poi3.7 读取excel2007 问题

private void test(String strPath) throws IOException{
XSSFWorkbook xwb;
xwb = new XSSFWorkbook(strPath);
XSSFSheet sheet = xwb.getSheetAt(0); 
// 读取第一章表格内�?
// 定义 row、cell 
XSSFRow row; 
String cell; 
// 循环输出表格中的内容 
for (int i = sheet.getFirstRowNum(); i < sheet.getPhysicalNumberOfRows(); i++ ) { 
row = sheet.getRow(i); 
for (int j = row.getFirstCellNum(); j < row.getPhysicalNumberOfCells(); j++ ) { 
// 通过 row.getCell(j).toString() 获取单元格内容， 
cell = row.getCell(j)!=null?row.getCell(j).toString():""; 
System.out.print(cell+"\t"); 
} 
System.out.println("");
} 
}各位大侠 我用main() 方法直接调用上段方法可以读取excel2007 ，但当我将上段代码放入web工程中 tomcat 中就报错：
org.apache.poi.POIXMLException: java.lang.reflect.InvocationTargetException
at org.apache.poi.xssf.usermodel.XSSFFactory.createDocumentPart(XSSFFactory.java:61)
at org.apache.poi.POIXMLDocumentPart.read(POIXMLDocumentPart.java:277)
at org.apache.poi.POIXMLDocument.load(POIXMLDocument.java:186)
at org.apache.poi.xssf.usermodel.XSSFWorkbook.<init>(XSSFWorkbook.java:182)
at org.apache.poi.xssf.usermodel.XSSFWorkbook.<init>(XSSFWorkbook.java:198)
at com.qeweb.sop.purchase.util.ImportTaskUtil2.readForecastDataFromExcel(ImportTaskUtil2.java:190)
at com.qeweb.fleetguard.purchase.web.MaterialForecastImportExportAction.importFromExcel(MaterialForecastImportExportAction.java:159)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:269)
at org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:170)
at com.qeweb.core.web.BaseActionInternal.execute(BaseActionInternal.java:87)
at org.apache.struts.chain.commands.servlet.ExecuteAction.execute(ExecuteAction.java:58)
at org.apache.struts.chain.commands.AbstractExecuteAction.execute(AbstractExecuteAction.java:67)
at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:304)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.qeweb.core.filter.AbstractLoginFilter.doFilter(AbstractLoginFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.qeweb.core.filter.EncodingFilter.doFilter(EncodingFilter.java:77)
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:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:857)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:565)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1509)到底是什么原因，请各位大侠指教！