onScan(e) {
      // 只允许从相机扫码
      wx.scanCode({
        onlyFromCamera: true,
        scanType: ['qrCode'],
        success: (res) => {
          wx.showModal({
            title: '提示',
            content: '识别内容：' + res.result
          });
        },
        fail: (err) => {
          console.error('扫码失败', err);
        },
        complete: () => {
          console.log('扫码操作完成');
        }
      });
    }
  }