deptMap.get(0);

         Map<Integer, List<TreeItem>> empMap = empList.stream()
                 .filter(emp -> emp.getDeptId() != null)
                 .map(Employee::empNode)
                 .collect(Collectors.groupingBy(TreeItem::getParentId));
         //BFS辅助队列
         List<TreeItem> queue = new ArrayList<>();
         queue.addAll(treeItem);
         for (int i = 0; i < queue.size(); i++) {
             TreeItem node = queue.get(i);
             //遍历时先将子部门放入队列中
             if (node.getChildren() != null) {
                 queue.addAll(node.getChildren());
             } else {
                 node.setChildren(new ArrayList<>());
             }
             //再将部门成员放入子结点中
             List<TreeItem> children = empMap.get(node.getId());
             if (children != null) {
                 node.getChildren().addAll(children);
             }
         }

         treeItem.forEach(x -> System.out.println(x));

     }
 }

TreeItem(id=1, parentId=0, name=星宇, children=[TreeItem(id=2, parentId=1, name=金3, children=[TreeItem(id=3, parentId=2, name=金3/1, children=[TreeItem(id=5, parentId=3, name=田七, children=null)]), TreeItem(id=4, parentId=2, name=金3/2, children=[TreeItem(id=6, parentId=4, name=牛八, children=null)]), TreeItem(id=3, parentId=2, name=王五, children=null), TreeItem(id=4, parentId=2, name=赵六, children=null)]), TreeItem(id=5, parentId=1, name=总1, children=[TreeItem(id=6, parentId=5, name=总1/2, children=[TreeItem(id=2, parentId=6, name=李四, children=null)]), TreeItem(id=1, parentId=5, name=张三, children=null)])])

上面是我打印出来的数据，其实你们只要返回treeItem这个集合就可以了，这个数据结构符合Cascader级联选择器。