接上一篇文章juejin.cn/post/742918…
在Android开发中会遇到下载应用包等文件到本地存储卡中，在Harmony应用中实现这个需求的思路是
- 首先权限上，采用安全控件SaveButton的方式跳过申请受限开放权限ohos.permission.WRITE_IMAGEVIDEO；
- 本地存储卡的路径，使用picker.DocumentViewPicker获取；
- 使用request.agent.create创建一个Task，将网络文件下载到当前应用的沙箱目录下；
- 将沙箱目录中下载完成的文件拷贝到本地存储卡的路径中。
工具类的代码DownloadFileNew.ets如下（配上了注释）
import { common } from '@kit.AbilityKit';
import fs, { ReadOptions, WriteOptions } from '@ohos.file.fs';
import { BusinessError, request } from '@kit.BasicServicesKit';
import { fileIo, picker } from '@kit.CoreFileKit';
let TAG= "DownloadFileNew"
export class DownloadFileNew{
/**
* 获取应用沙箱存储目录 统一一下，方便APP设置页面删除
* @returns
*/
static getLocalCacheDir():string {
let cache_dir_name = "appfiles";
let cache_dir = getContext().cacheDir+"/"+cache_dir_name;
console.info(`createCacheDir cache_dir: ${cache_dir}`);
let existAppCacheDir = fileIo.accessSync(cache_dir,fileIo.AccessModeType.EXIST)
if (!existAppCacheDir) {
fileIo.mkdirSync(cache_dir, true);
}
return cache_dir
}
/**
* 下载文件到本地存储卡的下载等文件夹下
* @param context
* @param filePath
* @param callback
*/
public static downloadImagToDir(context:common.UIAbilityContext,filePath:string,callback:DownloadCallback){
console.info(`${TAG} downloadImagToDir imagePath: ${filePath}`);
if (!filePath.startsWith("http://")&&!filePath.startsWith("https://")) {
callback.onError()
return
}
let defaultName = `${Date.now().toString()}.dmg`
//1.获取本地存储卡的下载等文件夹 考虑用户体验友好，先让用户选择下载路径，再下载
DownloadFileNew.selectDocumentPath(`${defaultName}`).then(destFilePath =>{
if (!destFilePath||destFilePath.length<=0) {
console.info(`${TAG} downloadImagToDir 用户取消了`);
callback.onError()
return
}
//2.获取下载到的应用沙箱目录
let localCacheDir:string = DownloadFileNew.getLocalCacheDir()
let srcFilePath =`${localCacheDir}/${defaultName}`
//使用request.agent.create下载文件到沙箱目录
let config:request.agent.Config = {
action: request.agent.Action.DOWNLOAD,
url: filePath,
method: 'GET',
title: 'download',
mode: request.agent.Mode.BACKGROUND,
retry: true,
network: request.agent.Network.ANY,
saveas: srcFilePath,//这里要注意目录 API文档和官方文档都有详细说明
overwrite: true
}
try {
let startTime = 0
//this.downloadTask = await request.agent.create(context,config)
request.agent.create(context,config).then(downloadTask=>{
if (callback.onStart) {
callback.onStart()
}
downloadTask.on("progress",(progress: request.agent.Progress)=>{
console.info(`${TAG} downloadImagToDir progress = ${JSON.stringify(progress)}`);
if (progress) {
callback.inProgress(progress.processed,progress.sizes[0])
}
})
downloadTask.on("completed",(progress: request.agent.Progress)=>{
console.info(`${TAG} downloadImagToDir completed time=${Date.now()-startTime}`);
//deleteTask();
if (downloadTask&&downloadTask.config.saveas) {
try {
let srcFilePath = downloadTask.config.saveas
downloadTask.off('progress');
downloadTask.off('completed');
downloadTask.off('failed');
request.agent.remove(downloadTask.tid);
//3.将下载到应用沙箱目录中的文件 写到用户选择的存储卡中destFilePath
DownloadFileNew.saveToDestFilePath(srcFilePath,destFilePath).then(r=>{
if (r) {
callback.onSuccess(destFilePath)
}else {
callback.onError()
}
})
} catch (err) {
console.info(`${TAG} downloadImagToDir completed fail, err= ${JSON.stringify(err)}`);
callback.onError()
}
}else {
console.info(`${TAG} downloadImagToDir completed fail, onError downloadTask==null `);
callback.onError()
}
})
downloadTask.on("failed", async (progress)=>{
let taskInfo = await request.agent.show(downloadTask!.tid);
console.info(`${TAG} downloadImagToDir failed, resean = ${taskInfo.reason}, faults = ${JSON.stringify(taskInfo.faults)}`);
callback.onError()
})
downloadTask.on('pause', async (progress: request.agent.Progress) => {
if (downloadTask) {
let taskInfo = await request.agent.show(downloadTask.tid);
console.info(`${TAG} pause, resean = ${taskInfo.reason}, progress = ${progress.processed}, faults = ${JSON.stringify(taskInfo.faults)}`);
}
})
downloadTask.on('resume',async (progress: request.agent.Progress) => {
if (downloadTask) {
let taskInfo = await request.agent.show(downloadTask.tid);
console.info(`${TAG} resume, resean = ${taskInfo.reason}, progress = ${progress.processed}, faults = ${JSON.stringify(taskInfo.faults)}`)
}
})
startTime = Date.now()
downloadTask.start()
})
} catch (err) {
console.info(`${TAG} task err, err = ${JSON.stringify(err)}`)
callback.onError()
}
}).catch((err:Error)=>{
console.info(`${TAG} task err, err111 = ${JSON.stringify(err)}`)
callback.onError()
})
}
/**
* 获取本地存储卡的下载等文件夹
* @param defaultName 默认文件名称（包含后缀名），用户可以在选择弹窗中修改
* @returns
*/
static async selectDocumentPath(defaultName:string): Promise<string>{
try {
let DocumentSaveOptions = new picker.DocumentSaveOptions();
DocumentSaveOptions.newFileNames = [defaultName];
let documentPicker = new picker.DocumentViewPicker();
return documentPicker.save(DocumentSaveOptions).then(async (documentSaveResult) => {
console.info(`${TAG} DocumentViewPicker.save successfully, DocumentSaveResult uri:= ${JSON.stringify(documentSaveResult)}`)
let destFile =await fs.open(documentSaveResult[0], fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
console.info(`${TAG} start destFile: ${destFile.path}`);
return destFile.path
}).catch((err:BusinessError) => {
console.info(`${TAG} DocumentViewPicker.save failed with err: ${JSON.stringify(err)}`);
return ""
});
} catch (err) {
console.info(`${TAG} DocumentViewPicker failed with err: ${JSON.stringify(err)}`);
return ""
}
}
/**
* 拷贝文件 从沙箱目录中到目标文件中
* @param srcFilePath 沙箱目录中文件
* @param destFilePath
* @returns
*/
static async saveToDestFilePath(srcFilePath:string,destFilePath:string){
console.info(`${TAG} saveToDestFilePath srcFilePath= ${srcFilePath},destFilePath= ${destFilePath}`);
try {
let bufSize = 4096;
let readSize = 0;
let srcFile = fs.openSync(srcFilePath, fs.OpenMode.READ_WRITE);
console.info(`${TAG} saveToDestFilePath srcFile: ${srcFile.path} size=`+ DownloadFileNew.bytesToMB(fs.statSync(srcFile.path).size));
let destFile = fs.openSync(destFilePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
console.info(`${TAG} saveToDestFilePath destFile: ${destFile.path}`);
let buf = new ArrayBuffer(bufSize);
let readOptions: ReadOptions = {
offset: readSize,
length: bufSize
};
let startTime = Date.now()
let readLen = fs.readSync(srcFile.fd, buf, readOptions);
console.info(`${TAG} readSync readLen: ${readLen}`);
while (readLen > 0) {
readSize += readLen;
let writeOptions: WriteOptions = {
length: readLen
};
fs.writeSync(destFile.fd, buf, writeOptions);
readOptions.offset = readSize;
readLen = fs.readSync(srcFile.fd, buf, readOptions);
}
console.info(`${TAG} write successfully 1111111 time=${Date.now()-startTime}`);
//fs.unlinkSync(srcFile.path) //删除沙箱目录中的临时文件
fs.closeSync(srcFile);
fs.closeSync(destFile);
console.info(`${TAG} close successfully 2222222 time=${Date.now()-startTime}`);
return true
} catch (err) {
console.info(`${TAG} saveToDestFilePath failed with err: ${JSON.stringify(err)}`);
return false
}
}
public static bytesToMB(bytes:number){
if(bytes>=1000){
bytes=bytes/1000.0;
if(bytes>=1000){
bytes=bytes/1000.0;
if(bytes>=1000){
bytes=bytes/1000.0;
return bytes+" GB";
}else{
return bytes+" MB";
}
}else{
return bytes+" KB";
}
}else{
return bytes+" Byte";
}
}
}
/**
* 下载文件的返回结果
*/
interface DownloadCallback {
onError: () => void;
onStart?: () => void;
inProgress: (progress: number, total: number) => void;
onSuccess: (file: string) => void;
}
调用侧逻辑代码
import { common } from '@kit.AbilityKit';
import { DownloadFileNew } from './DownloadFileNew';
import { Decimal } from '@kit.ArkTS';
@Entry
@Component
struct Index {
@State message: string = 'Hello World';
//网上自己找一个大的文件
fileUri = "https://4980bb6043e153a06db675f2cd6ce1f7.dlied1.cdntips.net/dldir1.qq.com/weixin/mac/WeChatMac.dmg?mkey=lego_ztc&f=00&sche_type=7&cip=118.113.101.171&proto=https"
@State fileDownHint: string = '0%';
@State saveButtonOptions: SaveButtonOptions = {
icon: SaveIconStyle.FULL_FILLED,
text: SaveDescription.SAVE_FILE,
buttonType: ButtonType.Capsule
} // 设置安全控件按钮属性
build() {
Column() {
Text(`${this.fileDownHint}`)
.textOverflow({ overflow: TextOverflow.None })
.fontSize(20)
.textAlign(TextAlign.Center)
.fontColor(Color.Black)
.width("100%")
.margin(40)
.fontWeight(FontWeight.Bold)
SaveButton(this.saveButtonOptions)
.width(100)
.height(50)
.onClick(async (event, result: SaveButtonOnClickResult) => {
if (result == SaveButtonOnClickResult.SUCCESS) {
DownloadFileNew.downloadImagToDir(getContext(this) as common.UIAbilityContext, this.fileUri, {
onError: () => {
},
inProgress: (progress, total) => {
let progressDecimal: Decimal = new Decimal(progress/total*100);
let progressFixed = progressDecimal.toFixed(2)
this.fileDownHint = `下载中：${progressFixed}%`
},
onSuccess: (file) => {
this.fileDownHint = `下载完成100%，文件地址：${file}`
}
})
}
})
}
.height('100%')
}
}
效果图
