通过ajax从jsp页面传输数据到web层，并从web层返回数据给jsp页面

jsp中ajax代码：
 1            $.ajax({
               var id = $("#studentid").val();//获取标签中的学生id
               url:'${pageContext.request.contextPath}/student/stu_delStudent.action?studentid='+id,
               data:'',
               type:'POST',
               dataType:'json',
               async:false,
               success:function(data){
                   alert(data.message);
               }

           }); 

action中的代码：
1 public class StudentAction extends ActionSupport{
     private Student student;
     public Student getStudent() {
         return student;
     }
     public void setStudent(Student student) {
         this.student = student;
     }

     @Resource
     private StudentService studentService;

     public String delStudent() throws Exception{
         //接收请求数据
         int studentid = ServletActionContext.getRequest().getParameter("studentid");
         studentSerivce.delByStudentId(studentid);
         //创建一个JSON对象
         JSONObject json = new JSONObject();
         json.put(“message",删除成功");//将返回信息保存在JSON对象中
         HttpServletResponse response = ServletActionContext.getResponse();
         //设置响应编码格式，防止乱码
         response.setContentType("text/html;charset=UTF-8");
         //将数据以json格式响应给ajax
         response.getWriter().write(json.toString());

         return null;
     }
 }