Question

目标：在Liferay Portlet内打开本地网络外的PDF链接。我可以使用window.open在portlet中显示PDF。 PDF从内部数据库服务器下载并显示在网络外部。从一个JSP传递链接（使用serveResourse从DB获取链接并在portlet中显示它）到另一个JSP“showPDF.jsp”。代码一直有效，直到ServletOutputStream pdfout = response.getOutputStream();生成错误。为什么我有这些错误？

<%@ page import="java.util.*,java.net.*,java.io.*" %>
<%@ page import="org.apache.commons.httpclient.*" %>
<%@ page import="org.apache.commons.codec.binary.Base64" %>
<%@ page import="org.apache.commons.httpclient.methods.*" %>
<%@ page import="org.apache.commons.httpclient.params.HttpMethodParams" %>
<%@ page import="org.apache.commons.httpclient.util.URIUtil" %>
<%@ page import="javax.servlet.http.HttpServletResponseWrapper" %>
<%@ page import= "com.liferay.portal.kernel.util.ParamUtil"%>
<%@ page import="javax.portlet.PortletPreferences"%>
<%@ taglib uri="http://java.sun.com/portlet" prefix="portlet" %>
<script type="text/javascript">
alert("showPDF");
</script>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
String queryString=ParamUtil.getString(request,"urlPDF");
String urlPDF=queryString.substring(0, queryString.indexOf("?"));
String queryPDF[]=queryString.substring(queryString.indexOf("?"),queryString.length()).split("&");
HttpClient m_httpClient = new HttpClient();
GetMethod getMethod = new GetMethod(urlPDF);
getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler(3,false));
NameValuePair[] params=new NameValuePair[queryPDF.length];
for(int i=0;i<queryPDF.length;i++)
    {
    NameValuePair param=new NameValuePair(queryPDF[i].split("=")[0],queryPDF[i].split("=")[1]);
    params[i]=param;
    }
getMethod.setQueryString(params);
byte[] responsePDF = null;
try {
    int statusCode=m_httpClient.executeMethod(getMethod);
    if (statusCode !=HttpStatus.SC_OK) {
        System.err.println("Method fails: " + getMethod.getStatusLine());
        }

//response
responsePDF = getMethod.getResponseBody();

//display response in console
//System.out.println(new String(responsePDF));//display

int length=responsePDF.length;
System.out.println(length);
response.flushBuffer();
response.setContentType("application/pdf");
response.setContentLength(length);
ServletOutputStream pdfout = response.getOutputStream();
pdfout.write(responsePDF,0,length);
pdfout.flush();
pdfout.close();
    } catch (HttpException e) {
     System.err.println("Fatal protocol violation: " + e.getMessage());
     e.printStackTrace();
    } catch (IOException e) {
     System.err.println("Fatal transport error: " + e.getMessage());
     e.printStackTrace();

    } finally {
            //release connection    
            getMethod.releaseConnection();
    }
%>

错误：

23:08:10,170 ERROR [http-bio-8080-exec-218][PortletRequestDispatcherImpl:115] org.apache.jasper.JasperException: An exception occurred processing JSP page /html/showPDF.jsp at line 75

72:         //response.setProperty(com.liferay.portal.kernel.HttpHeaders.CONTENT_DISPOSITION,"attachment,filename=filename");
73:         // ServletOutputStream pdfout = response.getOutputStream();
74:         response.setContentLength(length);
75:         ServletOutputStream pdfout = response.getOutputStream();
76:         pdfout.write(responsePDF,0,length);
77:         pdfout.flush();
78:         pdfout.close();

堆栈跟踪：

org.apache.jasper.JasperException: An exception occurred processing JSP page /html/showPDF.jsp at line 75

72:         //response.setProperty(com.liferay.portal.kernel.HttpHeaders.CONTENT_DISPOSITION,"attachment,filename=filename");
73:         // ServletOutputStream pdfout = response.getOutputStream();
74:         response.setContentLength(length);
75:         ServletOutputStream pdfout = response.getOutputStream();
76:         pdfout.write(responsePDF,0,length);
77:         pdfout.flush();
78:         pdfout.close();

堆栈跟踪：

    at org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:465)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:96)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:749)
    at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:605)
    at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:544)
    at com.liferay.portlet.PortletRequestDispatcherImpl.dispatch(PortletRequestDispatcherImpl.java:331)
    at com.liferay.portlet.PortletRequestDispatcherImpl.include(PortletRequestDispatcherImpl.java:112)
    at com.liferay.util.bridges.mvc.MVCPortlet.include(MVCPortlet.java:371)
    at com.liferay.util.bridges.mvc.MVCPortlet.include(MVCPortlet.java:387)
    at com.liferay.util.bridges.mvc.MVCPortlet.doDispatch(MVCPortlet.java:320)
    at javax.portlet.GenericPortlet.render(GenericPortlet.java:233)
    at com.liferay.portlet.FilterChainImpl.doFilter(FilterChainImpl.java:103)
    at com.liferay.portlet.ScriptDataPortletFilter.doFilter(ScriptDataPortletFilter.java:55)
    at com.liferay.portlet.FilterChainImpl.doFilter(FilterChainImpl.java:100)
    at com.liferay.portal.kernel.portlet.PortletFilterUtil.doFilter(PortletFilterUtil.java:64)
    at com.liferay.portal.kernel.servlet.PortletServlet.service(PortletServlet.java:112)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:96)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:749)
    at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:605)
    at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:544)
    at com.liferay.portlet.InvokerPortletImpl.invoke(InvokerPortletImpl.java:604)
    at com.liferay.portlet.InvokerPortletImpl.invokeRender(InvokerPortletImpl.java:677)
    at com.liferay.portlet.InvokerPortletImpl.render(InvokerPortletImpl.java:379)
    at org.apache.jsp.html.portal.render_005fportlet_jsp._jspService(render_005fportlet_jsp.java:1230)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at com.liferay.portal.servlet.DirectRequestDispatcher.include(DirectRequestDispatcher.java:57)
    at com.liferay.portal.servlet.ClassLoaderRequestDispatcherWrapper.doDispatch(ClassLoaderRequestDispatcherWrapper.java:78)
    at com.liferay.portal.servlet.ClassLoaderRequestDispatcherWrapper.include(ClassLoaderRequestDispatcherWrapper.java:53)
    at com.liferay.portlet.PortletContainerImpl._doRender(PortletContainerImpl.java:655)
    at com.liferay.portlet.PortletContainerImpl.render(PortletContainerImpl.java:138)
    at com.liferay.portlet.SecurityPortletContainerWrapper.render(SecurityPortletContainerWrapper.java:141)
    at com.liferay.portlet.RestrictPortletContainerWrapper.render(RestrictPortletContainerWrapper.java:126)
    at com.liferay.portal.kernel.portlet.PortletContainerUtil.render(PortletContainerUtil.java:156)
    at com.liferay.portal.layoutconfiguration.util.PortletRenderer._render(PortletRenderer.java:120)
    at com.liferay.portal.layoutconfiguration.util.PortletRenderer.render(PortletRenderer.java:72)
    at com.liferay.portal.layoutconfiguration.util.RuntimePageImpl.doProcessTemplate(RuntimePageImpl.java:460)
    at com.liferay.portal.layoutconfiguration.util.RuntimePageImpl.doDispatch(RuntimePageImpl.java:284)
    at com.liferay.portal.layoutconfiguration.util.RuntimePageImpl.processTemplate(RuntimePageImpl.java:113)
    at com.liferay.portal.layoutconfiguration.util.RuntimePageImpl.processTemplate(RuntimePageImpl.java:124)
    at com.liferay.portal.layoutconfiguration.util.RuntimePageUtil.processTemplate(RuntimePageUtil.java:69)
    at org.apache.jsp.html.portal.layout.view.portlet_jsp._jspService(portlet_jsp.java:553)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:96)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:749)
    at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:605)
    at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:544)
    at com.liferay.portal.action.LayoutAction.includeLayoutContent(LayoutAction.java:280)
    at com.liferay.portal.action.LayoutAction.processLayout(LayoutAction.java:383)
    at com.liferay.portal.action.LayoutAction.doExecute(LayoutAction.java:178)
    at com.liferay.portal.action.LayoutAction.execute(LayoutAction.java:79)
    at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
    at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
    at com.liferay.portal.struts.PortalRequestProcessor.process(PortalRequestProcessor.java:173)
    at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
    at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
    at com.liferay.portal.servlet.MainServlet.callParentService(MainServlet.java:546)
    at com.liferay.portal.servlet.MainServlet.service(MainServlet.java:523)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
    at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
    at com.liferay.portal.servlet.filters.secure.SecureFilter.processFilter(SecureFilter.java:293)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
    at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
    at com.liferay.portal.servlet.filters.jsoncontenttype.JSONContentTypeFilter.processFilter(JSONContentTypeFilter.java:42)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:96)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:749)
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:487)
    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:412)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:339)
    at com.liferay.portal.servlet.FriendlyURLServlet.service(FriendlyURLServlet.java:160)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
    at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
    at com.liferay.portal.servlet.filters.strip.StripFilter.processFilter(StripFilter.java:359)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
    at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
    at com.liferay.portal.servlet.filters.gzip.GZipFilter.processFilter(GZipFilter.java:123)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
    at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
    at com.liferay.portal.servlet.filters.secure.SecureFilter.processFilter(SecureFilter.java:293)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
    at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
    at com.liferay.portal.servlet.filters.i18n.I18nFilter.processFilter(I18nFilter.java:243)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
    at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
    at com.liferay.portal.servlet.filters.jsoncontenttype.JSONContentTypeFilter.processFilter(JSONContentTypeFilter.java:42)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
    at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
    at com.liferay.portal.servlet.filters.autologin.AutoLoginFilter.processFilter(AutoLoginFilter.java:267)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
    at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
    at com.liferay.portal.servlet.filters.sso.ntlm.NtlmPostFilter.processFilter(NtlmPostFilter.java:83)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
    at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
    at com.liferay.portal.sharepoint.SharepointFilter.processFilter(SharepointFilter.java:88)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
    at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
    at com.liferay.portal.servlet.filters.virtualhost.VirtualHostFilter.processFilter(VirtualHostFilter.java:226)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:185)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:96)
    at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:738)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:165)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:96)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:165)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:96)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:185)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:96)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:96)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IllegalStateException: Unable to obtain OutputStream because Writer is already in use
    at com.liferay.portlet.MimeResponseImpl.getPortletOutputStream(MimeResponseImpl.java:75)
    at com.liferay.portlet.PortletServletResponse.getOutputStream(PortletServletResponse.java:188)
    at org.apache.jsp.html.showPDF_jsp._jspService(showPDF_jsp.java:152)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    ... 181 more

Answer 1

您希望在同一响应中组合文本和二进制文件，但这是不可能的（请参阅ServletResponse文档http://docs.oracle.com/javaee/6/api/javax/servlet/ServletResponse.html#getWriter%28%29）。它只是说响应已经调用了getWriter（用于发送文本）。这就是为什么你不能调用用于二进制数据的getOutputStream。可能是因为您在页面顶部有这个脚本，它由JSP引擎隐式地呈现为文本。对此问题有很多好的回答，请查看以下内容：

getOutputStream() has already been called for this response
Servlets in java - both getWriter() and getOutputStream()
How do I use getOutputStream() and getWriter() in the same servlet request?
等。搜索stackoverflow：getwriter getoutputstream

在Liferay portlet中显示链接PDF

1 个答案: