1# 音频播放流管理 2 3对于播放音频类的应用，开发者需要关注该应用的音频流的状态以做出相应的操作，比如监听到状态为播放中/暂停时，及时改变播放按钮的UI显示。 4 5## 读取或监听应用内音频流状态变化 6 7参考[使用AudioRenderer开发音频播放功能](using-audiorenderer-for-playback.md)或[audio.createAudioRenderer](../../reference/apis-audio-kit/js-apis-audio.md#audiocreateaudiorenderer8)，完成AudioRenderer的创建，然后可以通过以下两种方式查看音频流状态的变化： 8 9- 方法1：直接查看AudioRenderer的[state](../../reference/apis-audio-kit/js-apis-audio.md#属性)： 10 11 ```ts 12 import audio from '@ohos.multimedia.audio'; 13 14 let audioRendererState: audio.AudioState = audioRenderer.state; 15 console.info(`Current state is: ${audioRendererState }`) 16 ``` 17 18- 方法2：注册stateChange监听AudioRenderer的状态变化： 19 20 ```ts 21 import audio from '@ohos.multimedia.audio'; 22 23 audioRenderer.on('stateChange', (rendererState: audio.AudioState) => { 24 console.info(`State change to: ${rendererState}`) 25 }); 26 ``` 27 28获取state后可对照[AudioState](../../reference/apis-audio-kit/js-apis-audio.md#audiostate8)来进行相应的操作，比如更改暂停播放按钮的显示等。 29 30## 读取或监听所有音频流的变化 31 32如果部分应用需要查询获取所有音频流的变化信息，可以通过AudioStreamManager读取或监听所有音频流的变化。 33 34> **说明：** 35> 36> 对于标记为系统接口（system api）的音频流变化信息需要系统级别应用才可查看，若应用不是系统应用，将无法获取准确信息。 37 38如下为音频流管理调用关系图： 39 40 41 42在进行应用开发的过程中，开发者需要使用getStreamManager()创建一个AudioStreamManager实例，进而通过该实例管理音频流。开发者可通过调用on('audioRendererChange')监听音频流的变化，在音频流状态变化、设备变化时获得通知。同时可通过off('audioRendererChange')取消相关事件的监听。另外，开发者可以主动调用getCurrentAudioRendererInfoArray()来查询播放流的唯一ID、播放流客户端的UID、音频流状态等信息。 43 44详细API含义可参考[音频管理API文档AudioStreamManager](../../reference/apis-audio-kit/js-apis-audio.md#audiostreammanager9)。 45 46## 开发步骤及注意事项 47 481. 创建AudioStreamManager实例。 49 在使用AudioStreamManager的API前，需要使用getStreamManager()创建一个AudioStreamManager实例。 50 51 ```ts 52 import audio from '@ohos.multimedia.audio'; 53 54 let audioManager = audio.getAudioManager(); 55 let audioStreamManager = audioManager.getStreamManager(); 56 ``` 57 582. 使用on('audioRendererChange')监听音频播放流的变化。 如果音频流监听应用需要在音频播放流状态变化、设备变化时获取通知，可以订阅该事件。 59 60 ```ts 61 import audio from '@ohos.multimedia.audio'; 62 63 audioStreamManager.on('audioRendererChange', (AudioRendererChangeInfoArray: audio.AudioRendererChangeInfoArray) => { 64 for (let i = 0; i < AudioRendererChangeInfoArray.length; i++) { 65 let AudioRendererChangeInfo = AudioRendererChangeInfoArray[i]; 66 console.info(`## RendererChange on is called for ${i} ##`); 67 console.info(`StreamId for ${i} is: ${AudioRendererChangeInfo.streamId}`); 68 console.info(`Content ${i} is: ${AudioRendererChangeInfo.rendererInfo.content}`); 69 console.info(`Stream ${i} is: ${AudioRendererChangeInfo.rendererInfo.usage}`); 70 console.info(`Flag ${i} is: ${AudioRendererChangeInfo.rendererInfo.rendererFlags}`); 71 for (let j = 0;j < AudioRendererChangeInfo.deviceDescriptors.length; j++) { 72 console.info(`Id: ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].id}`); 73 console.info(`Type: ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].deviceType}`); 74 console.info(`Role: ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].deviceRole}`); 75 console.info(`Name: ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].name}`); 76 console.info(`Address: ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].address}`); 77 console.info(`SampleRates: ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].sampleRates[0]}`); 78 console.info(`ChannelCount ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].channelCounts[0]}`); 79 console.info(`ChannelMask: ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].channelMasks}`); 80 } 81 } 82 }); 83 ``` 84 853. （可选）使用off('audioRendererChange')取消监听音频播放流变化。 86 87 ```ts 88 audioStreamManager.off('audioRendererChange'); 89 console.info('RendererChange Off is called '); 90 ``` 91 924. （可选）使用getCurrentAudioRendererInfoArray()获取所有音频播放流的信息。 93 该接口可获取音频播放流唯一ID，音频播放客户端的UID，音频状态以及音频播放器的其他信息。 94 > **说明：** 95 > 96 > 对所有音频流状态进行监听的应用需要[声明权限](../../security/AccessToken/declare-permissions.md)ohos.permission.USE_BLUETOOTH，否则无法获得实际的设备名称和设备地址信息，查询到的设备名称和设备地址（蓝牙设备的相关属性）将为空字符串。 97 98 ```ts 99 import audio from '@ohos.multimedia.audio'; 100 import { BusinessError } from '@ohos.base'; 101 102 async function getCurrentAudioRendererInfoArray(): Promise<void> { 103 await audioStreamManager.getCurrentAudioRendererInfoArray().then((AudioRendererChangeInfoArray: audio.AudioRendererChangeInfoArray) => { 104 console.info(`getCurrentAudioRendererInfoArray Get Promise is called `); 105 if (AudioRendererChangeInfoArray != null) { 106 for (let i = 0; i < AudioRendererChangeInfoArray.length; i++) { 107 let AudioRendererChangeInfo = AudioRendererChangeInfoArray[i]; 108 console.info(`StreamId for ${i} is: ${AudioRendererChangeInfo.streamId}`); 109 console.info(`Content ${i} is: ${AudioRendererChangeInfo.rendererInfo.content}`); 110 console.info(`Stream ${i} is: ${AudioRendererChangeInfo.rendererInfo.usage}`); 111 console.info(`Flag ${i} is: ${AudioRendererChangeInfo.rendererInfo.rendererFlags}`); 112 for (let j = 0;j < AudioRendererChangeInfo.deviceDescriptors.length; j++) { 113 console.info(`Id: ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].id}`); 114 console.info(`Type: ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].deviceType}`); 115 console.info(`Role: ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].deviceRole}`); 116 console.info(`Name: ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].name}`); 117 console.info(`Address: ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].address}`); 118 console.info(`SampleRates: ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].sampleRates[0]}`); 119 console.info(`ChannelCount ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].channelCounts[0]}`); 120 console.info(`ChannelMask: ${i} : ${AudioRendererChangeInfo.deviceDescriptors[j].channelMasks}`); 121 } 122 } 123 } 124 }).catch((err: BusinessError ) => { 125 console.error(`Invoke getCurrentAudioRendererInfoArray failed, code is ${err.code}, message is ${err.message}`); 126 }); 127 } 128 ``` 129
