使用For循环对Java中的Qr代码扫描器进行计数

如何解决使用For循环对Java中的Qr代码扫描器进行计数

我正在从这里使用Qr码扫描仪：https://github.com/mebjas/html5-qrcode

我成功启动了扫描仪，它将返回结果。

我要实现的结果是扫描11次qr代码，并将其追加到列表中。

PS：由于使用Framework7自定义DOM，因此请调用$$

我尝试循环它：

$$(document).on('click','#skvqr',function () {
  Html5Qrcode.getCameras().then(devices => {
    /**
     * devices would be an array of objects of type:
     * { id: "id",label: "label" }
     */
    if (devices && devices.length) {
      var cameraId = devices[1].id;
      // .. use this to start scanning.

      const html5QrCode = new Html5Qrcode(/* element id */ "reader");
      html5QrCode.start(
        cameraId,{
          fps: 10,// Optional frame per seconds for qr code scanning
          qrBox: 200  // Optional if you want bounded Box UI
        },qrCodeMessage => {
          // do something when code is read
          alert("scan succesful " + qrCodeMessage)
          for (i = 11; i >= 1; --i) {
            alert("scan succesful " + qrCodeMessage + " Press Ok and Scan " + i + " more times")
  
             $$("#qr-scan-3").append('<input type="text" value=" ' + 'SKV : ' + qrCodeMessage + ' " placeholder="Qr Scan 1">' +
            '<span class="input-clear-button"></span>'
          );
          this.style.display = 'none'
          html5QrCode.stop().then(ignore => {
            // QR Code scanning is stopped.
          }).catch(err => {
            // Stop Failed,handle it.
          });

          }

         
        },errorMessage => {
          // parse error,ignore it.
        })
        .catch(err => {
          // Start Failed,handle it.
        });
    }
    // ------------------------------------------------------------------------
  }).catch(err => {
    // handle err
  });
});

它会给我11次警告

("scan succesful " + qrCodeMessage + " Press Ok and Scan " + i + " more times")

，它只会第一次扫描。

请帮助我，仍然在学习JavaScript

解决方法

看起来您需要保持对成功回调全局的状态。

// define the scanner object
const html5QrCode = new Html5Qrcode(/* element id */ "reader");

let matchesFound = 0;
const totalScansNeeded = 11;
var successCallback = qrCodeMessage => {
    matchesFound++;
    if (matchesFound < totalScansNeeded) {
        let remainingScans = totalScansNeeded - matchesFound;
        alert(`scan successful ${qrCodeMessage}. Press Ok `
            + `and Scan ${remainingScans} more times"`);
    } else {
        // .. expected matches found
        // .. do required UI changes
        html5QrCode.stop().then(ignore => {
          // QR Code scanning is stopped.
        }).catch(err => {
          // Stop failed,handle it.
        });
    }
}

然后在实际的侦听器中使用它

$$(document).on('click','#skvqr',function () {
  Html5Qrcode.getCameras().then(devices => {
    if (devices && devices.length) {
      var cameraId = devices[1].id;
      html5QrCode.start(
        cameraId,{ fps: 10,qrbox: 200 },successCallback)
        .catch(err => {
          // Start failed,handle it.
        });
    }
  });
});