【HarmonyOS】 鸿蒙保存图片或视频到相册
前言
鸿蒙中保存图片或者视频，或者其他媒体文件到设备的媒体库，可以是相册，也可以是文件管理等。共有两种方式：
- 需要应用申请受限权限，获取文件读写的权限（调用需要ohos.permission.READ_IMAGEVIDEO和ohos.permission.WRITE_IMAGEVIDEO的权限），这样就可以将媒体资源（图片or视频or等等）保存到媒体库。
- 通过安全控件，用户触发后表示同意，可以临时授权给应用就行保存处理。
关于第二种安全控件，又分为saveButton保存按钮和showAssetsCreationDialog授权弹框两种形式。前者的按钮样式不能自定义，所以后者以弹框的形式，让用户操作，触发入口的样式，应用就可以自定义了。后者算是前者的一种替代补充。
一、保存图片和视频授权示例
需要申请"ohos.permission.READ_IMAGEVIDEO"和"ohos.permission.WRITE_IMAGEVIDEO"权限。该权限是管制权限，需要你的应用去通过场景申请【申请使用受限权限】
配置权限READ_IMAGEVIDEO，WRITE_IMAGEVIDEO
"requestPermissions": [{"name": "ohos.permission.READ_IMAGEVIDEO","usedScene": {"abilities": ["EntryAbility"],"when": "inuse"},"reason": "$string:CAMERA"},{"name": "ohos.permission.WRITE_IMAGEVIDEO","usedScene": {"abilities": ["EntryAbility"],"when": "inuse"},"reason": "$string:CAMERA"}
]
向用户申请权限
// 创建申请权限明细async reqPermissionsFromUser(): Promise<number[]> {let context = getContext() as common.UIAbilityContext;let atManager = abilityAccessCtrl.createAtManager();let grantStatus = await atManager.requestPermissionsFromUser(context, ['ohos.permission.READ_IMAGEVIDEO','ohos.permission.WRITE_IMAGEVIDEO']);return grantStatus.authResults;}// 用户申请权限async requestPermission() {let grantStatus = await this.reqPermissionsFromUser();for (let i = 0; i < grantStatus.length; i++) {if (grantStatus[i] === 0) {// 用户授权，可以继续访问目标操作}}}
保存图片到媒体库
public async savePicture(buffer: ArrayBuffer): Promise<void> {let helper : photoAccessHelper.PhotoAccessHelper = photoAccessHelper.getPhotoAccessHelper(getContext(this) as common.UIAbilityContext);let options: photoAccessHelper.CreateOptions = {title: Date.now().toString()};let photoUri: string = await helper.createAsset(photoAccessHelper.PhotoType.IMAGE, 'jpg', options);console.info(photoUri)// createAsset的调用需要ohos.permission.READ_IMAGEVIDEO和ohos.permission.WRITE_IMAGEVIDEO的权限let file: fs.File = fs.openSync(photoUri, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);await fs.write(file.fd, buffer);fs.closeSync(file);
}
二、saveButton示例
import { photoAccessHelper } from '@kit.MediaLibraryKit';
struct saveButtonExample {saveButtonOptions: SaveButtonOptions = {icon: SaveIconStyle.FULL_FILLED,text: SaveDescription.SAVE_IMAGE,buttonType: ButtonType.Capsule} // 设置安全控件按钮属性build() {Row() {Column() {SaveButton(this.saveButtonOptions) // 创建安全控件按钮.onClick(async (event, result: SaveButtonOnClickResult) => {if (result == SaveButtonOnClickResult.SUCCESS) {try {let context = getContext();let phAccessHelper = photoAccessHelper.getPhotoAccessHelper(context);// 需要确保fileUri对应的资源存在let fileUri = 'file://com.example.temptest/data/storage/el2/base/haps/entry/files/test.jpg';let assetChangeRequest: photoAccessHelper.MediaAssetChangeRequest = photoAccessHelper.MediaAssetChangeRequest.createImageAssetRequest(context, fileUri);await phAccessHelper.applyChanges(assetChangeRequest);console.info('createAsset successfully, uri: ' + assetChangeRequest.getAsset().uri);} catch (err) {console.error(`create asset failed with error: ${err.code}, ${err.message}`);}} else {console.error('SaveButtonOnClickResult create asset failed');}})}.width('100%')}.height('100%')}
}
三、 showAssetsCreationDialog示例
import { photoAccessHelper } from '@kit.MediaLibraryKit';
import { fileIo } from '@kit.CoreFileKit';let context = getContext(this);
let phAccessHelper = photoAccessHelper.getPhotoAccessHelper(context);async function showAssetsCreationDialogExample() {try {// 指定待保存到媒体库的位于应用沙箱的图片urilet srcFileUri = 'file://com.example.temptest/data/storage/el2/base/haps/entry/files/test.jpg';let srcFileUris: Array<string> = [srcFileUri];// 指定待保存照片的创建选项，包括文件后缀和照片类型，标题和照片子类型可选let photoCreationConfigs: Array<photoAccessHelper.PhotoCreationConfig> = [{title: 'test', // 可选fileNameExtension: 'jpg',photoType: photoAccessHelper.PhotoType.IMAGE,subtype: photoAccessHelper.PhotoSubtype.DEFAULT, // 可选}];// 基于弹窗授权的方式获取媒体库的目标urilet desFileUris: Array<string> = await phAccessHelper.showAssetsCreationDialog(srcFileUris, photoCreationConfigs);// 将来源于应用沙箱的照片内容写入媒体库的目标urilet desFile: fileIo.File = await fileIo.open(desFileUris[0], fileIo.OpenMode.WRITE_ONLY);let srcFile: fileIo.File = await fileIo.open(srcFileUri, fileIo.OpenMode.READ_ONLY);await fileIo.copyFile(srcFile.fd, desFile.fd);fileIo.closeSync(srcFile);fileIo.closeSync(desFile);console.info('create asset by dialog successfully');} catch (err) {console.error(`failed to create asset by dialog successfully errCode is: ${err.code}, ${err.message}`);}
}
注意：
1. 使用createAsset需要指定是视频还是图片， fileio.open并不校验文件内容
2. 使用createImageAssetRequest接口，如果要保存视频需要用createVideoeAssetRequest
或者还可以直接使用createAssetRequest和addResource的方式
