iReport + jasperReport的一个问题

Question

代码如下：
<%@page contentType="application/pdf;charset=GB2312"%>
<jsp:directive.page import="com.xit.classes.check" />
<jsp:directive.page import="com.xit.classes.Firm" />
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ page import="net.sf.jasperreports.engine.*" %>
<%@ page import="net.sf.jasperreports.engine.util.*" %>
<%@ page import="net.sf.jasperreports.engine.export.*" %>
<%@ page import="java.util.*" %>
<%@ page import="java.io.*" %>
<%@page import="java.sql.*"%><%
String strdate = check.getStringDateShort();
String sql = "select * from pjb_jhdz";
Firm firm = new Firm();
// 创建连接
Connection con = firm.getCon();
try {
Statement sta = con.createStatement();
ResultSet rs = sta.executeQuery(sql);
///查找报表文件
File reportFile = new File(application
.getRealPath("report/bbb.jasper"));

JasperReport jasperReport = (JasperReport)JRLoader.loadObject(reportFile.getPath()); ////////生成pdf文件
Map parameters = new HashMap();
parameters.put("rpttoday", strdate);  

//new JRResultSetDataSource(rs)
JasperPrint jasperPrint = 
JasperFillManager.fillReport(
jasperReport, 
parameters, 
new JRResultSetDataSource(rs)
);

JRHtmlExporter exporter = new JRHtmlExporter(); StringBuffer sbuffer = new StringBuffer(); Map imagesMap = new HashMap();
session.setAttribute("IMAGES_MAP", imagesMap);

exporter.setParameter(JRExporterParameter.JASPER_PRINT, jasperPrint);
exporter.setParameter(JRExporterParameter.OUTPUT_WRITER, out);
exporter.setParameter(JRHtmlExporterParameter.IMAGES_MAP, imagesMap);
exporter.setParameter(JRHtmlExporterParameter.IMAGES_URI, "image.jsp?image=");

exporter.exportReport();
   // 
rs.close();
exporter.reset();
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
%>运行时，能正常输出html页面，但是在后台提示报错：Servlet.service() for servlet jsp threw exception
java.lang.IllegalStateException: getOutputStream() has already been called for this response
at org.apache.catalina.connector.Response.getWriter(Response.java:596)
at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:186)
at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:124)
at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:117)
at org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:191)
at org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:115)
at org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:75)
at org.apache.jsp.Page.abc_jsp._jspService(org.apache.jsp.Page.abc_jsp:116)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:322)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:291)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.xit.classes.filter.doFilter(filter.java:27)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.xit.classes.filter.doFilter(filter.java:27)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:595)请大家帮忙看看，该怎么解决这个报错问题。

Answer 1

把<%%>以外的空格和回车都去掉

Answer 2

Java.lang.IllegalStateException: getOutputStream() has already been called for this response在写JSP程序的时候，如果程序中调用了response.getOutputStream()去向客户端输出文件等数据流,容器就会抛出这样的异常。产生这样的异常原因:是web容器生成的servlet代码中有out.write(""),这个和JSP中调用的response.getOutputStream()产生冲突.即Servlet规范说明，不能既调用response.getOutputStream()，又调用response.getWriter(),无论先调用哪一个，在调用第二个时候应会抛出IllegalStateException，因为在jsp中，out变量实际上是通过response.getWriter得到的，你的程序中既用了response.getOutputStream，又用了out变量，故出现以上错误。Erp100博客r‑m6f e-M[1][1]M8_
　　解决方案：在程序的最后添加：out.clear(); out = pageContext.pushBody(); 或者直接用servlet写

Answer 3

将方法提取,然后写到servlet中,关键执行倒出报表后不能有其他的操作,可以通过返回return null来解决这个问题.

Answer 4

就是不要提供相关的视图的渲染(in the controller ,no forward page)就行了,因为一般倒出报表后,不会跳转页面的