[]安卓无法调用后置摄像头

navigator.mediaDevices.enumerateDevices().then(function (devices) {

            var userMediaConstraints = {

                audio: false,

                video: {

                    facingMode: {exact : 'environment'},

                }

            }

            navigator.mediaDevices.getUserMedia(userMediaConstraints).then(function success(stream) {

                let status = true;

                LayaAir3D.video.srcObject = stream;

                LayaAir3D.video.play();

                /** 等到视频流准备就绪 */

                var interval = setInterval(function () {

                    if (!LayaAir3D.video.videoWidth) {

                        return;

                    }

                    laya.utils.Browser.document.body.appendChild(LayaAir3D.video);

                    clearInterval(interval);

                }, 1000 / 50);

            });

        }).catch(function (error) {

            onError({

                message: error.message

            });

        });