To be or not to be !

在JBoss（版本為3.2.3和jboss-4.0.4.GA）上運(yùn)行JSF的時(shí)候，會(huì)出現(xiàn)以下錯(cuò)誤（在TOMCAT上運(yùn)行完全正常），然后在GOOGLE上搜索，在JBoss的官方論壇上發(fā)現(xiàn)解決方案，就是把頁(yè)面上的兩個(gè)JSF taglib都改成WEB-INF/html_basic.tld、WEB-INF/jsf_core.tld就正常了。但在有的版本里卻運(yùn)行正常，如（3.2.5）。

11:31:25,062 ERROR [UIComponentTag] Faces context not found. getResponseWriter w
ill fail. Check if the FacesServlet has been initialized at all in your web.xml.

11:31:25,062 ERROR [[jsp]] Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
??????? at javax.faces.webapp.UIComponentTag.setupResponseWriter(UIComponentTag.
java:615)
??????? at javax.faces.webapp.UIComponentTag.doStartTag(UIComponentTag.java:217)

??????? at org.apache.myfaces.taglib.core.ViewTag.doStartTag(ViewTag.java:71)
??????? at org.apache.jsp.index_jsp._jspx_meth_f_view_0(index_jsp.java:123)
??????? at org.apache.jsp.index_jsp._jspService(index_jsp.java:99)
??????? at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
??????? at javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
??????? at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper
.java:332)
??????? at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:3
14)
??????? at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
??????? at javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
??????? at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:252)
??????? at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:173)
??????? at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDisp
atcher.java:672)
??????? at org.apache.catalina.core.ApplicationDispatcher.processRequest(Applica
tionDispatcher.java:463)
??????? at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationD
ispatcher.java:398)
??????? at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDis
patcher.java:301)
??????? at com.sun.faces.context.ExternalContextImpl.dispatch(ExternalContextImp
l.java:322)
??????? at com.sun.faces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.
java:147)
??????? at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePha
se.java:87)
??????? at com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:200)
??????? at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:117)
??????? at javax.faces.webapp.FacesServlet.service(FacesServlet.java:198)
??????? at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:252)
??????? at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:173)
??????? at org.apache.myfaces.component.html.util.ExtensionsFilter.doFilter(Exte
nsionsFilter.java:112)
??????? at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:202)
??????? at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:173)
??????? at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFi
lter.java:96)
??????? at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:202)
??????? at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:173)
??????? at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperV
alve.java:213)
??????? at org.apache.catalina.core.StandardContextValve.invoke(StandardContextV
alve.java:178)
??????? at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(Securit
yAssociationValve.java:175)
??????? at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValv
e.java:74)
??????? at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.j
ava:126)
??????? at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.j
ava:105)
??????? at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineVal
ve.java:107)
??????? at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.jav
a:148)
??????? at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java
:869)
??????? at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.p
rocessConnection(Http11BaseProtocol.java:664)
??????? at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpo
int.java:527)
??????? at org.apache.tomcat.util.net.MasterSlaveWorkerThread.run(MasterSlaveWor
kerThread.java:112)
??????? at java.lang.Thread.run(Thread.java:595)

對(duì)SQLServer進(jìn)行操作時(shí)，報(bào)“ResultSet can not re-read row data for column” ，究其原因如下（轉(zhuǎn)）：
（1）如果采用jdbc-odbc驅(qū)動(dòng)，那么就必須按照查詢順序來(lái)一次讀取（不論有沒(méi)有image或text類(lèi)型）
（2）如果采用微軟提供的ms sql server jdbc driver，如果查詢語(yǔ)句中，不存在image或text類(lèi)型字段，那么可以按照無(wú)序獲取
（3）如果采用微軟提供的ms sql server jdbc driver，如果查詢語(yǔ)句中，存在image或text類(lèi)型字段，那么就必須按照順序讀取，否則就會(huì)報(bào)告Driver]ResultSet can not re-read row data for column之類(lèi)的錯(cuò)誤
（4）如果想不查詢語(yǔ)句中有沒(méi)有image或text類(lèi)型字段，都可以不按照順序獲取，或重復(fù)獲取。那么就必須更換驅(qū)動(dòng)，改用第三方的。