在利用jxls导出excel时，报异常：
java.lang.IllegalStateException: getOutputStream() has already been called for this response
如下所示：
java.lang.IllegalStateException: getOutputStream() has already been called for this response
at org.apache.coyote.tomcat5.CoyoteResponse.getWriter(CoyoteResponse.java:599)
at org.apache.coyote.tomcat5.CoyoteResponseFacade.getWriter(CoyoteResponseFacade.java:163)
at javax.servlet.ServletResponseWrapper.getWriter(ServletResponseWrapper.java:111)
at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:122)
at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:115)
at org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:182)
at org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:115)
at org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:75)
at org.apache.jsp.WEB_002dINF.jsp.supplyArea.supplyAreaView_jsp._jspService(supplyAreaView_jsp.java:156)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:704)
at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:590)
at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:510)
at org.apache.struts.chain.commands.servlet.PerformForward.handleAsInclude(PerformForward.java:141)
at org.apache.struts.chain.commands.servlet.PerformForward.perform(PerformForward.java:92)
at org.apache.struts.chain.commands.AbstractPerformForward.execute(AbstractPerformForward.java:54)
at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:305)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)