1.jQuery和Ajax异步上传:
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2019/7/22
Time: 17:18
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>$Title$</title>
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery-2.1.0.js"></script>
</head>
<body>
<form id="fm" action="/xx" method="post" enctype="application/x-www-form-urlencoded">
<input id="n" name="name" value="formname">
<input id="f" name="xx" value="formname">
<%-- 预览 用户看的--%>
<img id="img" width="100px" />
<input id="hd" type="hidden" name="path">
<input id="fl" type="file" name="fl" >
<input type="button" value="按钮" id="bt">
</form>
<script>
$("#fl").change(function () {
var formdata =