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使用文件前，先检查下文件是否正常

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This commit is contained in:
CPPAlien 2018-07-16 12:06:14 +08:00
parent ca17eb4844
commit 83195e6cad
1 changed files with 69 additions and 36 deletions
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105
lib/downloader.js
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@ -1,3 +1,7 @@
/**
* 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
* 详细设计文档可查看 https://juejin.im/post/5b42d3ede51d4519277b6ce3
*/
const util = require('./util');
const SAVED_FILES_KEY = 'savedFiles';
@ -7,11 +11,15 @@ const KEY_TIME = 'time';
const KEY_SIZE = 'size';
// 可存储总共为 6M，目前小程序可允许的最大本地存储为 10M
const MAX_SPACE_IN_B = 6 * 1024 * 1024;
let MAX_SPACE_IN_B = 6 * 1024 * 1024;
let savedFiles = {};
export default class Dowloader {
constructor() {
// app 如果设置了最大存储空间，则使用 app 中的
if (getApp().PAINTER_MAX_LRU_SPACE) {
MAX_SPACE_IN_B = getApp().PAINTER_MAX_LRU_SPACE;
}
wx.getStorage({
key: SAVED_FILES_KEY,
success: function (res) {
@ -33,47 +41,72 @@ export default class Dowloader {
return;
}
const file = getFile(url);
if (file) {
resolve(file[KEY_PATH]);
return;
}
wx.downloadFile({
url: url,
success: function (res) {
if (res.statusCode !== 200) {
console.error(`downloadFile ${url} failed res.statusCode is not 200`);
reject();
return;
}
const { tempFilePath } = res;
wx.getFileInfo({
filePath: tempFilePath,
success: (tmpRes) => {
const newFileSize = tmpRes.size;
doLru(newFileSize).then(() => {
saveFile(url, newFileSize, tempFilePath).then((filePath) => {
resolve(filePath);
});
}, () => {
resolve(tempFilePath);
});
},
fail: (error) => {
// 文件大小信息获取失败，则此文件也不要进行存储
console.error(`getFileInfo ${res.tempFilePath} failed, ${JSON.stringify(error)}`);
resolve(res.tempFilePath);
},
});
},
fail: function (error) {
console.error(`downloadFile failed, ${JSON.stringify(error)} `);
// 检查文件是否正常，不正常需要重新下载
wx.getSavedFileInfo({
filePath: file[KEY_PATH],
success: (res) => {
resolve(file[KEY_PATH]);
},
fail: (error) => {
console.error(`the file is broken, redownload it, ${JSON.stringify(error)}`);
downloadFile(url).then((path) => {
resolve(path);
}, () => {
reject();
});
},
});
} else {
downloadFile(url).then((path) => {
resolve(path);
}, () => {
reject();
},
});
});
}
});
}
}
function downloadFile(url) {
return new Promise((resolve, reject) => {
wx.downloadFile({
url: url,
success: function (res) {
if (res.statusCode !== 200) {
console.error(`downloadFile ${url} failed res.statusCode is not 200`);
reject();
return;
}
const { tempFilePath } = res;
wx.getFileInfo({
filePath: tempFilePath,
success: (tmpRes) => {
const newFileSize = tmpRes.size;
doLru(newFileSize).then(() => {
saveFile(url, newFileSize, tempFilePath).then((filePath) => {
resolve(filePath);
});
}, () => {
resolve(tempFilePath);
});
},
fail: (error) => {
// 文件大小信息获取失败，则此文件也不要进行存储
console.error(`getFileInfo ${res.tempFilePath} failed, ${JSON.stringify(error)}`);
resolve(res.tempFilePath);
},
});
},
fail: function (error) {
console.error(`downloadFile failed, ${JSON.stringify(error)} `);
reject();
},
});
});
}
function saveFile(key, newFileSize, tempFilePath) {
return new Promise((resolve, reject) => {
wx.saveFile({