<!doctype html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <script type="text/javascript"> function showPreview(source) { var file = source.files[0]; if(!/image/w+/.test(file.type)){ alert("请确保文件为图像类型"); return false; } if(window.FileReader) { var fr = new FileReader(); fr.onloadend = function(e) { document.getElementById("portrait").src = e.target.result; }; fr.readAsDataURL(file); } } window.onload=function () { var h = { init: function() { var me = this; document.getElementById('File').onchange = me.fileHandler; document.getElementById('Abort').onclick = me.abortHandler; me.status = document.getElementById('Status'); me.progress = document.getElementById('Progress'); me.percent = document.getElementById('Percent'); me.loaded = 0; //每次读取1M me.step = 1024 * 1024; me.times = 0; }, fileHandler: function(e) { var me = h; var file = me.file = this.files[0]; var reader = me.reader = new FileReader(); // me.total = file.size; reader.onloadstart = me.onLoadStart; reader.onprogress = me.onProgress; reader.onabort = me.onAbort; reader.onerror = me.onerror; reader.onload = me.onLoad; reader.onloadend = me.onLoadEnd; //读取第一块 me.readBlob(file, 0); }, onLoadStart: function() { var me = h; }, onProgress: function(e) { var me = h; me.loaded += e.loaded; //更新进度条 me.progress.value = (me.loaded / me.total) * 100; }, onAbort: function() { var me = h; }, onError: function() { var me = h; }, onLoad: function() { var me = h; if(me.loaded < me.total) { me.readBlob(me.loaded); } else { me.loaded = me.total; } }, onLoadEnd: function() { var me = h; }, readBlob: function(start) { var me = h; var blob, file = me.file; me.times += 1; if(file.webkitSlice) { blob = file.webkitSlice(start, start + me.step + 1); } else if(file.mozSlice) { blob = file.mozSlice(start, start + me.step + 1); }else if(file.slice) { blob = file.slice(start, start + me.step + 1); } me.reader.readAsText(blob); }, abortHandler: function() { var me = h; if(me.reader) { me.reader.abort(); } } }; h.init(); } </script> <input type="file" name="file" onchange="showPreview(this)" /> <img id="portrait" src="" width="70" height="75"> <form> <fieldset> <legend>分度读取文件：</legend> <input type="file" id="File" /> <input type="button" value="中断" id="Abort" /> <p> <label>读取进度：</label><progress id="Progress" value="0" max="100"></progress> </p> <p id="Status"></p> </fieldset> </form> </body> </html>