已经导入struts2-dojo-plugin-2.3.24.1.jar，jsp页面如下：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%@ taglib prefix="s" uri="/struts-tags" %>
<%@ taglib prefix="sx" uri="/struts-dojo-tags" %>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>登录页面</title>
<sx:head />
</head>
<body>
<s:form action="Login" theme="ajax">
<table width="60%" height="76" border="0">
<s:textfield name="username" label="用户名" />
<s:password name="password" label="密码" />
<s:submit value="登录" align="center" />
</table>
</s:form>
</body>
报运行时以下错误：
FreeMarker template error (HTML_DEBUG mode; use RETHROW in production!)
The following has evaluated to null or missing:
==> parameters.pushId [in template "template/ajax/submit.ftl" at line 103, column 6]
Tip: It's the step after the last dot that caused this error, not those before it.
Tip: If the failing expression is known to be legally refer to something that's null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??
FTL stack trace ("~" means nesting-related):
- Failed at: #if parameters.pushId [in template "template/ajax/submit.ftl" at line 103, column 1]
Java stack trace (for programmers):
freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...]
at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:116)
at freemarker.core.UnexpectedTypeException.newDesciptionBuilder(UnexpectedTypeException.java:60)
at freemarker.core.UnexpectedTypeException.(UnexpectedTypeException.java:40)
at freemarker.core.NonBooleanException.(NonBooleanException.java:44)
。。。
