Spring Roo,Apache Tiles显示在控制器中设置的模型属性

我正在使用Spring roo,并且在其中一个控制器中,我使用如下字符串设置了模型属性“ error”：

//uiModel.addAttribute("error","Duplicate name for Vendor");

@RequestMapping(method = RequestMethod.POST)
public String create(@Valid Vendor vendor,BindingResult bindingResult,Model uiModel,HttpServletRequest httpServletRequest) {
    if (bindingResult.hasErrors()) {
        uiModel.addAttribute("vendor",vendor);
        addDateTimeFormatPatterns(uiModel);
        return "vendors/create";
    }

    try {
        vendorService.saveVendor(vendor);
        uiModel.asMap().clear();
    } catch(Exception e) {
        uiModel.addAttribute("vendor",vendor);
        uiModel.addAttribute("error","Duplicate name for Vendor");
        addDateTimeFormatPatterns(uiModel);
        return "vendors/create";
    }
    return "redirect:/vendors/" + encodeUrlPathSegment(vendor.getId().toString(),httpServletRequest);
}

现在,我的问题是如何在创建页面上显示错误(如果不为null),如下所示.

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<div xmlns:c="http://java.sun.com/jsp/jstl/core" xmlns:field="urn:jsptagdir:/WEB-INF/tags/form/fields" xmlns:form="urn:jsptagdir:/WEB-INF/tags/form" xmlns:jsp="http://java.sun.com/JSP/Page" xmlns:spring="http://www.springframework.org/tags" version="2.0">
    <jsp:directive.page contentType="text/html;charset=UTF-8"/>
    <jsp:output omit-xml-declaration="yes"/>
    <form:create id="fc_domain_Vendor" modelAttribute="vendor" path="/vendors" render="${empty dependencies}" z="MGZPL+gO+CDX6M4iRO/z/qRfnJI=">
        <field:input field="name" id="c_domain_Vendor_name" required="true" z="s+3hs8xXpSZ71RoD0ktXy0BnjS0="/>
        <field:input field="email" id="c_domain_Vendor_email" validationMessageCode="field_invalid_email" z="+4rIdPGArWhHQlrFG/1N6yrKKno="/>
        <field:input field="mobile" id="c_domain_Vendor_mobile" max="16" z="kgM5Z9jJ6xW9BxiPPB4Ipz0TUKg="/>
    </form:create>
    <form:dependency dependencies="${dependencies}" id="d_domain_Vendor" render="${not empty dependencies}" z="hLv7c7K8OOSRrBJKgKuw9H1+GvA="/>
</div>

提前致谢