代码
参数：
1.filePath:文件的绝对路径（d:\download\a.xlsx）
2.fileName(a.xlsx)
3.编码格式(GBK)
4.response、request不介绍了，从控制器传入的http对象
代码片.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 //控制器 @RequestMapping(UrlConstants.BLACKLIST_TESTDOWNLOAD) public void downLoad(String filePath, HttpServletResponse response, HttpServletRequest request) throws Exception { boolean is = myDownLoad("D:\\a.xlsx","a.xlsx","GBK",response,request); if(is) System.out.println("成功"); else System.out.println("失败"); } //下载方法 public boolean myDownLoad(String filePath,String fileName, String encoding, HttpServletResponse response, HttpServletRequest request){ File f = new File(filePath); if (!f.exists()) { try { response.sendError(404, "File not found!"); } catch (IOException e) { e.printStackTrace(); } return false; } String type = fileName.substring(fileName.lastIndexOf(".") + 1); //判断下载类型 xlsx 或 xls 现在只实现了xlsx、xls两个类型的文件下载 if (type.equalsIgnoreCase("xlsx") || type.equalsIgnoreCase("xls")){ response.setContentType("application/force-download;charset=UTF-8"); final String userAgent = request.getHeader("USER-AGENT"); try { if (StringUtils.contains(userAgent, "MSIE") || StringUtils.contains(userAgent, "Edge")) {// IE浏览器 fileName = URLEncoder.encode(fileName, "UTF8"); } else if (StringUtils.contains(userAgent, "Mozilla")) {// google,火狐浏览器 fileName = new String(fileName.getBytes(), "ISO8859-1"); } else { fileName = URLEncoder.encode(fileName, "UTF8");// 其他浏览器 } response.setHeader("Content-disposition", "attachment; filename=" + fileName); } catch (UnsupportedEncodingException e) { logger.error(e.getMessage(), e); return false; } InputStream in = null; OutputStream out = null; try { //获取要下载的文件输入流 in = new FileInputStream(filePath); int len = 0; //创建数据缓冲区 byte[] buffer = new byte[1024]; //通过response对象获取outputStream流 out = response.getOutputStream(); //将FileInputStream流写入到buffer缓冲区 while((len = in.read(buffer)) > 0) { //使用OutputStream将缓冲区的数据输出到浏览器 out.write(buffer,0,len); } //这一步走完，将文件传入OutputStream中后，页面就会弹出下载框 } catch (Exception e) { logger.error(e.getMessage(), e); return false; } finally { try { if (out != null) out.close(); if(in!=null) in.close(); } catch (IOException e) { logger.error(e.getMessage(), e); } } return true; }else { logger.error("不支持的下载类型！"); return false; } } 实现效果
1.火狐浏览器效果
2.chrome效果，自动下载
补充知识：文件上传/下载的几种写法(java后端)
文件上传
1、框架已经帮你获取到文件对象File了
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 public boolean uploadFileToLocale(File uploadFile,String filePath) { boolean ret_bl = false; try { InputStream in = new FileInputStream(uploadFile); ret_bl=copyFile(in,filePath); } catch (Exception e) { e.printStackTrace(); } return ret_bl; } public boolean copyFile(InputStream in,String filePath) { boolean ret_bl = false; FileOutputStream os=null; try { os = new FileOutputStream(filePath,false); byte[] b = new byte[8 * 1024]; int length = 0; while ((length = in.read(b)) > 0) { os.write(b, 0, length); } os.close(); in.close(); ret_bl = true; } catch (Exception e) { e.printStackTrace(); }finally{ try { if(os!=null){ os.close(); } if(in!=null){ in.close(); } } catch (IOException e) { e.printStackTrace(); } } return ret_bl; } } 2、天了个撸，SB架构师根本就飘在天空没下来，根本就没想文件上传这一回事
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 public String uploadByHttp(HttpServletRequest request) throws Exception{ String filePath=null; List<String> fileNames = new ArrayList<>(); //创建一个通用的多部分解析器 CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver(request.getSession().getServletContext()); //判断 request 是否有文件上传,即多部分请求 if(multipartResolver.isMultipart(request)){ //转换成多部分request MultipartHttpServletRequest multiRequest =multipartResolver.resolveMultipart(request); MultiValueMap<String,MultipartFile> multiFileMap = multiRequest.getMultiFileMap(); List<MultipartFile> fileSet = new LinkedList<>(); for(Entry<String, List<MultipartFile>> temp : multiFileMap.entrySet()){ fileSet = temp.getValue(); } String rootPath=System.getProperty("user.dir"); for(MultipartFile temp : fileSet){ filePath=rootPath+"/tem/"+temp.getOriginalFilename(); File file = new File(filePath); if(!file.exists()){ file.mkdirs(); } fileNames.add(temp.getOriginalFilename()); temp.transferTo(file); } } } 3、神啊，我正在撸框架，请问HttpServletRequest怎么获取！！！！
(1)在web.xml中配置一个监听
1 2 3 4 5 <listener> <listener-class> org.springframework.web.context.request.RequestContextListener </listener-class> </listener> (2)HttpServletRequest request = ((ServletRequestAttributes)RequestContextHolder.getRequestAttributes()).getRequest();
文件下载（直接用链接下载的不算），这比较简单
1、本地文件下载（即文件保存在本地）
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 public void fileDownLoad(HttpServletRequest request,HttpServletResponse response,String fileName,String filePath) throws Exception { response.setCharacterEncoding("UTF-8"); //设置ContentType字段值 response.setContentType("text/html;charset=utf-8"); //通知浏览器以下载的方式打开 response.addHeader("Content-type", "appllication/octet-stream"); response.addHeader("Content-Disposition", "attachment;filename="+fileName); //通知文件流读取文件 InputStream in = request.getServletContext().getResourceAsStream(filePath); //获取response对象的输出流 OutputStream out = response.getOutputStream(); byte[] buffer = new byte[1024]; int len; //循环取出流中的数据 while((len = in.read(buffer)) != -1){ out.write(buffer,0,len); } } 2、远程文件下载（即网上资源下载，只知道文件URI）
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 public static void downLoadFromUrl(String urlStr,String fileName,HttpServletResponse response){ try { urlStr=urlStr.replaceAll("\\\\", "/"); URL url = new URL(urlStr); HttpURLConnection conn = (HttpURLConnection)url.openConnection(); //设置超时间为3秒 conn.setConnectTimeout(3*1000); //防止屏蔽程序抓取而返回403错误 conn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)"); //得到输入流 InputStream inputStream = conn.getInputStream(); response.reset(); response.setContentType("application/octet-stream; charset=utf-8"); response.setHeader("Content-Disposition", "attachment; filename=" + new String(fileName.getBytes("GBK"),"ISO8859_1")); //获取响应报文输出流对象 //获取response对象的输出流 OutputStream out = response.getOutputStream(); byte[] buffer = new byte[1024]; int len; //循环取出流中的数据 while((len = in.read(buffer)) != -1){ out.write(buffer,0,len); } } catch (Exception e) { e.printStackTrace(); } }
以上这篇Java后台Controller实现文件下载操作就是小编分享给大家的全部内容了
