java.lang.IllegalStateException: getOutputStream() has already been called for this response
at org.apache.catalina.connector.Response.getWriter(Response.java:564)
at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:212)
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.processTemplate(FreeMarkerView.java:366)
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.doRender(FreeMarkerView.java:283)
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.renderMergedTemplateModel(FreeMarkerView.java:233)
at org.springframework.web.servlet.view.AbstractTemplateView.renderMergedOutputModel(AbstractTemplateView.java:167)
at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:250)
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1047)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:817)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:560)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at com.airport.common.web.ProcessTimeFilter.doFilter(ProcessTimeFilter.java:35)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:94)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:496)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1156)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1539)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1495)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
<div class="body-box"> <@p.form id="jvForm" action="v_import.do" labelWidth="12" class="form-inline" enctype="multipart/form-data" onsubmit="return false;"> <@p.td id="linkLogo" label="文件路径"> <span id="ufc0" style="position:relative"> <input id=‘uploadFileText0‘ name="filepath" type=‘text‘ class="btn btn-default" size="14" readonly="true" /> <input id="uploadBrower" class="browse btn btn-default" type=‘button‘ value=‘浏览‘/> <input id="uploadFile0" name="file" onchange="$(‘#uploadFileText0‘).val(this.value);" size="14" type="file" class="file-button btn btn-default"/> </span> <input id="uploadButton" class="upload-button btn btn-default" type="button" value="导入" /> <input id="templateButton" class="btn btn-default" type="button" value="模板下载" /><br/> <input id="success" type="hidden" value="${success!}" /> <input id="exceptionInfo" type="hidden" value="${exceptionInfo!‘‘}" /> <input id="defaultExceptionInfo" type="hidden" value="导入失败！" /> </@p.td> </@p.form> </div>
当点击上边‘模板下载‘按钮时，提交表单，js逻辑为：
<script type="text/javascript"> $(function() { // 点击下载模板 $("#templateButton").bind("click",function(){ downloadTemplate(); }); }); /* * 下载证书导入数据模板 */ function downloadTemplate() { var form = document.getElementById("jvForm"); form.action = "v_download_template.do"; form.encoding = "application/x-www-form-urlencoded"; form.submit(); } </script>
下载逻辑全部在后台，前台使用freemarker及html，下载使用的后台代码：
controller：
@RequestMapping("/certificate_import/v_download_template.do")
public String downloadTemplate(HttpServletRequest request, HttpServletResponse response) {
log.info("下载证书导入模板...");
File template = cmsCertificateImportMng.getCertificateDataTemplate();
if (template == null) {
log.warn("没有获取到证书数据导入模板文件，下载失败");
return "certificate_import/list";
}
// 将文件流写入response
FileDownloadUtils.writeFile2Response(response, template);
return "certificate_import/import";
}
public static void writeFile2Response(HttpServletResponse response, File template) { response.setContentType("application/x-download;charset=UTF-8"); response.addHeader("Content-disposition", "filename=" + template.getName()); OutputStream os = null; ServletOutputStream ros = null; try { ros = response.getOutputStream(); os = new BufferedOutputStream(ros); byte[] bs = FileUtils.toByteArray(template); os.write(bs); os.flush(); ros.flush(); } catch (IOException e) { log.error("意外的异常：", e); } finally { if (os != null) { try { os.close(); } catch (IOException e) { log.error("意外的异常：", e); } } if (ros != null) { try { ros.flush(); ros.close(); } catch (IOException e) { log.error("意外的异常：", e); } } } }
@RequestMapping("/certificate_import/v_download_template.do")
public void downloadTemplate(HttpServletRequest request, HttpServletResponse response) {
log.info("下载证书导入模板...");
File template = cmsCertificateImportMng.getCertificateDataTemplate();
if (template == null) {
log.warn("没有获取到证书数据导入模板文件，下载失败");
return;
}
// 将文件流写入response
FileDownloadUtils.writeFile2Response(response, template);
}
原文：https://www.cnblogs.com/xhj123/p/12391457.html