基于HTML5 Ajax實現(xiàn)文件上傳并顯示進度條

var file = null; 
var input = $("#file_upload"); 
//文件域選擇文件時, 執(zhí)行readFile函數(shù) 
input.addEventListener('change',readFile,false); 
function readFile(){ 
 file = this.files[0]; 
} 

 var fd = new FormData(); 
fd.append("file", file); 

 
//監(jiān)聽事件 
hr.upload.addEventListener("progress", uploadProgress, false); 

html> 
head> 
meta charset="utf-8"> 
title>進度條測試/title> 
script type="text/javascript" src="../js/jquery-1.11.1.min.js">/script> 
/head> 
body> 
 
 input type="file" id="file_upload"/> 
 input type="button" value="上傳" id="upload"/> 
 div style="background:#848484;width:100px;height:10px;margin-top:5px"> 
 div id="progressNumber" style="background:#428bca;width:0px;height:10px" > 
 /div> 
 /div> 
 font id="percent">0%/font> 
/body> 
script> 
var file = null; 
$(function(){ 
 $("#upload").click(function(){ 
 upload(); 
 }); 
}); 
var input = document.getElementById("file_upload"); 
 
//文件域選擇文件時, 執(zhí)行readFile函數(shù) 
input.addEventListener('change',readFile,false); 
 
function readFile(){ 
 file = this.files[0]; 
} 
//上傳文件 
function upload(){ 
 var xhr = new XMLHttpRequest(); 
 
 var fd = new FormData(); 
 
 fd.append("fileName", file); 
 
 //監(jiān)聽事件 
 xhr.upload.addEventListener("progress", uploadProgress, false); 
 
 //發(fā)送文件和表單自定義參數(shù) 
 xhr.open("POST", "../UploadServlet",true); 
 
 xhr.send(fd); 
 } 
 
 function uploadProgress(evt){ 
 if (evt.lengthComputable) {   
  //evt.loaded：文件上傳的大小 evt.total：文件總的大小   
  var percentComplete = Math.round((evt.loaded) * 100 / evt.total); 
  //加載進度條，同時顯示信息  
  $("#percent").html(percentComplete + '%') 
  $("#progressNumber").css("width",""+percentComplete+"px");  
 } 
 } 
/script> 
/html>