文件压缩下载，Feign文件流传递

1、文件下载

将 HttpServletResponse对象通过接口参数传递至后端代码，然后在HttpServletResponse对象中获取到返回给前端的文件输出流：

OutputStream out = httpServletResponse.getOutputStream();

将需要下载的文件通过输出流返回至前端。

1.  
   @Override
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   public void downloadFile(String fileId, String componentId, String folderName, HttpServletResponse response) {
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   WorkPaperCatalogDO workPaperCatalogDO = workPaperCatalogService.getFile(componentId, fileId, false);
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   if (workPaperCatalogDO == null) {
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   return;
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   }
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   try (InputStream inputStream = fileStorageService.getFile(componentId, workPaperCatalogDO.getFolderName(), workPaperCatalogDO.getFileId())) {
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   if (inputStream == null) {
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    return;
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    }
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    response.setCharacterEncoding("utf-8");
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    response.setContentType("application/octet-stream");
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    response.setHeader("Content-Disposition",
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    "attachment;fileName=" URLEncoder.encode(workPaperCatalogDO.getFileName(), "UTF-8"));
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    response.setHeader("Access-Control-Expose-Headers", "*");
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    IOUtils.copy(inputStream, response.getOutputStream());
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    } catch (IOException e) {
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    e.printStackTrace();
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    }
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    }

2、压缩导出

通过使用ZipOutputStream对象，将文件进行压缩，然后导出

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   @ApiOperation("下载文件")
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   @RequestMapping(value = "generateAuditProcFile", method = RequestMethod.GET)
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   public void editAuditProcedure(HttpServletResponse httpServletResponse, @RequestParam String componentId) throws IOException {
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   String fileName = "测试压缩文件.zip";
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   httpServletResponse.setHeader("Content-Disposition", "attachment;filename=" URLEncoder.encode(fileName, "UTF-8"));
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   ByteArrayOutputStream byteArrayOutputStream = auditProcedureService.generateAuditProcFile(componentId);
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   if(byteArrayOutputStream == null) {
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   throw new BusinessException("获取审计程序文件失败");
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    }
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    //转换压缩文件
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    ZipOutputStream zipOutputStream = new ZipOutputStream(httpServletResponse.getOutputStream());
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    zipOutputStream.putNextEntry(new ZipEntry("测试压缩文件.xlsx"));
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    InputStream inputStream = new ByteArrayInputStream(byteArrayOutputStream.toByteArray());
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    IOUtils.copy(inputStream, zipOutputStream);
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    inputStream.close();
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    zipOutputStream.closeEntry();
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    zipOutputStream.finish();
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    zipOutputStream.flush();
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    }

3、通过Feign调用传递输出流

定义Feign接口，该接口返回参数定义 Response，来自feign.Response，定义该接口时，不需要关注对方接口的HttpServletResponse参数。

1.  
   @FeignClient(name = "swworkpaper", url = "${gsum.service.workpaper_url}")
2.  
   public interface WorkpaperFeignService {
3.  
   @RequestMapping(value = "/api/auditProcedureTailor/generateAuditProcFile",method = RequestMethod.GET)
4.  
   Response generateAuditProcFile(@RequestParam("componentId") String componentId);
5.  
   }

调用该接口后，收到Response返回对象，将该对象中的body数据转为输入流

1.  
   //调用Feign接口，获取输出流到Response对象
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   Response fileInputStream = workpaperFeignService.generateAuditProcFile(componentId);
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   //将返回流中的body数据转为输入流
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   inputStream = fileInputStream.body().asInputStream();
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   //输入流转为压缩数据流
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   ZipInputStream zipInputStream = new ZipInputStream(inputStream);
7.  
   //可以进行解压处理，或者进行数据下载，此处进行解压处理，然后统一进行压缩，下载
8.  
   ZipEntry entry;
9.  
   while ((entry = zipInputStream.getNextEntry()) != null){
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    log.info("unziping：" entry);
11.  
    zipOutputStream.putNextEntry(entry);
12.  
    byte buf[] = new byte[1024];
13.  
    int length;
14.  
    while ((length = zipInputStream.read(buf)) > 0) {
15.  
    zipOutputStream.write(buf, 0, length);
16.  
    }
17.  
    zipOutputStream.closeEntry();
18.  
    }
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