我是靠谱客的博主 失眠秋天,这篇文章主要介绍客户端将URL文件或图片通过jszip打包成zip压缩包,现在分享给大家,希望可以做个参考。

前言

项目开发过程中关于一个订单所有附件的导出引发的一个问题,刚开始的时候在后端打包并压缩,返回stream流给前端,前端通过a标签下载流,但是在文件比较大的时候会出现问题,后端压缩的时候采用的是archiver,前端压缩的时候采用的是jszip

服务端

archiver压缩返回流

压缩文件示例代码:
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let zip = archiver('zip') let zipFileCount = 0 // 读取文件 let resFile = request.get(f); // 获取文件扩展名 let fileExtension = f.split('.').pop(); // 添加压缩文件 zip.append(resFile, {name: `${filename}${index > 0 ? index : ''}.${fileExtension}`}); // 记录压缩文件个数 zipFileCount++; // 结束 zip.finalize();
返流示例代码:
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// 服务端采用nodejs的Koa2框架 ctx.attachment(attachmentFileName) ctx.body = zipFileStream

客户端

客户端通过OSS的URL链接将图片转为base64格式,再通过jszip插件将图片压缩,这样可以直接将压缩后的文件保存到客户端本地,服务端压力也会减小很多

图片URL转base64示例代码:
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/** * 图片链接转base64 * @param imgUrl * @returns {Promise<any>} */ export const getBase64 = (imgUrl) => { return new Promise(((resolve, reject) => { window.URL = window.URL || window.webkitURL; var xhr = new XMLHttpRequest(); xhr.open("get", imgUrl, true); // 至关重要 xhr.responseType = "blob"; xhr.onload = function () { if (this.status == 200) { //得到一个blob对象 var blob = this.response; // 至关重要 let oFileReader = new FileReader(); oFileReader.onloadend = function (e) { let base64 = e.target.result; resolve(base64) }; oFileReader.readAsDataURL(blob); } } xhr.send(); })) }

jszip接受的图片格式为base64格式,使用方式:

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img.file(name, imgData, {base64: true});
客户端压缩示例代码:
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let zip = new JSZip(); let img = zip.folder(`name`);// name为压缩后解压出来的文件的名字 img.file(name, imgData, {base64: true});// name为文件或图片的名字,记得带后缀 zip.generateAsync({type:"blob"}).then(function(content) { // see FileSaver.js saveAs(content, `zipName`);//压缩后的zip名 });

关于FileSaver.js

npm上有个file-saver的包,
其中有个FileSaver.js的文件,引用这个文件即可

示例
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import {saveAs} from '...FileSaver'
FileSaver.js
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/* FileSaver.js * A saveAs() FileSaver implementation. * 1.3.2 * 2016-06-16 18:25:19 * * By Eli Grey, http://eligrey.com * License: MIT * See https://github.com/eligrey/FileSaver.js/blob/master/LICENSE.md */ /*global self */ /*jslint bitwise: true, indent: 4, laxbreak: true, laxcomma: true, smarttabs: true, plusplus: true */ /*! @source http://purl.eligrey.com/github/FileSaver.js/blob/master/FileSaver.js */ var saveAs = saveAs || (function(view) { "use strict"; // IE <10 is explicitly unsupported if (typeof view === "undefined" || typeof navigator !== "undefined" && /MSIE [1-9]./.test(navigator.userAgent)) { return; } var doc = view.document // only get URL when necessary in case Blob.js hasn't overridden it yet , get_URL = function() { return view.URL || view.webkitURL || view; } , save_link = doc.createElementNS("http://www.w3.org/1999/xhtml", "a") , can_use_save_link = "download" in save_link , click = function(node) { var event = new MouseEvent("click"); node.dispatchEvent(event); } , is_safari = /constructor/i.test(view.HTMLElement) || view.safari , is_chrome_ios =/CriOS/[d]+/.test(navigator.userAgent) , throw_outside = function(ex) { (view.setImmediate || view.setTimeout)(function() { throw ex; }, 0); } , force_saveable_type = "application/octet-stream" // the Blob API is fundamentally broken as there is no "downloadfinished" event to subscribe to , arbitrary_revoke_timeout = 1000 * 40 // in ms , revoke = function(file) { var revoker = function() { if (typeof file === "string") { // file is an object URL get_URL().revokeObjectURL(file); } else { // file is a File file.remove(); } }; setTimeout(revoker, arbitrary_revoke_timeout); } , dispatch = function(filesaver, event_types, event) { event_types = [].concat(event_types); var i = event_types.length; while (i--) { var listener = filesaver["on" + event_types[i]]; if (typeof listener === "function") { try { listener.call(filesaver, event || filesaver); } catch (ex) { throw_outside(ex); } } } } , auto_bom = function(blob) { // prepend BOM for UTF-8 XML and text/* types (including HTML) // note: your browser will automatically convert UTF-16 U+FEFF to EF BB BF if (/^s*(?:text/S*|application/xml|S*/S*+xml)s*;.*charsets*=s*utf-8/i.test(blob.type)) { return new Blob([String.fromCharCode(0xFEFF), blob], {type: blob.type}); } return blob; } , FileSaver = function(blob, name, no_auto_bom) { if (!no_auto_bom) { blob = auto_bom(blob); } // First try a.download, then web filesystem, then object URLs var filesaver = this , type = blob.type , force = type === force_saveable_type , object_url , dispatch_all = function() { dispatch(filesaver, "writestart progress write writeend".split(" ")); } // on any filesys errors revert to saving with object URLs , fs_error = function() { if ((is_chrome_ios || (force && is_safari)) && view.FileReader) { // Safari doesn't allow downloading of blob urls var reader = new FileReader(); reader.onloadend = function() { var url = is_chrome_ios ? reader.result : reader.result.replace(/^data:[^;]*;/, 'data:attachment/file;'); var popup = view.open(url, '_blank'); if(!popup) view.location.href = url; url=undefined; // release reference before dispatching filesaver.readyState = filesaver.DONE; dispatch_all(); }; reader.readAsDataURL(blob); filesaver.readyState = filesaver.INIT; return; } // don't create more object URLs than needed if (!object_url) { object_url = get_URL().createObjectURL(blob); } if (force) { view.location.href = object_url; } else { var opened = view.open(object_url, "_blank"); if (!opened) { // Apple does not allow window.open, see https://developer.apple.com/library/safari/documentation/Tools/Conceptual/SafariExtensionGuide/WorkingwithWindowsandTabs/WorkingwithWindowsandTabs.html view.location.href = object_url; } } filesaver.readyState = filesaver.DONE; dispatch_all(); revoke(object_url); } ; filesaver.readyState = filesaver.INIT; if (can_use_save_link) { object_url = get_URL().createObjectURL(blob); setTimeout(function() { save_link.href = object_url; save_link.download = name; click(save_link); dispatch_all(); revoke(object_url); filesaver.readyState = filesaver.DONE; }); return; } fs_error(); } , FS_proto = FileSaver.prototype , saveAs = function(blob, name, no_auto_bom) { return new FileSaver(blob, name || blob.name || "download", no_auto_bom); } ; // IE 10+ (native saveAs) if (typeof navigator !== "undefined" && navigator.msSaveOrOpenBlob) { return function(blob, name, no_auto_bom) { name = name || blob.name || "download"; if (!no_auto_bom) { blob = auto_bom(blob); } return navigator.msSaveOrOpenBlob(blob, name); }; } FS_proto.abort = function(){}; FS_proto.readyState = FS_proto.INIT = 0; FS_proto.WRITING = 1; FS_proto.DONE = 2; FS_proto.error = FS_proto.onwritestart = FS_proto.onprogress = FS_proto.onwrite = FS_proto.onabort = FS_proto.onerror = FS_proto.onwriteend = null; return saveAs; }( typeof self !== "undefined" && self || typeof window !== "undefined" && window || this.content )); // `self` is undefined in Firefox for Android content script context // while `this` is nsIContentFrameMessageManager // with an attribute `content` that corresponds to the window if (typeof module !== "undefined" && module.exports) { module.exports.saveAs = saveAs; } else if ((typeof define !== "undefined" && define !== null) && (define.amd !== null)) { define("FileSaver.js", function() { return saveAs; }); }

最后

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