4:23 a.m.
All,
my question may looks strange,
I tried to get a common java servlet work within a seam application by adding the
following line in web.xml: (calculator is the servlet name)
<servlet>
| <servlet-name>Calculator</servlet-name>
| <servlet-class>server.Calculator</servlet-class>
| </servlet>
|
| <servlet-mapping>
| <servlet-name>Calculator</servlet-name>
| <url-pattern>/Calculator</url-pattern>
| </servlet-mapping>
the servlet worked fine (I called it from a mobile phone, that's why I need a servlet)
after I deployed the seam app with this servlet. but when I tried to use the seam app
itself by browser (the hotel booking example), it just didn't work. seems there are
conflicts between the new lines I added and the old lines in web.xml .
then I changed the servlet by adding ejb3 annotation (it's strange, huh? a ejb3
staless session bean servlet) and re-deploy the app again (with the new lines in the
web.xml). then the servlet (also a session bean) worked well and the hotel booking example
worked fine as normal.
then added persistency statement to this servlet (the session bean) but I got a NPE, which
seems the Entity manager is null and I can't get the entity manager properly in a
servlet which is also a ejb3 session bean?
the code is like this:
package server;
|
| import javax.ejb.Stateless;
| import javax.servlet.*;
| import javax.servlet.http.*;
| import java.io.*;
| import java.text.*;
| import javax.persistence.EntityManager;
| import javax.persistence.PersistenceContext;
|
|
| @Stateless
| public class Calculator extends HttpServlet implements cacu
| {
| @PersistenceContext
| private EntityManager em;
| private Reguser user;
|
| public void doPost(HttpServletRequest request,HttpServletResponse response)
| throws IOException, ServletException
| {
| response.setContentType("text/plain");
| PrintWriter out = response.getWriter();
| String uid = request.getParameter("uid");
| String passwd =request.getParameter("passwd");
| user = em.find(Reguser.class, "rency"); (exception here, em is null)
| String email = user.getEmail();
| System.out.print(email);
| out.println("just a test: "+ uid);
| }
|
| }
exception was:
10:16:49,501 ERROR [[Calculator]] Servlet.service() for servlet Calculator threw
exception
| java.lang.NullPointerException
| at server.Calculator.doPost(Calculator.java:26) (the entity manager) at
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
| at javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
| at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
| at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
| at
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
| at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
| at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
| at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
| at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
| at
org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:175)
| at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:74)
| at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
| at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
| at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
| at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
| at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
| at
org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
| at
org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
| at
org.apache.tomcat.util.net.MasterSlaveWorkerThread.run(MasterSlaveWorkerThread.java:112)
| at java.lang.Thread.run(Thread.java:595)
also I added a ejb3 web service in the app, the web service work well: code like this:
interface:
package server;
|
| import javax.jws.WebService;
| import javax.jws.WebMethod;
|
|
| @WebService
| public interface findEmail {
|
| @WebMethod public String findemail(String username);
|
| }
the implementation:
package server;
|
| import javax.ejb.Stateless;
| import javax.jws.WebService;
| import javax.persistence.EntityManager;
| import javax.persistence.PersistenceContext;
|
|
| @Stateless
| @WebService(endpointInterface="server.findEmail")
|
| public class findemailimpl implements findemail {
|
| @PersistenceContext
| private EntityManager em;
| private Reguser user;
|
| public String finduser(String username)
| {
| em.find(Reguser.class, username);
| String email = user.getEmail();
| return email;
| }
| }
|
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