web jasperreport问题

doPost请求里处理如下:
try {

//InputStream is = new FileInputStream("D:/PROJECT_TEMP/MYWS/JasperReportPrj/report/myReport.jasper");
InputStream input = new FileInputStream(new File("D:/PROJECT_TEMP/MYWS/JasperReportPrj/report/myReport.jasper"));
JasperReport jasperReport = (JasperReport) JRLoader.loadObject(input);
CustomDataSource cds = new CustomDataSource();//自己封装的 javaBean 对象
HashMap<String, Object> parameters = new HashMap<String, Object>();
byte[] bytes = JasperRunManager.runReportToPdf(jasperReport,parameters, cds);
System.out.println("size");
response.setContentType("application/pdf");
response.setContentLength(bytes.length);
ServletOutputStream ouputStream = response.getOutputStream();
ouputStream.write(bytes, 0, bytes.length);
ouputStream.flush();
ouputStream.close();


} catch (Exception ex) {
ex.printStackTrace();
}  为什么一直报错:
2008-12-8 14:39:16 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet openPdf threw exception
java.lang.NoClassDefFoundError
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at net.sf.jasperreports.engine.JasperCompileManager.getCompiler(JasperCompileManager.java:476)
at net.sf.jasperreports.engine.JasperCompileManager.loadEvaluator(JasperCompileManager.java:242)
at net.sf.jasperreports.engine.fill.JRFillDataset.createCalculator(JRFillDataset.java:411)
at net.sf.jasperreports.engine.fill.JRBaseFiller.<init>(JRBaseFiller.java:404)
at net.sf.jasperreports.engine.fill.JRVerticalFiller.<init>(JRVerticalFiller.java:77)
at net.sf.jasperreports.engine.fill.JRVerticalFiller.<init>(JRVerticalFiller.java:59)
at net.sf.jasperreports.engine.fill.JRFiller.createFiller(JRFiller.java:147)
at net.sf.jasperreports.engine.fill.JRFiller.fillReport(JRFiller.java:83)
at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager.java:601)
at net.sf.jasperreports.engine.JasperRunManager.runReportToPdf(JasperRunManager.java:419)
at openPdf.doPost(openPdf.java:31)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:174)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
at java.lang.Thread.run(Unknown Source) 我在网上查询的是,由于commons-collections-3.2.jar 包的版本问题,但是我都尝试过了. 还是一直报错.请高手指点指点...