错误：
java.lang.IllegalStateException: getOutputStream() has already been called for this response at org.apache.catalina.connector.Response.getWriter(Response.java:604) at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:198) at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:125) at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:118) at org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:186) at org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:118) at org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:77) at org.apache.jsp.project.flowManage.pic_jsp._jspService(pic_jsp.java:88) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at com.Space_debris.filter.ChangeCharsetFilter.doFilter(ChangeCharsetFilter.java:28) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:261) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:581) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447) at java.lang.Thread.run(Thread.java:619)
根据提示，找到pic_jsp.java:88 是：
finally { _jspxFactory.releasePageContext(_jspx_page_context); }
这里是在释放在jsp中使用的对象，会调用response.getWriter(),因为这个方法是和
response.getOutputStream()相冲突的！所以会出现以上这个异常。
解决方法是：
在使用完输出流以后调用以下两行代码即可：
out.clear();
out = pageContext.pushBody();
解决问题参考：http://blog.163.com/first_lost/blog/static/4441142620093151212263/
