Question

如何正确处理已取消的文件下载？有问题的文件是一个非常大的zip文件，需要很长时间才能构建，因此用户有足够的时间点击下载对话框窗口中的“取消”按钮。

当它发生时，会出现一个讨厌的异常（见下文），这是预期的，因为客户端破坏了管道。但是如何清理呢？ Where /什么是捕获Exception的正确方法，以便tomcat日志不会被它们弄乱？

谢谢。

下载代码本身是教科书中非常标准的代码：

import java.util.zip.ZipEntry
import java.util.zip.ZipOutputStream

def getZipFile(params) {   
  response.setHeader("Expires", "0");
  response.setHeader("Cache-Control", "must-revalidate, post-check=0, pre-check=0");
  response.setHeader("Pragma", "public");
  response.setHeader("Content-Disposition", "attachment; filename=\"filename.zip\"");
  response.contentType = "application/zip"

  def zos = new ZipOutputStream(response.outputStream)
  zos = functionThatCreatesTheZipFile(zos, params) // this takes some time
  zos.close()
}

例外：

rfpmgr [2013-05-01 10:14:32.337] ERROR: web.errors.GrailsExceptionResolver IOException occurred when processing request: [GET] /rfpManager/report/downloadZipFile
Stacktrace follows:
java.io.IOException
at java.util.zip.ZipOutputStream.writeBytes(ZipOutputStream.java:617)
at java.util.zip.ZipOutputStream.writeCEN(ZipOutputStream.java:501)
at java.util.zip.ZipOutputStream.finish(ZipOutputStream.java:348)
at java.util.zip.DeflaterOutputStream.close(DeflaterOutputStream.java:238)
at java.util.zip.ZipOutputStream.close(ZipOutputStream.java:360)
at gov.usgs.eventManager.ZipService.getZipFile(ZipService.groovy:32)
at gov.usgs.eventManager.ReportController$_closure18.doCall(ReportController.groovy:738)
at gov.usgs.jdt.josso.spring.JOSSOProcessingFilter.doFilter(JOSSOProcessingFilter.java:144)
at gov.usgs.jdt.josso.agent.GenericServletSSOAgentFilter.doFilter(GenericServletSSOAgentFilter.java:431)
at java.lang.Thread.run(Thread.java:722)
rfpmgr [2013-05-01 10:14:32.354] ERROR: web.errors.GrailsExceptionResolver IllegalStateException occurred when processing request: [GET] /rfpManager/report/downloadZipFile
getOutputStream() has already been called for this response. Stacktrace follows:
org.codehaus.groovy.grails.web.pages.exceptions.GroovyPagesException: Error processing GroovyPageView: getOutputStream() has already been called for this response
at gov.usgs.jdt.josso.spring.JOSSOProcessingFilter.doFilter(JOSSOProcessingFilter.java:144)
at gov.usgs.jdt.josso.agent.GenericServletSSOAgentFilter.doFilter(GenericServletSSOAgentFilter.java:431)
at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.IllegalStateException: getOutputStream() has already been called for this response
at gsp_rfpManager_errorserrors_gsp.run(gsp_rfpManager_errorserrors_gsp.groovy:17)
... 3 more

Answer 1

这似乎工作正常：

import java.util.zip.ZipEntry
import java.util.zip.ZipOutputStream
import org.apache.catalina.connector.ClientAbortException

def getZipFile(params) {   
  response.setHeader("Expires", "0");
  response.setHeader("Cache-Control", "must-revalidate, post-check=0, pre-check=0");
  response.setHeader("Pragma", "public");
  response.setHeader("Content-Disposition", "attachment; filename=\"filename.zip\"");
  response.contentType = "application/zip"

  try {
    def zos = new ZipOutputStream(response.outputStream)
    zos = functionThatCreatesTheZipFile(zos, params) // this takes some time
    zos.close()
  }
  catch (ClientAbortException ex) {
    println "user aborted download"
  }
}

Answer 2

我可以看到：

引起：java.lang.IllegalStateException：已经为此响应调用了getOutputStream（）

这在Grails控制器直接渲染时很常见。解决方案：

render ( file: <InputStream>, contentType: 'image/jpeg')
//or
render ( file: <byte[]>, contentType: 'image/jpeg')
//or
GrailsWebRequest webRequest = 
             (GrailsWebRequest) RequestContextHolder.currentRequestAttributes()
webRequest.setRenderView(false)

这应该有所帮助。

用户在Grails中取消了文件下载

2 个答案: