那是我的servlet代码
@WebServlet(name = "pdf", urlPatterns = {"/pdf"})
公共类pdf扩展了HttpServlet { 受保护的void doGet（HttpServletRequest请求，HttpServletResponse响应） 引发ServletException，IOException {
Connection con = DBConexion.IniciarSesion();
System.out.print("---conexion DB----");
ServletOutputStream servletOutputStream =response.getOutputStream();
InputStream reportStream =getServletConfig().getServletContext().getResourceAsStream("/reportesj/reportsinparametro.jasper");
HashMap parameterMap = new HashMap();
String stdID="510BCT2010";
String semester="1";
parameterMap.put("stdID", stdID);
parameterMap.put("semester", semester);
try
{
JasperRunManager.runReportToPdfStream(reportStream,servletOutputStream, parameterMap, con);
con.close();
response.setContentType("application/pdf");
servletOutputStream.flush();
servletOutputStream.close();
}
catch (Exception e)
{
// display stack trace in the browser
StringWriter stringWriter = new StringWriter();
PrintWriter printWriter = new PrintWriter(stringWriter);
e.printStackTrace(printWriter);
response.setContentType("text/plain");
response.getOutputStream().print(stringWriter.toString());
}
}
/**
* Handles the HTTP <code>POST</code> method.
*
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
}
错误日志
java.lang.NullPointerException
at java.io.ObjectInputStream$PeekInputStream.read(ObjectInputStream.java:2620)
at java.io.ObjectInputStream$PeekInputStream.readFully(ObjectInputStream.java:2636)
at java.io.ObjectInputStream$BlockDataInputStream.readShort(ObjectInputStream.java:3113)
at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:853)
at java.io.ObjectInputStream.<init>(ObjectInputStream.java:349)
at net.sf.jasperreports.engine.util.ContextClassLoaderObjectInputStream.<init>(ContextClassLoaderObjectInputStream.java:58)
at net.sf.jasperreports.engine.util.JRLoader.loadObject(JRLoader.java:249)
at net.sf.jasperreports.engine.util.JRLoader.loadObject(JRLoader.java:234)
at net.sf.jasperreports.engine.JasperFillManager.fill(JasperFillManager.java:416)
at net.sf.jasperreports.engine.JasperRunManager.runToPdfStream(JasperRunManager.java:210)
at net.sf.jasperreports.engine.JasperRunManager.runReportToPdfStream(JasperRunManager.java:729)
at reporte.pdf.doGet(pdf.java:83)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:217)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)