// 删除.
        // DELETE api/mydemo/5
        public void Delete(string id)
        {
            MyDemoUserInfo data = testUserList.FirstOrDefault(p => p.UserName == id);

            if (data != null)
            {
                testUserList.Remove(data);
            }
        }
        // 编辑
        // PUT api/mydemo/5
        public void Put(string id, [FromBody] MyDemoUserInfo mode)
        {
            MyDemoUserInfo data = testUserList.FirstOrDefault(p => p.UserName == id);

            if (data != null)
            {
                data.Password = mode.Password;
            }
        }
 // POST api/mydemo
 public void Post([FromBody] MyDemoUserInfo mode)
 {
     testUserList.Add(mode);
 }
 // POST api/<controller>
 public void Post([FromBody] MyDemoUserInfo value)
 {
     testUserList.Add(value);
 }