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HarmonyOS媒体文件操作

news 2025/4/28 1:30:39

媒体文件操作是实际的业务场景中比较常用的操作，通常我们需要用户上传文件，然后对文件进行操作后，再上传服务器。本篇文章对HarmonyOS中对文件的获取以及基本操作进行说明。

图片文件操作

设置媒体权限

在操作媒体文件之前需要在module.josn5文件中配置对应的权限才能进行操作

{"requestPermissions": [{"name": "ohos.permission.READ_IMAGEVIDEO","reason": "$string:app_name","usedScene": {"abilities": ["EntryAbility"],"when": "inuse"},},{"name":'ohos.permission.WRITE_IMAGEVIDEO',"reason":"$string:app_name","usedScene":{"abilities":["EntryAbility"],"when":"inuse"	}}]
}

获取媒体文件

HarmonyOS提供了多种获取媒体文件的方式，可以根据业务场景自行选择。

获取系统的所有媒体资源

获取所有媒体资源可以使用PhotoAccessHelper API实现。
获取资源的流程如下

创建photoAccessHelper实例对象
调用phtotAccessHelper的getAssets方法

// 导入PhotoAccessHelper模块
import photoAccessHelper from '@ohos.file.photoAccessHelper';
import dataSharePredicates from '@ohos.data.dataSharePredicates';
@Component
export default struct Asset{fetchColumns: photoAccessHelper.PhotoKeys[] = [photoAccessHelper.PhotoKeys.DATE_ADDED,photoAccessHelper.PhotoKeys.SIZE]@State list:List[] = [];async aboutToAppear(): Promise<void> {const list = await this.getScreenShotList()}// 获取所有媒体资源async getAssets() {const photoAccess = this.getPhotoAccessHelper();const fetchResult = await photoAccess.getAssets({fetchColumns: this.fetchColumns,predicates: new dataSharePredicates.DataSharePredicates()});const photoAssets = await fetchResult.getAllObjects();return photoAssets}// 获取截图列表async getScreenShotList() {const list = await this.getAssets()return list.filter(item => item.displayName.includes('screenshot'))}// 获取PhotoAccessHelpergetPhotoAccessHelper() {return photoAccessHelper.getPhotoAccessHelper(getContext())}// 获取视频列表async getVideoList() {const list = await this.getAssets()return list.filter(item => item.photoType === photoAccessHelper.PhotoType.VIDEO)}// 获取大尺寸图片async getLargeList(){const list = await this.getAssets();return list.filter((item)=>{return item.get(photoAccessHelper.PhotoKeys.SIZE) >= 200 * 1000})}build() {}}

通过用户上传文件

通过用户上传文件可以通过PhotoAccessHelper模块的PhotoViewPicker实例对象通过手动的方式打开文件选择界面，也可以通过PhotoPicker组件的方式自动打开文件选择界面。
我们以PhotoPicker为例

import {PhotoPickerComponent,PickerController,PickerOptions
} from '@ohos.file.PhotoPickerComponent';
import photoAccessHelper from '@ohos.file.photoAccessHelper';
@Component
struct PhotoPicker{
@State selectedUri:string[] = []
@State pickerOptions:PickerOptions = new PickerOptions()
aboutToAppear(){// 初始化pickerOptions// 设置最大选择数量this.pickerOptions.maxSelectNumber= 5;// 设置显示的可选择的文件类型this.pickerOptions.MIMEType = photoAccessHelper.PhotoViewMIMETypes.IMAGE_VIDEO_TYPE
}build(){PhotoPickerComponent(pickerOptions:this.pickerOptions,onSelect:(uri:string)=>{// 用户选择文件后的回调this.selectedUri.push(uri);}onDeselect:(uri:string)=>{// 用户取消选择的回调this.selectedUri= this.selectedUri.filter((item:string)=> item !== uri)})}
}

压缩图片

获取图片之后，我们可以对图片进行一些操作，例如压缩、转换图片格式等。压缩图片使用的是Image模块，使用Image模块的imagePacker进行压缩。
压缩包图片的基本，流程如下

获取资源
创建imagePacker
创建imageSource
调用imagePacker的packing方法，进行压缩
把压缩后的文件写入文件系统
删除原文件

 // 压缩图片async compressFile(uri:string){const imagePacker = image.createImagePacker();const file = fileIo.openSync(uri)const imageSource = image.createImageSource(file.fd)const arraybuffer = await imagePacker.packing(imageSource,{format:'image/jpeg',quality:20})const phAccessHelper = this.getPhotoAccessHelper();const createAssetUri = await phAccessHelper.createAsset(photoAccessHelper.PhotoType.IMAGE,'jpg');const fd = fileIo.openSync(createAssetUri,fileIo.OpenMode.READ_WRITE);fileIo.writeSync(fd.fd,arraybuffer)fileIo.close(fd.fd);}

音频文件操作

权限设置

在操作媒体文件之前需要在module.josn5文件中配置对应的权限才能进行操作。

{
"requestPermissions": [{"name": "ohos.permission.MICROPHONE","reason": "$string:app_name","usedScene": {"abilities": ["EntryAbility"],"when": "inuse"}}]
}

录制音频

HarmonyOS提供了多种方式录制音频，本篇文章以AudioCapture为例。
AudioCapture录制声音的流程如下

创建AudioCapture
监听readData事件，在该事件的回调函数中将音频数据写入文件

import { audio } from "@kit.AudioKit"
import { fileIo } from "@kit.CoreFileKit";
interface Options {offset?:number;length?:number
}
@Component
export default struct RecordVoice{capture:audio.AudioCapturer|null = null;filePath:string = ''streamInfo:audio.AudioStreamInfo = {samplingRate:audio.AudioSamplingRate.SAMPLE_RATE_48000,channels:audio.AudioChannel.CHANNEL_2,sampleFormat:audio.AudioSampleFormat.SAMPLE_FORMAT_S16LE,encodingType:audio.AudioEncodingType.ENCODING_TYPE_RAW}capturerInfo:audio.AudioCapturerInfo = {source:audio.SourceType.SOURCE_TYPE_MIC,capturerFlags:0}audioCaptureOptions:audio.AudioCapturerOptions = {streamInfo:this.streamInfo,capturerInfo:this.capturerInfo}// 创建AudioCapturecreateAudioCapture(){audio.createAudioCapturer(this.audioCaptureOptions,(err,data)=>{if(err){return;}this.capture = data;// 获取当前上下文以便于获取文件目录const context = getContext()// 设置文件名const fileName = Date.now()// 拼接文件路径this.filePath = `${context.filesDir}/${fileName}.wav`const file = fileIo.openSync(this.filePath,fileIo.OpenMode.READ_WRITE | fileIo.OpenMode.CREATE)// 监听readData事件，将数据写入文件data.on('readData',(buffer:ArrayBuffer)=>{const options:Options = {offset:bufferSize,length:buffer.byteLength}fileIo.readSync(file.fd,buffer，options)})// 开始录制this.capture?.start();})}build(){Navigation(){Scroll(){Column(){Button('开始录音').onClick(()=>{if(!this.capture){this.createAudioCapture();}else {this.capture.start();})Button('结束录音').onClick(()=>{if(this.capture?.state === audio.AudioState.STATE_RUNNING){this.capture?.stop();this.capture = null;}})}}}}
}

播放音频

HarmonyOS提供了多种播放音频的方式，本篇以AudioRenderer为例。
AudioRenderer播放音频的流程如下

创建AudioRenderer
监听writeData事件，读取音频文件数据，将数据写入AudioRenderer

import { audio } from "@kit.AudioKit"
import { fileIo } from "@kit.CoreFileKit";
interface Options {offset?:number;length?:number
}
@Component
export default struct RecordVoice{filePath:string = ''// 创建AudioRenderercreateAudioRenderer(){const streamInfo:audio.AudioStreamInfo = {samplingRate:audio.AudioSamplingRate.SAMPLE_RATE_48000,channels:audio.AudioChannel.CHANNEL_2,sampleFormat:audio.AudioSampleFormat.SAMPLE_FORMAT_S16LE,encodingType:audio.AudioEncodingType.ENCODING_TYPE_RAW}const rendererInfo:audio.AudioRendererInfo = {usage:audio.StreamUsage.STREAM_USAGE_MOVIE,rendererFlags:0}const audioRendererOptions:audio.AudioRendererOptions = {streamInfo:streamInfo,rendererInfo:rendererInfo}audio.createAudioRenderer(audioRendererOptions,(err,data)=>{if(err){return;}const audioRenderer = data;// 读取文件const file = fileIo.openSync(this.filePath,fileIo.OpenMode.READ_ONLY)// 获取文件信息const fileStat = fileIo.statSync(file.fd);// 记录已经播放的数据大小let bufferSize = 0;audioRenderer.on('writeData',(buffer)=>{const options:Options = {offset:bufferSize,length:buffer.byteLength}// 读取文件，将文件数据写入AudioRendererfileIo.readSync(file.fd,buffer,options)bufferSize += buffer.byteLength;// 判断文件是否播放完毕if(bufferSize >= fileStat.size){audioRenderer.stop();}})audioRenderer.start();})}aboutToAppear(): void {}build(){Navigation(){Scroll(){Column(){Button('播放音频').onClick(()=>{this.createAudioRenderer();})}}}}
}