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1# 使用WebRTC进行Web视频会议
2
3Web组件可以通过W3C标准协议接口拉起摄像头和麦克风，通过[onPermissionRequest](../reference/apis-arkweb/ts-basic-components-web.md#onpermissionrequest9)接口接收权限请求通知，需在配置文件中声明相应的音频权限。
4
5- 使用摄像头和麦克风功能前请在module.json5中添加音频相关权限，权限的添加方法请参考[在配置文件中声明权限](../security/AccessToken/declare-permissions.md)。
6
7   ```json
8    // src/main/resources/base/element/string.json
9    {
10      "name": "reason_for_camera",
11      "value": "reason_for_camera"
12    },
13    {
14      "name": "reason_for_microphone",
15      "value": "reason_for_microphone"
16    }
17  ```
18
19  ```json
20    // src/main/module.json5
21    "requestPermissions":[
22      {
23        "name" : "ohos.permission.CAMERA",
24        "reason": "$string:reason_for_camera",
25        "usedScene": {
26          "abilities": [
27            "EntryAbility"
28          ],
29          "when":"inuse"
30        }
31      },
32      {
33        "name" : "ohos.permission.MICROPHONE",
34        "reason": "$string:reason_for_microphone",
35        "usedScene": {
36          "abilities": [
37            "EntryAbility"
38          ],
39          "when":"inuse"
40        }
41      }
42    ],
43   ```
44
45通过在JavaScript中调用W3C标准协议接口navigator.mediaDevices.getUserMedia()，该接口用于拉起摄像头和麦克风。constraints参数是一个包含了video和audio两个成员的MediaStreamConstraints对象，用于说明请求的媒体类型。
46
47在下面的示例中，点击前端页面中的开起摄像头按钮再点击onConfirm，打开摄像头和麦克风。
48
49- 应用侧代码。
50
51  ```ts
52  // xxx.ets
53  import { webview } from '@kit.ArkWeb';
54  import { BusinessError } from '@kit.BasicServicesKit';
55  import { abilityAccessCtrl } from '@kit.AbilityKit';
56
57  @Entry
58  @Component
59  struct WebComponent {
60    controller: webview.WebviewController = new webview.WebviewController()
61
62    aboutToAppear() {
63      // 配置Web开启调试模式
64      webview.WebviewController.setWebDebuggingAccess(true);
65      // 获取权限请求通知，点击onConfirm按钮后，拉起摄像头和麦克风。
66      let atManager = abilityAccessCtrl.createAtManager();
67      atManager.requestPermissionsFromUser(getContext(this), ['ohos.permission.CAMERA', 'ohos.permission.MICROPHONE'])
68        .then((data) => {
69          console.info('data:' + JSON.stringify(data));
70          console.info('data permissions:' + data.permissions);
71          console.info('data authResults:' + data.authResults);
72        }).catch((error: BusinessError) => {
73        console.error(`Failed to request permissions from user. Code is ${error.code}, message is ${error.message}`);
74      })
75    }
76
77    build() {
78      Column() {
79        Web({ src: $rawfile('index.html'), controller: this.controller })
80          .onPermissionRequest((event) => {
81            if (event) {
82              AlertDialog.show({
83                title: 'title',
84                message: 'text',
85                primaryButton: {
86                  value: 'deny',
87                  action: () => {
88                    event.request.deny();
89                  }
90                },
91                secondaryButton: {
92                  value: 'onConfirm',
93                  action: () => {
94                    event.request.grant(event.request.getAccessibleResource());
95                  }
96                },
97                cancel: () => {
98                  event.request.deny();
99                }
100              })
101            }
102          })
103      }
104    }
105  }
106  ```
107
108- 前端页面index.html代码。
109
110  ```html
111  <!-- index.html -->
112  <!DOCTYPE html>
113  <html>
114  <head>
115    <meta charset="UTF-8">
116  </head>
117  <body>
118  <video id="video" width="500px" height="500px" autoplay="autoplay"></video>
119  <canvas id="canvas" width="500px" height="500px"></canvas>
120  <br>
121  <input type="button" title="HTML5摄像头" value="开启摄像头" onclick="getMedia()"/>
122  <script>
123    function getMedia()
124    {
125      let constraints = {
126        video: {width: 500, height: 500},
127        audio: true
128      };
129      // 获取video摄像头区域
130      let video = document.getElementById("video");
131      // 返回的Promise对象
132      let promise = navigator.mediaDevices.getUserMedia(constraints);
133      // then()异步，调用MediaStream对象作为参数
134      promise.then(function (MediaStream) {
135        video.srcObject = MediaStream;
136        video.play();
137      });
138    }
139  </script>
140  </body>
141  </html>
142  ```