方法一:canvas
<script type="text/javascript">
function getBase64Image(img) {
var canvas = document.createElement("canvas");
canvas.width = img.width;
canvas.height = img.height;
var ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0, img.width, img.height);
var dataURL = canvas.toDataURL("image/png");
return dataURL
}
function main() {
var img = document.createElement('img');
img.src = './images/Game of Thrones.jpg'; //此处自己替换本地图片的地址
img.onload =function() {
var data = getBase64Image(img);
var img1 = document.createElement('img');
img1.src = data;
document.body.appendChild(img1);
console.log(data);
}
}
main()
</script>
方法二:FileReader
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>通过filereader接口读取文件</title>
<script type="text/javascript">
function readAsDataURL()
{
if(typeof FileReader=='undifined') //判断浏览器是否支持filereader
{
result.innerHTML="<p>抱歉，你的浏览器不支持 FileReader</p>";
return false;
}
var file=document.getElementById("imagefile").files[0];
if(!/image\/\w+/.test(file.type)) //判断获取的是否为图片文件
{
alert("请确保文件为图像文件");
return false;
}
var reader=new FileReader();
reader.readAsDataURL(file);
reader.onload=function(e)
{
var result=document.getElementById("result");
result.innerHTML='<img src="'+this.result+'" alt=""/>'
}
}
</script>
</head>
<body>
<p>
<label>请选择一个文件：</label>
<input type="file" id="imagefile" />
<input type="button" value="读取图像" onClick="readAsDataURL();" />
</p>
<div name="result" id="result">
<!-- 这里用来显示图片结果-->
</div>
</body>
</html>
案例：
html
<div class="layui-upload-list" style="float: left;"> <img class="layui-upload-img" id="test-upload-normal-img-bannerImg03"/> <p id="test-upload-demoText3" style="margin: -38px 0 0 215px"></p> </div> <input type="file" name="bannerImg03" id="bannerImg03" onchange="show(this,this.id)" style="margin: 172px 0 0 10px;">
js
function show(element,id) {
var rd = new FileReader();//创建文件读取对象
var files = element.files[0];//获取file组件中的文件
rd.readAsDataURL(files);//文件读取装换为base64类型
rd.onloadend = function (e) {
//加载完毕之后获取结果赋值给img
document.getElementById("test-upload-normal-img-"+id).src =this.result;
document.getElementById("test-upload-normal-img-"+id).style.width = 200+"px";
document.getElementById("test-upload-normal-img-"+id).style.height = 200+"px";
}
}}
if (document.getElementById("iconImg").files[0] == undefined) { layer.msg('商品缩略图'); return false; } else { document.getElementById("test-upload-normal-img-iconImg").src.toString() }
base编码比较长 后台用StringBuilder 接受 @RequestParam(value = "iconImg") StringBuilder iconImg