Vue implements student management function

<script>
 let app = new Vue({
  el:"#app",
  data:{
   currentPage:1, //Current page pageSize:10, //Number of records displayed per page total:0, //Total number of records;
   list:[], //Current page data //Binding student information student:{
    name:"",
    age:""
   }
  },
  methods:{
   pager:function(num){
    this.currentPage = num;
    this.getData();
   },
   getData:function () {
    axios.post("/StudentManager/showAllServlet?currentPage=" + this.currentPage + "&pageSize=" + this.pageSize).then((resp) => {
     this.list = resp.data.datas;
     this.total = resp.data.total;
    });
   },
   add:function () {
    if (this.student.id === undefined) {
     axios.post("/StudentManager/addStudentServlet", this.student).then((resp) =>{
      if (resp.data.flag){
       this.getData();
      }else {
       alert("Add failed!");
      }
     });
    }else {
     axios.post("/StudentManager/updateStudentServlet", this.student).then((resp)=>{
      if (resp.data.flag){
       this.getData();
      }else {
       alert("Modification failed!");
      }
     });
    }
   },
   deleteStudent:function (id) {
    axios.post("/StudentManager/deleteStudentServlet?id="+id).then((resp)=>{
     if (resp.data.flag){
      this.getData();
     }else {
      alert("Delete failed!");
     }
    });
   },
   findById:function (id) {
    axios.post("/StudentManager/findByIdStudentServlet?id=" + id).then((resp)=>{
     this.student = resp.data;
    });
   }
  },
  mounted:function () {
   this.getData();
  }
 });
</script>

// Servlet
 String currentPage = request.getParameter("currentPage");
 String pageSize = request.getParameter("pageSize");
 
 PageBean<Student> pageBean = showAllStudentService.showAllStudent(Integer.parseInt(currentPage), Integer.parseInt(pageSize));
 ObjectMapper objectMapper = new ObjectMapper();
 String json = objectMapper.writeValueAsString(pageBean);
 
 response.getWriter().write(json);
// Service
  @Test
    @Override
    public PageBean<Student> showAllStudent(int currentPage, int pageSize) {
        PageHelper.startPage(currentPage, pageSize);
        SqlSession sqlSession = SqlSessionUtils.getSqlSession(false);
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        List<Student> students = mapper.showStudent();

        PageInfo<Student> pageInfo = new PageInfo<>(students);
        long total = pageInfo.getTotal();
        int pages = pageInfo.getPages();
        PageBean<Student> pageBean = new PageBean<>(total, students, pages);
        sqlSession.close();
        return pageBean;
    }
//Dao
 /**
     * Home page shows all students* @return student list*/
    @Select("SELECT * FROM student")
    List<Student> showStudent();