Java Liferay：如何制作enctype="；“多部分/表单数据”；方法=”；邮政「；一起工作？

我正在使用liferay portal server 6.2开发一个web应用程序

JSP代码-

    <form id="mainForm" action="<portlet:actionURL/>" method="post" enctype="multipart/form-data" >
<input type="hidden" id="varImport" name="varImport"/>
    <div class="tab-pane" id="uploadFile">
        <p>Please upload a file</p>
        <div id="inputFileDiv">
            <input type="file" name="uploadFile" />
        </div>
    </div>
    <input type="submit" class="btn btn-info" onClick="import()" value="IMPORT" />
    </form>

    <script>
        function import() {
            console.log("importing");
            document.getElementById("varImport").value = "IMPORTFILE";
            document.getElementById("mainForm").submit();
        }
    </script>

如果我从jsp表单中删除enctype，我将在servlet中获得varImport的值

但如果我保留它，它将返回null

我错过了什么

检查此链接

import com.liferay.portal.util.PortalUtil;
UploadPortletRequest uploadRequest = PortalUtil.getUploadPortletRequest(request);
System.out.println("myPortlet.processAction() >> " + uploadRequest.getParameter("varImport"));

import com.liferay.portal.util.PortalUtil;
UploadPortletRequest uploadRequest = PortalUtil.getUploadPortletRequest(request);
System.out.println("myPortlet.processAction() >> " + uploadRequest.getParameter("varImport"));