JavaScript Base64 作為檔案上傳的例項程式碼解析
阿新 • • 發佈：2018-11-27
這篇文章主要介紹了JavaScript Base64 作為檔案上傳的例項程式碼解析,非常不錯，具有參考借鑑價值，需要的朋友可以參考下。
例如我們用某些 裁剪外掛 得到的圖片是 ：
<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAAkCAYAAABIdFAMAAAAGXRFWHRTb2Z0d2FyZQBBZG9iZSBJbWFnZVJlYWR5ccllPAAAAHhJREFUeNo8zjsOxCAMBFB/ KEAUFFR0Cbng3nQPw68ArZdAlOZppPFIBhH5EAB8b+Tlt9MYQ6i1BuqFaq1CKSVcxZ2Acs6406KUgpt5/ LCKuVgz5BDCSb13ZO99ZOdcZGvt4mJjzMVKqcha68iIePB86GAiOv8CDADlIUQBs7MD3wAAAABJRU5ErkJggg==">
這樣的，那這樣的檔案怎樣在from 表單上傳（當然我是舉例，大部分的裁剪外掛都是有內建的）
首先需要把 base64 流轉換成 blob 物件，檔案物件都繼承它。
函式如下：
function getBlobBydataURI(dataURI,type) { var binary = atob(dataURI.split(',')[1]); var array = []; for(var i = 0; i < binary.length; i++) { array.push(binary.charCodeAt(i)); } return new Blob([new Uint8Array(array)], {type:type }); }
那麼剩下的就作為檔案上傳就ok
var $Blob= getBlobBydataURI(base64Data,'image/png');
var formData = new FormData();
formData.append("files", $Blob ,"file_"+Date.parse(new Date())+".png");全部程式碼是這樣子的：
<!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <title>上傳用例</title> <meta content='width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no' name='viewport'> <script type="text/javascript"> /** * 根據base64 內容 取得 bolb * * @param dataURI * @returns Blob */ function getBlobBydataURI(dataURI,type) { var binary = atob(dataURI.split(',')[1]); var array = []; for(var i = 0; i < binary.length; i++) { array.push(binary.charCodeAt(i)); } return new Blob([new Uint8Array(array)], {type:type }); } /** * 上傳 */ function upload(){ //base64 轉 blob var $Blob= getBlobBydataURI(document.getElementsByTagName("img")[0].currentSrc,'image/jpeg'); var formData = new FormData(); formData.append("files", $Blob ,"file_"+Date.parse(new Date())+".jpeg"); //組建XMLHttpRequest 上傳檔案 var request = new XMLHttpRequest(); //上傳連線地址 request.open("POST", "www.xxx.com"); request.onreadystatechange=function() { if (request.readyState==4) { if(request.status==200){ console.log("上傳成功"); }else{ console.log("上傳失敗,檢查上傳地址是否正確"); } } } request.send(formData); } </script> </head> <body> <button onclick="upload()">上傳測試</button> <br /> 上傳的圖片: <img src="data:image/jpeg;base64,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" /> </body> </html>
備註：
WindowOrWorkerGlobalScope.atob() 對用base-64編碼過的字串進行解碼 。你可以使用 window.btoa() 方法來編碼一個可能在傳輸過程中出現問題的資料，並且在接受資料之後，使用 atob() 方法再將資料解碼。例如：你可以編碼、傳輸和解碼操作各種字元，比如0-31的ASCII碼值。
let encodedData = window.btoa("Hello, world"); // 編碼
let decodedData = window.atob(encodedData); // 解碼
來源於：
https://www.jb51.net/article/105513.htm
https://developer.mozilla.org/zh-CN/docs/Web/API/WindowBase64/atob