<!DOCTYPE html >
<html >
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>图片上传本地预览，获得图片的base64(可压缩)</title>
<style type="text/css">
.upload_image {
width: 800px;
}
</style>
<script type="text/javascript" src="jquery.min.js"></script>
</head>
<body>
<div id="preview">
<img id="imghead" width=200 height=200 border=0 src=''>
</div>
<canvas id="uploadImg" hidden></canvas>
<input type="file" id="fileUp" multiple hidden />
<label for="fileUp">点击上传图片</label>
<button id='sub'>提交</button>
<script type="text/javascript">
var imgUpload = {
imgBase64Arr: [],
html : '',
onSelect: function(files) {
var i =0;
$("#preview").html('<div class="upload_loading"></div>');
var funAppendImage = function() {
file = files.files[i];
if (file) {
var reader = new FileReader()
reader.onload = function(e) {
imgUpload.html = imgUpload.html + '<div id="uploadList_' + i + '" class="upload_append_list"><p class="img-outbox"><strong>' + file.name + '</strong>' +
'<a href="javascript:" class="upload_delete" title="删除" data-index="' + i + '">删除</a><br />' +
'<img id="uploadImage_' + i + '" src="' + e.target.result + '" class="upload_image" /></p>' +
'<span id="uploadProgress_' + i + '" class="upload_progress"></span>' +
'</div>';
i++;
funAppendImage();
}
reader.readAsDataURL(file);
} else {
$("#preview").html(imgUpload.html);
$(".upload_delete").click(function(){
imgUpload.funDelteimg($(this).parents(".img-outbox"));
// console.log(files.files[parseInt($(this).attr("data-index"))])
// imgUpload.funDelteimg(files.files[parseInt($(this).attr("data-index"))]);
}
)
}
};
funAppendImage();
},
funDelteimg: function(_this){
console.log(_this)
$(_this).remove();//只能删除dom，无法删除内存中的files.files
},
funCanvas : function(width, height, ratio, file){//重新绘制图片，获得img的base64
var canvas = document.getElementById("uploadImg");
var cxt = canvas.getContext('2d');
canvas.width = width;
canvas.height = height;
var img = new Image();
img.src = file;
cxt.drawImage(img, 0, 0, width, height);
var imgBase = canvas.toDataURL("image/jpeg", ratio);
imgUpload.imgBase64Arr.push(imgBase);
return imgUpload.imgBase64Arr;
},
}
//文件上传
$("#fileUp").change(function(){
imgUpload.onSelect(this)
})
//获得所有img的 src,可以传给后端
$("#sub").click(function(){
var getBase = $(".upload_image");
getBase.each(function(){//重新绘制图片，减小base64字符串的长度
imgUpload.funCanvas(640, 400, 0.6, $(this).attr("src"));
})
console.log(imgUpload.imgBase64Arr)
})
</script>
</body>
</html>
这里图片上传的思路：获得上传后的img,将file的img 转成base64 ,作为前端预览，也可以将base64的字符串，传到后端，由后端生成图片，在传到后端前，可以将其base64的字符串压缩一下，这里的采取的一个方法就是用canvas的重新绘制图片，然后在canvas里就会有 新的base64字符串。
