struts上传文件问题

[一生皆是为填坑]

求助,struts上传文件,在Action中获取不到文件相关的参数
jsp中代码:
<s:form action ="importExc" method ="POST" enctype ="multipart/form-data" namespace="/upload" >
<s:file name ="myFile" label ="Image File" />
<s:submit/>
</s:form>


struts2的xml配置:

<?xml version="1.0" encoding="GBK"?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd">

<struts>
<package name="Struts2" extends="struts-default" namespace="/upload">
<action name="importExc" class="com.doone.ecp.sys.spm.action.urge.UploadAction">
<!-- 指定（限制）上传文件的类型，定义局部拦截器，修改默认拦截器的属性
"fileUpload.maximumSize" ：限制上传最大的文件大小。
"fileUpload.allowedTypes"：允许上传文件的类型。
"fileUpload.allowedExtensions"：允许上传文件的可扩展文件类型。
<interceptor-ref name="defaultStack">
<param name="fileUpload.maximumSize">500000000</param>
<param name="fileUpload.allowedTypes">text/plain,application/vnd.ms-excel</param>
<param name="fileUpload.allowedExtensions">.txt,.xlsx</param>
</interceptor-ref> -->
<!-- <interceptor-ref name ="fileUploadStack"/> -->
<result name="success">/ecp3.0/pages/sys/black/upExc.jsp</result>
</action>
</package>
</struts>


Action代码:
public class UploadAction extends ActionSupport{
private static final long serialVersionUID = 1L;
private File myFile;

private String myFileContentType;

public File getMyFile() {
return myFile;
}

public void setMyFile(File myFile) {
this.myFile = myFile;
}

public String getMyFileContentType() {
return myFileContentType;
}

public void setMyFileContentType(String myFileContentType) {
this.myFileContentType = myFileContentType;
}
@Override
public String execute() throws Exception {
System.out.println(myFile);
return NONE;
}
}

我用idea重搭了个环境,用同样的代码就可以,但在现在这个项目里面就是不行,求指点导