struts2文件上载发生java.lang.IllegalStateException

<action name="downLoadAccountCheck" class="downLoadAccountCheckAction">
<result name="errorpage">./downerror.jsp</result>
<result name="success" type="stream">
<param name="contentType">
application/octet-stream;charset=ISO8859-1
</param>
<param name="inputName">inputStream</param>
<!-- 使用经过转码的文件名作为下载文件名，downloadFileName属性对应action类中的方法 getDownloadFileName() -->
<param name="contentDisposition">
attachment;filename="${downloadFileName}"
</param>
<param name="bufferSize">4096</param>
</result>
</action>

public String spInfo() {
System.out.println("到达了spInfo1111111111"+spName);
try {
// 获取当前登录帐号
String operatorId =ActionUtil.getLoginUserID();
System.out.println("operatorId="+operatorId);
//权限当前取和按sp查询交易记录报表一致
int right = AuthorityUtil.getTopRight(operatorId, "ID_RETRANS_STATBYSP_REPORT");

String district=null;
if(right == AuthorityUtil.LOCAL_DATA_VISIBLE){
String local=ActionUtil.getLocalID(operatorId);
if(local==null||local.equals("")){
this.message = "查询成功！";
success = true;
return SUCCESS;
}

//如果登录用户不是省公司用户或维护人员，需要进行地域限制
if(!local.equals("ALL")&&!local.equals("DW")){
district = local;
}

}
if(right == AuthorityUtil.INVISIBLE){
this.message = "查询成功！";
success = true;
return SUCCESS;
}

list = reTxnLogDAO.queryTradeSp(spName, spState,district, startDate, endDate);
File file=new File(getFileNameForSPinfo(spName, spState, startDate, endDate)+".xls");
//File file=new File("d:/sptemp.xls");
if(file.exists()){
file.delete();
}
file.createNewFile();
System.out.println("file----abs:"+file.getAbsolutePath());
createSPInfoExcel(file, list);
downloadExcel(file, ServletActionContext.getResponse());
delExcel(file);
//message = "查询成功！";
//success = true;
} catch (Exception e) {
message = "查询失败！";
success = false;
e.printStackTrace();
}
return SUCCESS;
}

严重: Servlet.service() for servlet default threw exception
java.lang.IllegalStateException
at org.apache.catalina.connector.ResponseFacade.sendError(ResponseFacade.java:407)
at org.apache.struts2.dispatcher.Dispatcher.sendError(Dispatcher.java:742)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:513)
at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:422)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:261)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:581)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Unknown Source)