/// <summary>
  /// 生成随机验证码
  /// </summary>
  public static class RandomCode
  {
    /// <summary>
    /// 返回一个N位验证码
    /// </summary>
    /// <param name="N">位数</param>
    /// <returns></returns>
    public static string RandomCodeCommand(int N)
    {
      string code = "";
      Random random = new Random();
      for (int i = 0; i < N; i++)
      {
        code += random.Next(9);
      }
      return code;
    }
  }

public class SendRandomCode : ViewModelBase
  {
    private int _interval;//记录倒计时长
    private string idCode;//在规定时间内保存验证码
    private int idCodeTime;//设置验证码的有效时间（秒）
    private int idCodeNum = 6;//设置验证码的位数

    public void GetCode(string phoneNum)
    {
      //获取验证码
      timerSend = new Timer(1000);
      timerSend.AutoReset = true;
      timerSend.Elapsed += Timer_Elapsed;
      _interval = SecondNum;
      timerSend.Start();

      //在验证码有效期内，再次请求验证码，需要先关闭上一次的
      if (timerTime != null)
      {
        timerTime.Close();
        timerTime.Dispose();
      }
      //验证码的有效期
      timerTime = new Timer(1000);
      timerTime.AutoReset = true;
      timerTime.Elapsed += TimerTime_Elapsed;
      timerTime.Start();
      idCodeTime = SaveTime;
      IdCode = RandomCode.RandomCodeCommand(idCodeNum);
      PhoneNum = phoneNum;
    }

    #region 获取验证码倒计时
    Timer timerSend;
    Timer timerTime;
    private void Timer_Elapsed(object sender, ElapsedEventArgs e)
    {
      BtnIsEnable = false;
      BtnContent = "(" + (_interval--) + ")秒后再次获取验证码";

      if (_interval <= -1)
      {
        BtnIsEnable = true;
        BtnContent = "获取验证码";
        timerSend.Stop();
        timerSend.Dispose();
      }
      //throw new NotImplementedException();
    }
    private void TimerTime_Elapsed(object sender, ElapsedEventArgs e)
    {
      idCodeTime--;
      if (idCodeTime <= 0)
      {
        IdCode = "";
        timerTime.Stop();
        timerTime.Dispose();
      }
      Console.WriteLine(IdCode);
      //throw new NotImplementedException();
    }
    #endregion

    #region 字段
    //*************************************************************************************************//上线时需要修改
    private int secondNum = 30;//设置倒计时长
    private int saveTime = 60;//设置保存验证码时长
                 //*************************************************************************************************//
    private string btnContent = "获取验证码";//设置获取验证码按钮显示的名称
    private bool btnIsEnable = true;//设置获取验证码按钮是否可用

    private string phoneNum;//记录是否是发送验证码的手机号
    public int SecondNum
    {
      get
      {
        return secondNum;
      }

      set
      {
        secondNum = value;
      }
    }

    public int SaveTime
    {
      get
      {
        return saveTime;
      }

      set
      {
        saveTime = value;
      }
    }

    public string BtnContent
    {
      get
      {
        return btnContent;
      }

      set
      {
        btnContent = value;
        RaisePropertyChanged("BtnContent");
      }
    }

    public bool BtnIsEnable
    {
      get
      {
        return btnIsEnable;
      }

      set
      {
        btnIsEnable = value;
        RaisePropertyChanged("BtnIsEnable");
      }
    }

    public string IdCode
    {
      get
      {
        return idCode;
      }

      set
      {
        idCode = value;
        RaisePropertyChanged("IdCode");
      }
    }

    public string PhoneNum
    {
      get
      {
        return phoneNum;
      }

      set
      {
        phoneNum = value;
        RaisePropertyChanged("PhoneNum");
      }
    }
    #endregion
  }

<Grid>
    <Grid.RowDefinitions>
      <RowDefinition/>
      <RowDefinition/>
    </Grid.RowDefinitions>
    <StackPanel Grid.Row="0" HorizontalAlignment="Center" VerticalAlignment="Center" Orientation="Horizontal">
      <Label Content="手机号"/>
      <TextBox Text="{Binding PhoneNum}" Height="20" Width="100"/>
      <Button Content="{Binding Src.BtnContent}" IsEnabled="{Binding Src.BtnIsEnable}" Command="{Binding SendCode}" Height="20" Width="120"/>
    </StackPanel>
    <StackPanel Grid.Row="1" HorizontalAlignment="Center" VerticalAlignment="Center" Orientation="Horizontal">
      <Label Content="验证码"/>
      <TextBox Text="{Binding IdentifyCode}" Height="20" Width="100"/>
      <Button Content="提交" Command="{Binding Submit}" Height="20" Width="120"/>
    </StackPanel>
  </Grid>

public class BingVM: ViewModelBase
  {
    #region 界面字段
    private string phoneNum;//手机号
    private string identifyCode;//验证码
    public string PhoneNum
    {
      get
      {
        return phoneNum;
      }

      set
      {
        phoneNum = value;
        RaisePropertyChanged("PhoneNum");
      }
    }

    public string IdentifyCode
    {
      get
      {
        return identifyCode;
      }

      set
      {
        identifyCode = value;
        RaisePropertyChanged("IdentifyCode");
      }
    }
    #endregion

    #region 为获取验证码按钮设置content和isEnable用的
    SendRandomCode src = new SendRandomCode();
    public SendRandomCode Src
    {
      get { return src; }
      set
      {
        src = value;
      }
    }
    #endregion

    private RelayCommand sendCode;//获取验证码

    public RelayCommand SendCode
    {
      get
      {
        return sendCode ?? (sendCode = new RelayCommand(
          () =>
          {
            if (!string.IsNullOrEmpty(PhoneNum))
            {
              src.GetCode(PhoneNum);
            }
            else
            {
              MessageBox.Show("手机号不能为空！");
            }

          }));
      }
    }
    private RelayCommand submit;

    public RelayCommand Submit
    {
      get
      {
        return submit ?? (submit = new RelayCommand(
          () =>
          {
            if (IdentifyCode == src.IdCode && PhoneNum == src.PhoneNum)
            {
              MessageBox.Show("验证成功");
            }
            else
            {
              MessageBox.Show("验证失败");
            }
          }));
      }
    }

  }