原生javascript实现文件异步上传

效果图：
代码：（demo33.jsp）
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>demo33.jsp</title>
</head>
<body>
<label for="text">名称</label>
<input type="text" id="text" name="name"/>
<label for="file">文件</label>
<input type="file" id="file" name="file"/>
<button type="button" onclick="ajaxUploadFile()">确定</button>
</body>
<script type="text/javascript">
    function ajaxUploadFile() {
        var formData = new FormData();
        var xmlhttp;
        if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari
            xmlhttp = new XMLHttpRequest();
        }else {// code for IE6, IE5
            xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
        }
        xmlhttp.open("POST","/data",true);
        xmlhttp.setRequestHeader("X-Requested-With", "XMLHttpRequest");
        formData.append("name",document.getElementById("text").value);
        formData.append("file",document.getElementById("file").files[0]);
        xmlhttp.send(formData);
        xmlhttp.onreadystatechange=function() {
            if (xmlhttp.readyState==4) {
                if (xmlhttp.status==200) {
                    console.log("上传成功"+xmlhttp.responseText);
                }else {
                    console.log("上传失败"+xmlhttp.responseText);
                }
            }
        }
    }
</script>
</html>