时间：2021-07-01 10:21:17 帮助过：4人阅读
<!doctype html >
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<title>html5 file and filereader</title>
<link href="html/ui.css" _mce_href="html/ui.css" rel="stylesheet" />
</head>
<body>
<style type="text/css"><!--
.box{background:#f8f8f8;border:1px solid #ccc;padding:10px;-webkit-box-shadow:#000 0px 0px 4px;-moz-box-shadow:#000 0px 0px 4px;
-webkit-border-radius:2px;font-family: 'segoe ui', calibri, 'myriad pro', myriad, 'trebuchet ms', helvetica, arial, sans-serif;
}
.bl{ font-weight:700;}
.dl{ padding:10px; border-top:1px dotted #999;}
.dl dd{ padding:0; margin:0;}
.log{border:1px solid #ccc; background:#f8f8f8; width:200px; position:absolute; right:10px; top:10px;}
.log li{border:1p dotted #ccc;word-wrap:break-word;word-break:break-all; margin:0px; padding:0;}
.log ul{margin:0px; padding:0; list-style:none;}
--></style><style type="text/css" _mce_bogus="1"><!--
.box{background:#f8f8f8;border:1px solid #ccc;padding:10px;-webkit-box-shadow:#000 0px 0px 4px;-moz-box-shadow:#000 0px 0px 4px;
-webkit-border-radius:2px;font-family: 'segoe ui', calibri, 'myriad pro', myriad, 'trebuchet ms', helvetica, arial, sans-serif;
}
.bl{ font-weight:700;}
.dl{ padding:10px; border-top:1px dotted #999;}
.dl dd{ padding:0; margin:0;}
.log{border:1px solid #ccc; background:#f8f8f8; width:200px; position:absolute; right:10px; top:10px;}
.log li{border:1p dotted #ccc;word-wrap:break-word;word-break:break-all; margin:0px; padding:0;}
.log ul{margin:0px; padding:0; list-style:none;}
--></style>
<div class="box" id="baseinfo">
<h2>（把图片拖拽到这里）利用 filereader 获取文件 base64 编码</h2>
<div></div>
</div>
<div class="log">
<ul id="log">
</ul>
</div>
<script type="text/CSS" ><!--
(function(){
window.datavalue = 0;
var html = ' <dl class="dl">
<dd>filename: $filename$</dd>
<dd>filetype: $filetype$</dd>
<dd>filesize: $filesize$</dd>
<dd><img src="$data$" /></dd>
<dd>filebase64: <br/>
<div style="width:100%; height:100px;">$filebase64$</div>
</dd>
</dl>
'
var log = function(msg){
//console['log'](msg);
document.getelementbyid('log').innerhtml += '<li>'+ msg +'</li>';
}
var dp = function(){
var defconfig = {
dropwrap : window
}
this.init.apply(this, [defconfig]);
this.file = null;
}
dp.prototype = {
init:function(args){
var dropwrap = args.dropwrap;
var _this = this;
dropwrap.addeventlistener("dragenter", this._dragenter, false);
dropwrap.addeventlistener("dragover", this._dragover, false);
dropwrap.addeventlistener('drop', function(e){_this.readfile.call(_this,e)} , false);
log('window drop bind--ok');
},
_dragenter:function(e){e.stoppropagation();e.preventdefault();},
_dragover:function(e){e.stoppropagation();e.preventdefault();},
readfile:function(e){
e.stoppropagation();
e.preventdefault();
var dt = e.datatransfer;
var files = dt.files;
for(var i = 0; i< files.length;i++){
var html = html.slice();
html = this.writeheader(files[i], html);
this.read(files[i], html);
}
},
read:function(file, h){
var type = file.type;
var reader = new filereader();
reader.onprogress = function(e){
if (e.lengthcomputable){
log('progress: ' + math.ceil(100*e.loaded/file.size) +'%')
}
};
reader.onloadstart = function(e){
log('onloadstart: ok');
};
reader.onloadend = function(e){
var _result = e.target.result;
//console['log'](e.target);
log('data uri--ok');
var d = document.createelement('div');
h = h.replace('$filebase64$', _result);
if(/image/.test(file.type)){
h = h.replace('$data$',_result);
}
d.innerhtml = h;
document.getelementbyid('baseinfo').appendchild(d);
};
reader.readasdataurl(file); // www.3ppt.com base 64 编码
return;
},
writeheader:function(file, h){
log(file.filename + '+' + (file.size/1024));
return h.replace('$filename$', file.filename).replace("$filesize$",(file.size/1024)+'kb').replace("$filetype$",file.type);
}
}
new dp();
})()
// --></script>
</body>
</html>
filereader对象
var filereader = new filereader();
filereader.onloadend = function(){
console.log(this.readystate); // 这个时候 应该是 2
console.log(this.result); 读取完成回调函数，数据保存在result中
}
filereader.readasbinarystring(file);// 开始读取2进制数据 异步 参数为file 对象
//filereader.readasdataurl(file); // 读取base64
//filereader.readastext(file);//读取文本信息