pomxml：commons-fileupload，commons-io

<form action="./scholastic/downImage" method="post" enctype="multipart/form-data" >

<img src="" width="300" heigth="300" id="picimg">

<input type="file" name="downfile" onchange="showPic(this);">

<button type="submit" class="layui-btn">下载图片</button>

</form>

<script type="text/javascript">

function showPic(obj) {

var newPreview = document.getElementById('picimg');

if (obj) {

//ie浏览器兼容

if (window.navigator.userAgent.indexOf("MSIE") >= 1) {

obj.select();

newPreview.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale);";

var path = document.selection.createRange().text;

var flag = judgeImgSuffix(path);

if(flag){

newPreview.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = document.selection.createRange().text;

}else{

console.log("要求图片格式为png,jpg,jpeg");

}

return;

}

//firefox浏览器兼容

else if (window.navigator.userAgent.indexOf("Firefox") >= 1) {

if (obj.files) {

newPreview.src = window.URL.createObjectURL(obj.files.item(0));

return;

}

newPreview.src = obj.value;

return;

}

newPreview.src = obj.value;

return;

}

}

function judgeImgSuffix(path){

var index = path.lastIndexOf('.');

var suffix = "";

if(index > 0){

suffix = path.substring(index+1);

}

if("png"==suffix || "jpg"==suffix || "jpeg"==suffix || "PNG"==suffix || "JPG"==suffix || "JPEG"==suffix){

return true;

}else{

console.log("图片格式不正确");

return false;

}

}

</script>