android - 在 webview 中更改为后置摄像头 (Android)

Question

我想用 HTML5 做一个应用程序，包括一个拍照系统。我刚刚包含了一个显示相机的代码:

mWebView.setWebChromeClient(new WebChromeClient() {
                @Override
                public void onPermissionRequest(final PermissionRequest request) {
                    KioskActivity.this.runOnUiThread(new Runnable(){
                        @TargetApi(Build.VERSION_CODES.LOLLIPOP)
                        @Override
                        public void run() {
                            request.grant(request.getResources());
                        }// run
                    });// MainActivity
                }// onPermissionRequest
            });// setWebChromeClient

但总是显示一个前置摄像头，我需要一个后置摄像头。你能帮我吗？谢谢。 :)

Answer 1

使用MediaDevices.enumerateDevices()确定后置摄像头:

navigator.mediaDevices.enumerateDevices().then(function(devices) {
  var cameras = [];
  devices.forEach(function(device) {
    'videoinput' === device.kind && cameras.push(device.deviceId);
  });
  // On my devices:
  // - cameras[0] - front camera;
  // - cameras[1] - back camera;
  var constraints = {video: {deviceId: {exact: cameras[1]}}};
  navigator.mediaDevices.getUserMedia(constraints).then(function(stream) {
    // Do something with stream.
  });
});

另请查看MediaTrackConstraints.facingMode .

在以下设备上测试:

• Mozilla/5.0 (Linux; Android 7.1.1; Pixel Build/NOF27B; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/56.0.2924.87 Mobile Safari/537.36
• Mozilla/5.0(Linux；Android 6.0.1；MotoG3 Build/MPI24.107-55-2；wv)AppleWebKit/537.36(KHTML，如 Gecko)Version/4.0 Chrome/56.0。 2924.87 移动 Safari/537.36
• Mozilla/5.0 (Linux; Android 6.0.1; Moto G Play Build/MPI24.241-2.35-1; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/56.0.2924.87 移动 Safari/537.36
• Mozilla/5.0(Linux；Android 6.0.1；ONE E1005 Build/MMB29M；wv)AppleWebKit/537.36(KHTML，如 Gecko)版本/4.0 Chrome/55.0.2883.91 Mobile Safari/537.36