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问题： WEB访问EJB30 有状态bean 的问题
描述: 写了一个有状态的会话bean 在main函数中访问没有问题，当我放到JSP中访问就出现问题了
下面是我的相关代码
远程接口
import javax.ejb.Remote;
@Remote
public interface CountNumber {
public int getnum();
}
有状态Bean实现类
import javax.ejb.Stateful;
import com.thr.stateful.CountNumber;
public @Stateful class CountNumberBean implements CountNumber {
private int k=1;
public int getnum() {
k++;
return k ;
}
}
如果在main函数中这样直接访问
Context cx=new InitialContext();
CountNumber cn=(CountNumber)cx.lookup("CountNumberBean/remote");
System.out.println(cn.getnum());
Thread.sleep(2000);
CountNumber cn2=(CountNumber)cx.lookup("CountNumberBean/remote");
System.out.println(cn2.getnum());
就可以获得两个值，都是 2
但我想要在WEB应用中访问，就出错，这里是我的JSP页面
<%@ page language="java" pageEncoding="ISO-8859-1"%>
<%@page import="com.thr.stateful.CountNumber"%>
<%@page import="javax.naming.Context"%>
<%@page import="javax.naming.InitialContext"%>
My JSP
<%
Context cx=new InitialContext();
CountNumber cn=(CountNumber)session.getAttribute("cn");
if(cn==null){
cn=(CountNumber)cx.lookup("CountNumberBean/remote");
session.setAttribute("cn",cn);
}
out.print(cn.getnum());
%>
下面是错误信息
控制台输出的错误信息
11:18:48,453 ERROR [[jsp]] Servlet.service() for servlet jsp threw exception java.lang.ClassCastException: $Proxy222 at org.apache.jsp.welcome_jsp._jspService(welcome_jsp.java:73) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:373) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:336) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175) at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:179) at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:262) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:446) at java.lang.Thread.run(Thread.java:595)
这里是页面输出的错误信息
org.apache.jasper.JasperException: An exception occurred processing JSP page /welcome.jsp at line 15
12: Context cx=new InitialContext();
13: CountNumber cn=(CountNumber)session.getAttribute("cn");
14: if(cn==null){
15: cn=(CountNumber)cx.lookup("CountNumberBean/remote");
16: session.setAttribute("cn",cn);
17: }
18:
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:504)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:415)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:336)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
root cause
java.lang.ClassCastException: $Proxy222
org.apache.jsp.welcome_jsp._jspService(welcome_jsp.java:73)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:373)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:336)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
note The full stack trace of the root cause is available in the JBossWeb/2.0.1.GA logs.
请帮我诊断诊断，是否是EJB容器的问题呢？
PS：我的开发环境是 JDK1.5+JBOSSIDE for eclipse
解决方案1: 你换个开发环境吧，使用MyEclipse6.5 以及 JBOSS5.0 +JDK6.0用 ，这样就应该不会有什么问题了
解决方案2: CountNumber cn=(CountNumber)session.getAttribute("cn");
加个断点看看
以上介绍了“ WEB访问EJB30 有状态bean 的问题”的问题解答，希望对有需要的网友有所帮助。
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