一个dlog4j空指针问题

Question

java.lang.NullPointerException
at com.liusoft.dlog4j.dao.DAO.getBean(DAO.java:147)
at com.liusoft.dlog4j.dao.SiteDAO.getSiteByID(SiteDAO.java:73)
at com.liusoft.dlog4j.velocity.DLOG_VelocityTool.site(DLOG_VelocityTool.java:395)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:295)
at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:245)
at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:203)
at org.apache.velocity.runtime.parser.node.ASTReference.value(ASTReference.java:419)
at org.apache.velocity.runtime.parser.node.ASTExpression.value(ASTExpression.java:73)
at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(ASTSetDirective.java:125)
at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:74)
at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:88)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at org.apache.velocity.runtime.directive.Parse.render(Parse.java:224)
at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:170)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at org.apache.velocity.runtime.directive.Parse.render(Parse.java:224)
at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:170)
at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:74)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:107)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at org.apache.velocity.runtime.directive.VelocimacroProxy.render(VelocimacroProxy.java:194)
at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:170)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at org.apache.velocity.runtime.directive.Parse.render(Parse.java:224)
at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:170)
at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:74)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:107)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at org.apache.velocity.Template.merge(Template.java:254)
at org.apache.velocity.tools.view.servlet.VelocityLayoutServlet.mergeTemplate(VelocityLayoutServlet.java:224)
at org.apache.velocity.tools.view.servlet.VelocityViewServlet.doRequest(VelocityViewServlet.java:551)
at com.liusoft.dlog4j.servlet.DLOG_VelocityServlet.doRequest(DLOG_VelocityServlet.java:99)
at org.apache.velocity.tools.view.servlet.VelocityViewServlet.doGet(VelocityViewServlet.java:507)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
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 com.liusoft.dlog4j.servlet.DLOG_HibernateFilter.doFilter(DLOG_HibernateFilter.java:73)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at com.liusoft.dlog4j.servlet.GZIPFilter.doFilter(GZIPFilter.java:60)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
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(Thread.java:595)