363 lines
10 KiB
JavaScript
363 lines
10 KiB
JavaScript
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/**
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* LRU 文件存储，使用该 downloader 可以让下载的文件存储在本地，下次进入小程序后可以直接使用
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* 详细设计文档可查看 https://juejin.im/post/5b42d3ede51d4519277b6ce3
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*/
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const util = require('./util');
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const sha1 = require('./sha1');
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const SAVED_FILES_KEY = 'savedFiles';
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const KEY_TOTAL_SIZE = 'totalSize';
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const KEY_PATH = 'path';
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const KEY_TIME = 'time';
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const KEY_SIZE = 'size';
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// 可存储总共为 6M，目前小程序可允许的最大本地存储为 10M
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let MAX_SPACE_IN_B = 6 * 1024 * 1024;
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let savedFiles = {};
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export default class Dowloader {
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constructor() {
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// app 如果设置了最大存储空间，则使用 app 中的
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if (getApp().PAINTER_MAX_LRU_SPACE) {
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MAX_SPACE_IN_B = getApp().PAINTER_MAX_LRU_SPACE;
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}
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wx.getStorage({
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key: SAVED_FILES_KEY,
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success: function (res) {
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if (res.data) {
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savedFiles = res.data;
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}
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},
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});
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}
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/**
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* 下载文件，会用 lru 方式来缓存文件到本地
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* @param {String} url 文件的 url
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*/
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download(url, lru) {
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return new Promise((resolve, reject) => {
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if (!(url && util.isValidUrl(url))) {
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resolve(url);
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return;
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}
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const fileName = getFileName(url);
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if (!lru) {
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// 无 lru 情况下直接判断 临时文件是否存在，不存在重新下载
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wx.getFileInfo({
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filePath: fileName,
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success: () => {
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resolve(url);
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},
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fail: () => {
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if (util.isOnlineUrl(url)) {
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downloadFile(url, lru).then((path) => {
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resolve(path);
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}, () => {
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reject();
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});
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} else if (util.isDataUrl(url)) {
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transformBase64File(url, lru).then(path => {
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resolve(path);
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}, () => {
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reject();
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});
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}
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},
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})
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return
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}
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const file = getFile(fileName);
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if (file) {
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if (file[KEY_PATH].indexOf('//usr/') !== -1) {
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wx.getFileInfo({
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filePath: file[KEY_PATH],
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success() {
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resolve(file[KEY_PATH]);
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},
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fail(error) {
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console.error(`base64 file broken, ${JSON.stringify(error)}`);
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transformBase64File(url, lru).then(path => {
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resolve(path);
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}, () => {
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reject();
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});
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}
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})
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} else {
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// 检查文件是否正常，不正常需要重新下载
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wx.getSavedFileInfo({
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filePath: file[KEY_PATH],
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success: (res) => {
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resolve(file[KEY_PATH]);
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},
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fail: (error) => {
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console.error(`the file is broken, redownload it, ${JSON.stringify(error)}`);
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downloadFile(url, lru).then((path) => {
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resolve(path);
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}, () => {
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reject();
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});
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},
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});
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}
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} else {
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if (util.isOnlineUrl(url)) {
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downloadFile(url, lru).then((path) => {
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resolve(path);
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}, () => {
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reject();
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});
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} else if (util.isDataUrl(url)) {
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transformBase64File(url, lru).then(path => {
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resolve(path);
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}, () => {
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reject();
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});
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}
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}
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});
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}
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}
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function getFileName(url) {
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if (util.isDataUrl(url)) {
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const [, format, bodyData] = /data:image\/(\w+);base64,(.*)/.exec(url) || [];
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const fileName = `${sha1.hex_sha1(bodyData)}.${format}`;
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return fileName;
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} else {
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return url;
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}
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}
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function transformBase64File(base64data, lru) {
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return new Promise((resolve, reject) => {
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const [, format, bodyData] = /data:image\/(\w+);base64,(.*)/.exec(base64data) || [];
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if (!format) {
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console.error('base parse failed');
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reject();
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return;
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}
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const fileName = `${sha1.hex_sha1(bodyData)}.${format}`;
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const path = `${wx.env.USER_DATA_PATH}/${fileName}`;
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const buffer = wx.base64ToArrayBuffer(bodyData.replace(/[\r\n]/g, ""));
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wx.getFileSystemManager().writeFile({
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filePath: path,
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data: buffer,
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encoding: 'binary',
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success() {
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wx.getFileInfo({
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filePath: path,
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success: (tmpRes) => {
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const newFileSize = tmpRes.size;
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lru ? doLru(newFileSize).then(() => {
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saveFile(fileName, newFileSize, path, true).then((filePath) => {
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resolve(filePath);
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});
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}, () => {
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resolve(path);
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}) : resolve(path);
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},
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fail: (error) => {
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// 文件大小信息获取失败，则此文件也不要进行存储
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console.error(`getFileInfo ${path} failed, ${JSON.stringify(error)}`);
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resolve(path);
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},
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});
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},
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fail(err) {
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console.log(err)
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}
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})
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});
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}
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function downloadFile(url, lru) {
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return new Promise((resolve, reject) => {
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const downloader = url.startsWith('cloud://')?wx.cloud.downloadFile:wx.downloadFile
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downloader({
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url: url,
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fileID: url,
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success: function (res) {
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if (res.statusCode !== 200) {
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console.error(`downloadFile ${url} failed res.statusCode is not 200`);
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reject();
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return;
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}
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const {
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tempFilePath
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} = res;
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wx.getFileInfo({
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filePath: tempFilePath,
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success: (tmpRes) => {
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const newFileSize = tmpRes.size;
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lru ? doLru(newFileSize).then(() => {
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saveFile(url, newFileSize, tempFilePath).then((filePath) => {
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resolve(filePath);
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});
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}, () => {
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resolve(tempFilePath);
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}) : resolve(tempFilePath);
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},
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fail: (error) => {
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// 文件大小信息获取失败，则此文件也不要进行存储
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console.error(`getFileInfo ${res.tempFilePath} failed, ${JSON.stringify(error)}`);
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resolve(res.tempFilePath);
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},
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});
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},
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fail: function (error) {
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console.error(`downloadFile failed, ${JSON.stringify(error)} `);
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reject();
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},
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});
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});
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}
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function saveFile(key, newFileSize, tempFilePath, isDataUrl = false) {
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return new Promise((resolve, reject) => {
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if (isDataUrl) {
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const totalSize = savedFiles[KEY_TOTAL_SIZE] ? savedFiles[KEY_TOTAL_SIZE] : 0;
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savedFiles[key] = {};
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savedFiles[key][KEY_PATH] = tempFilePath;
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savedFiles[key][KEY_TIME] = new Date().getTime();
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savedFiles[key][KEY_SIZE] = newFileSize;
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savedFiles['totalSize'] = newFileSize + totalSize;
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wx.setStorage({
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key: SAVED_FILES_KEY,
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data: savedFiles,
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});
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resolve(tempFilePath);
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return;
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}
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wx.saveFile({
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tempFilePath: tempFilePath,
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success: (fileRes) => {
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const totalSize = savedFiles[KEY_TOTAL_SIZE] ? savedFiles[KEY_TOTAL_SIZE] : 0;
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savedFiles[key] = {};
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savedFiles[key][KEY_PATH] = fileRes.savedFilePath;
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savedFiles[key][KEY_TIME] = new Date().getTime();
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savedFiles[key][KEY_SIZE] = newFileSize;
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savedFiles['totalSize'] = newFileSize + totalSize;
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wx.setStorage({
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key: SAVED_FILES_KEY,
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data: savedFiles,
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});
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resolve(fileRes.savedFilePath);
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},
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fail: (error) => {
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console.error(`saveFile ${key} failed, then we delete all files, ${JSON.stringify(error)}`);
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// 由于 saveFile 成功后，res.tempFilePath 处的文件会被移除，所以在存储未成功时，我们还是继续使用临时文件
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resolve(tempFilePath);
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// 如果出现错误，就直接情况本地的所有文件，因为你不知道是不是因为哪次lru的某个文件未删除成功
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reset();
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},
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});
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});
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}
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/**
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* 清空所有下载相关内容
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*/
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function reset() {
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wx.removeStorage({
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key: SAVED_FILES_KEY,
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success: () => {
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wx.getSavedFileList({
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success: (listRes) => {
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removeFiles(listRes.fileList);
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},
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fail: (getError) => {
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console.error(`getSavedFileList failed, ${JSON.stringify(getError)}`);
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},
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});
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},
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});
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}
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function doLru(size) {
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if (size > MAX_SPACE_IN_B) {
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return Promise.reject()
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}
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return new Promise((resolve, reject) => {
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let totalSize = savedFiles[KEY_TOTAL_SIZE] ? savedFiles[KEY_TOTAL_SIZE] : 0;
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if (size + totalSize <= MAX_SPACE_IN_B) {
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resolve();
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return;
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}
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// 如果加上新文件后大小超过最大限制，则进行 lru
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const pathsShouldDelete = [];
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// 按照最后一次的访问时间，从小到大排序
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const allFiles = JSON.parse(JSON.stringify(savedFiles));
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delete allFiles[KEY_TOTAL_SIZE];
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const sortedKeys = Object.keys(allFiles).sort((a, b) => {
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return allFiles[a][KEY_TIME] - allFiles[b][KEY_TIME];
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});
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for (const sortedKey of sortedKeys) {
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totalSize -= savedFiles[sortedKey].size;
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pathsShouldDelete.push(savedFiles[sortedKey][KEY_PATH]);
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delete savedFiles[sortedKey];
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if (totalSize + size < MAX_SPACE_IN_B) {
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break;
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}
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}
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savedFiles['totalSize'] = totalSize;
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wx.setStorage({
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key: SAVED_FILES_KEY,
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data: savedFiles,
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success: () => {
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// 保证 storage 中不会存在不存在的文件数据
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if (pathsShouldDelete.length > 0) {
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removeFiles(pathsShouldDelete);
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}
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resolve();
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},
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fail: (error) => {
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console.error(`doLru setStorage failed, ${JSON.stringify(error)}`);
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reject();
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},
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});
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});
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}
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function removeFiles(pathsShouldDelete) {
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for (const pathDel of pathsShouldDelete) {
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let delPath = pathDel;
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if (typeof pathDel === 'object') {
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delPath = pathDel.filePath;
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}
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if (delPath.indexOf('//usr/') !== -1) {
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wx.getFileSystemManager().unlink({
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filePath: delPath,
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fail(error) {
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console.error(`removeSavedFile ${pathDel} failed, ${JSON.stringify(error)}`);
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}
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})
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} else {
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wx.removeSavedFile({
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filePath: delPath,
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fail: (error) => {
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console.error(`removeSavedFile ${pathDel} failed, ${JSON.stringify(error)}`);
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},
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});
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}
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}
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}
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function getFile(key) {
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if (!savedFiles[key]) {
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return;
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}
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savedFiles[key]['time'] = new Date().getTime();
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wx.setStorage({
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key: SAVED_FILES_KEY,
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data: savedFiles,
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});
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return savedFiles[key];
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}
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