使用<video>标签显示相机画面，并通过调用navigator.mediaDevices.getUserMedia()方法获取用户媒体流，然后通过srcObject属性将媒体流赋值给<video>元素的srcObject属性，即可自动显示相机画面。
通过添加一个按钮，当点击按钮时，通过判断当前相机的facingMode状态（”user”表示前置摄像头，”environment”表示后置摄像头），然后调用navigator.mediaDevices.getUserMedia()方法切换到对应的摄像头，再将获取到的媒体流赋值给<video>元素的srcObject属性，即可实现前后摄像头的切换功能。
完整代码：
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<!DOCTYPE html><html><head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <title>Camera H5</title></head><body> <!-- 用于显示相机视频的<video>元素 --> <video id="video" autoplay playsinline></video> <!-- 用于切换前后摄像头的按钮 --> <button id="switchButton">Switch Camera</button> <script> // 获取视频元素和切换按钮元素 var video = document.getElementById("video"); var switchButton = document.getElementById("switchButton"); // 获取用户媒体流并显示相机画面 navigator.mediaDevices.getUserMedia({ video: { facingMode: "environment" } }) .then(function (stream) { video.srcObject = stream; }) .catch(function (error) { console.log("Error accessing camera: " + error); }); // 切换前后摄像头 switchButton.addEventListener("click", function () { if (video.srcObject) { var videoTracks = video.srcObject.getVideoTracks(); if (videoTracks.length > 0) { var facingMode = videoTracks[0].getSettings().facingMode; var newFacingMode = (facingMode === "user") ? "environment" : "user"; navigator.mediaDevices.getUserMedia({ video: { facingMode: newFacingMode } }) .then(function (stream) { video.srcObject = stream; }) .catch(function (error) { console.log("Error switching camera: " + error); }); } } }); </script></body></html> |