Hi there,
Plz help me to overcome the following exception

java.lang.IllegalStateException: getWriter() has already been called for this response
    at org.apache.coyote.tomcat4.CoyoteResponse.getOutput Stream(CoyoteResponse.java:572)
    at org.apache.coyote.tomcat4.CoyoteResponseFacade.get OutputStream(CoyoteResponseFacade.java:156)
    at com.arrow.dpa.controller.ExcelDownload.downloadFil e(ExcelDownload.java:91)
    at com.arrow.dpa.controller.ExcelDownload.downloadFil e(ExcelDownload.java:55)
    at org.apache.jsp.Purchase_ExcelDownload_jsp._jspServ ice(Purchase_ExcelDownload_jsp.java:301)
    at org.apache.jasper.runtime.HttpJspBase.service(Http JspBase.java:137)
    at javax.servlet.http.HttpServlet.service(HttpServlet .java:809)
    at org.apache.jasper.servlet.JspServletWrapper.servic e(JspServletWrapper.java:210)
    at org.apache.jasper.servlet.JspServlet.serviceJspFil e(JspServlet.java:295)
    at org.apache.jasper.servlet.JspServlet.service(JspSe rvlet.java:241)
    at javax.servlet.http.HttpServlet.service(HttpServlet .java:809)