ejb+weblogic的使用

[cheer1226]

我先建了一个ejb项目(ejb3_20120330)，只出来一个，没有像书上那样，出来三个项目，我实体用myeclipse的ejb... 逆向工程生成，然后实体，方法都有了，我就导出为ejb3base.jar,再建了一个web项目(ejb3_20120330web)，把ejb3base.jar放在lib里，src下写了一个servlet,(Test.java),
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

TbGyDm dmentity=new TbGyDm();
dmentity.setIcode(1);
dmentity.setSassistname("cheer");
dmentity.setSvalue("gg");
System.out.println("cheer------------");
//tbGyDmFacadeLocal.save(dmentity);
tbGyDmFacadeRemote.save(dmentity);//这里报空指针

}
按理说现在是一个普通的web项目，我打包成war,部署到weblogic9.2下，404错误， 请教一下 我这个思路有错吗？ 为什么404错误
我看web.xml里是这样 <servlet-mapping>
<servlet-name>Test</servlet-name>
<url-pattern>/servlet/Test</url-pattern>
</servlet-mapping>
就把地址改为http://localhost:8080/ejb3_20120330web/servlet/Test 这次报500，weblogic错误是：
Error 500--Internal Server Error
java.lang.NullPointerException
at controller.Test.doGet(Test.java:50)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:743)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:283)
at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
at weblogic.servlet.internal.RequestEventsFilter.doFilter(RequestEventsFilter.java:26)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3229)
at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:121)
at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2002)
at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:1908)
at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1362)
at weblogic.work.ExecuteThread.execute(ExecuteThread.java:209)
at weblogic.work.ExecuteThread.run(ExecuteThread.java:181)