代碼

參數：

1.filePath:文件的絕對路徑（d:downloada.xlsx）

2.fileName(a.xlsx)

3.編碼格式(GBK)

4.response、request不介紹了，從控制器傳入的http對象

代碼片.

//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('失敗'); }//下載方法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); //判斷下載類型 xlsx 或 xls 現在只實現了xlsx、xls兩個類型的文件下載 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瀏覽器 fileName = URLEncoder.encode(fileName, 'UTF8');} else if (StringUtils.contains(userAgent, 'Mozilla')) {// google,火狐瀏覽器 fileName = new String(fileName.getBytes(), 'ISO8859-1');} else { fileName = URLEncoder.encode(fileName, 'UTF8');// 其他瀏覽器}response.setHeader('Content-disposition', 'attachment; filename=' + fileName); } catch (UnsupportedEncodingException e) {logger.error(e.getMessage(), e);return false; } InputStream in = null; OutputStream out = null; try {//獲取要下載的文件輸入流in = new FileInputStream(filePath);int len = 0;//創建數據緩沖區byte[] buffer = new byte[1024];//通過response對象獲取outputStream流out = response.getOutputStream();//將FileInputStream流寫入到buffer緩沖區while((len = in.read(buffer)) > 0) { //使用OutputStream將緩沖區的數據輸出到瀏覽器 out.write(buffer,0,len);}//這一步走完，將文件傳入OutputStream中后，頁面就會彈出下載框 } 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('不支持的下載類型！'); return false; } }

實現效果

1.火狐瀏覽器效果

2.chrome效果，自動下載

補充知識：文件上傳/下載的幾種寫法(java后端)

文件上傳

1、框架已經幫你獲取到文件對象File了

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、天了個擼，SB架構師根本就飄在天空沒下來，根本就沒想文件上傳這一回事

public String uploadByHttp(HttpServletRequest request) throws Exception{ String filePath=null; List<String> fileNames = new ArrayList<>(); //創建一個通用的多部分解析器 CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver(request.getSession().getServletContext()); //判斷 request 是否有文件上傳,即多部分請求 if(multipartResolver.isMultipart(request)){//轉換成多部分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，我正在擼框架，請問HttpServletRequest怎么獲?。。。?！

(1)在web.xml中配置一個監聽

<listener> <listener-class> org.springframework.web.context.request.RequestContextListener </listener-class> </listener>

(2)HttpServletRequest request = ((ServletRequestAttributes)RequestContextHolder.getRequestAttributes()).getRequest();

文件下載（直接用鏈接下載的不算），這比較簡單

1、本地文件下載（即文件保存在本地）

public void fileDownLoad(HttpServletRequest request,HttpServletResponse response,String fileName,String filePath) throws Exception { response.setCharacterEncoding('UTF-8'); //設置ContentType字段值 response.setContentType('text/html;charset=utf-8'); //通知瀏覽器以下載的方式打開 response.addHeader('Content-type', 'appllication/octet-stream'); response.addHeader('Content-Disposition', 'attachment;filename='+fileName); //通知文件流讀取文件 InputStream in = request.getServletContext().getResourceAsStream(filePath); //獲取response對象的輸出流 OutputStream out = response.getOutputStream(); byte[] buffer = new byte[1024]; int len; //循環取出流中的數據 while((len = in.read(buffer)) != -1){ out.write(buffer,0,len); } }

2、遠程文件下載（即網上資源下載，只知道文件URI）

public static void downLoadFromUrl(String urlStr,String fileName,HttpServletResponse response){ try { urlStr=urlStr.replaceAll('', '/'); URL url = new URL(urlStr); HttpURLConnection conn = (HttpURLConnection)url.openConnection(); //設置超時間為3秒 conn.setConnectTimeout(3*1000); //防止屏蔽程序抓取而返回403錯誤 conn.setRequestProperty('User-Agent', 'Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)');//得到輸入流 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'));//獲取響應報文輸出流對象 //獲取response對象的輸出流 OutputStream out = response.getOutputStream(); byte[] buffer = new byte[1024]; int len; //循環取出流中的數據 while((len = in.read(buffer)) != -1){ out.write(buffer,0,len); } } catch (Exception e) { e.printStackTrace(); } }

以上這篇Java后臺Controller實現文件下載操作就是小編分享給大家的全部內容了，希望能給大家一個參考，也希望大家多多支持好吧啦網。