java中zip文件的动态压缩和下载[重复]

Question

我正在尝试创建一个 zip 文件并通过单击 jsf 中的链接下载相同的文件。 我无法查看创建的 zip 文件，也无法下载它。我在后端收到以下异常以及 nullpointer 异常。 java.lang.IllegalStateException：Servlet 响应已使用流，无法编写器

请仔细阅读下面的代码并在这方面帮助我。

//I am calling downloadZip2() method on click of the command link in jsf
public void downloadZip2() {
    System.out.println("downloadZip.....................");

    crgAttList = nameDTO.getAttachmentsList();

    // File zipping implementation
    String directoryPath ="G:/attachment";

    logger.info("Directory-Path===" + directoryPath);
    File directoryToZip = new File(directoryPath);

    ArrayList<String> attachmentsList = new ArrayList<String>();

    for (int i = 0; i < crgAttList .size(); i++)
    {           
        attachmentsList.add(crgAttList.get(i).getAttachmentNameWithPath());     
    }

    if (attachmentsList != null && attachmentsList.size() > 0) {
        logger.info("---Creating zip file");
        logger.info("Attachment-List-Size=====>" + attachmentsList.size());
        zipAttachments(attachmentsList, directoryPath + ".zip");
    }

}


public void zipAttachments(List<String> attachmentsList, String zipFileName) {
    byte[] buf = null;
    ZipOutputStream out = null;
    FileInputStream in = null;  
    OutputStream os = null;     

    try {
        FacesContext context = FacesContext.getCurrentInstance();
        HttpServletResponse response = (HttpServletResponse) context.getExternalContext().getResponse();

         response.setContentType("application/zip");
            response.setHeader("Content-Disposition",
                    "attachment;filename=attachment.zip");


        System.out.println(" in zipAttachments before zipFile creation");
        buf = new byte[1024];
        os = new FileOutputStream(zipFileName);
        out = new ZipOutputStream(os);

        out = new ZipOutputStream(response.getOutputStream());


        for (int i = 0; i < attachmentsList.size(); i++) {
            System.out.println(" in zipAttachments for before adding :: "
                    + attachmentsList.get(i) + " file to zip");
            in = new FileInputStream((String) attachmentsList.get(i));
            // Add ZIP entry to output stream.

            out.putNextEntry(new ZipEntry(attachmentsList.get(i).substring(
                    attachmentsList.get(i).indexOf(".") + 1)));
            // Transfer bytes from the file to the ZIP file
            int len = 0;
            while ((len = in.read(buf)) > 0) {
                out.write(buf, 0, len);
            }
            // Complete the entry               

            in.close();             
            out.flush();
            out.closeEntry();


            System.out.println(" in zipAttachments for:: "
                    + attachmentsList.get(i) + " file is added to zip");                    
        }                       

        System.out.println(" in zipAttachments after zipFile creation");            

        System.out.println(" in zipAttachments after out.close");

         out.close();

    } catch (Exception e) {
        System.out.println(" in zipAttachments error" + e);
        e.printStackTrace();
    }   

}

例外

java.lang.IllegalStateException: Servlet response already use stream, Writer not possible
at org.ajax4jsf.webapp.FilterServletResponseWrapper.getWriter(FilterServletResponseWrapper.java:207)
at com.sun.facelets.FaceletViewHandler.createResponseWriter(FaceletViewHandler.java:400)
at com.sun.facelets.FaceletViewHandler.renderView(FaceletViewHandler.java:557)
at org.ajax4jsf.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:100)
at org.ajax4jsf.application.AjaxViewHandler.renderView(AjaxViewHandler.java:176)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:109)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:266)
at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:292)
at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
at org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:178)
at org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:290)
at org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:390)
at org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:517)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
at org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:341)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)




javax.servlet.ServletException
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:277)
at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:292)
at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
at org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:178)
at org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:290)
at org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:390)
at org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:517)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
at org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:341)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)




Caused by: java.lang.NullPointerException
at com.sun.facelets.util.DevTools.writeVariables(DevTools.java:168)
at com.sun.facelets.util.DevTools.writeVariables(DevTools.java:145)
at com.sun.facelets.util.DevTools.debugHtml(DevTools.java:109)
at com.sun.facelets.FaceletViewHandler.handleRenderException(FaceletViewHandler.java:677)
at com.sun.facelets.FaceletViewHandler.renderView(FaceletViewHandler.java:646)
at org.ajax4jsf.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:100)
at org.ajax4jsf.application.AjaxViewHandler.renderView(AjaxViewHandler.java:176)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:109)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:266)

Answer 1

使用

FacesContext.getCurrentInstance().responseComplete();

在您向其写入数据后，阻止 JSF 试图弄乱响应。