• java实现文件下载功能


    第一种方法:

     1 public HttpServletResponse download(String path, HttpServletResponse response) {
     2     try {
     3       // path是指欲下载的文件的路径。
     4       File file = new File(path);
     5       // 取得文件名。
     6       String filename = file.getName();
     7       // 取得文件的后缀名。
     8       String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase();
     9  
    10       // 以流的形式下载文件。
    11       InputStream fis = new BufferedInputStream(new FileInputStream(path));
    12       byte[] buffer = new byte[fis.available()];
    13       fis.read(buffer);
    14       fis.close();
    15       // 清空response
    16       response.reset();
    17       // 设置response的Header
    18       response.addHeader("Content-Disposition", "attachment;filename=" + new String(filename.getBytes()));
    19       response.addHeader("Content-Length", "" + file.length());
    20       OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
    21       response.setContentType("application/octet-stream");
    22       toClient.write(buffer);
    23       toClient.flush();
    24       toClient.close();
    25     } catch (IOException ex) {
    26       ex.printStackTrace();
    27     }
    28     return response;
    29   }
    30  
    31   public void downloadLocal(HttpServletResponse response) throws FileNotFoundException {
    32     // 下载本地文件
    33     String fileName = "Operator.doc".toString(); // 文件的默认保存名
    34     // 读到流中
    35     InputStream inStream = new FileInputStream("c:/Operator.doc");// 文件的存放路径
    36     // 设置输出的格式
    37     response.reset();
    38     response.setContentType("bin");
    39     response.addHeader("Content-Disposition", "attachment; filename="" + fileName + """);
    40     // 循环取出流中的数据
    41     byte[] b = new byte[100];
    42     int len;
    43     try {
    44       while ((len = inStream.read(b)) > 0)
    45         response.getOutputStream().write(b, 0, len);
    46       inStream.close();
    47     } catch (IOException e) {
    48       e.printStackTrace();
    49     }
    50   }
    51  
    52   public void downloadNet(HttpServletResponse response) throws MalformedURLException {
    53     // 下载网络文件
    54     int bytesum = 0;
    55     int byteread = 0;
    56  
    57     URL url = new URL("windine.blogdriver.com/logo.gif");
    58  
    59     try {
    60       URLConnection conn = url.openConnection();
    61       InputStream inStream = conn.getInputStream();
    62       FileOutputStream fs = new FileOutputStream("c:/abc.gif");
    63  
    64       byte[] buffer = new byte[1204];
    65       int length;
    66       while ((byteread = inStream.read(buffer)) != -1) {
    67         bytesum += byteread;
    68         System.out.println(bytesum);
    69         fs.write(buffer, 0, byteread);
    70       }
    71     } catch (FileNotFoundException e) {
    72       e.printStackTrace();
    73     } catch (IOException e) {
    74       e.printStackTrace();
    75     }
    76   }

    第二种方法:

     1 public void downLoad(String filePath, HttpServletResponse response, boolean isOnLine) throws Exception {
     2     File f = new File(filePath);
     3     if (!f.exists()) {
     4       response.sendError(404, "File not found!");
     5       return;
     6     }
     7     BufferedInputStream br = new BufferedInputStream(new FileInputStream(f));
     8     byte[] buf = new byte[1024];
     9     int len = 0;
    10  
    11     response.reset(); // 非常重要
    12     if (isOnLine) { // 在线打开方式
    13       URL u = new URL("file:///" + filePath);
    14       response.setContentType(u.openConnection().getContentType());
    15       response.setHeader("Content-Disposition", "inline; filename=" + f.getName());
    16       // 文件名应该编码成UTF-8
    17     } else { // 纯下载方式
    18       response.setContentType("application/x-msdownload");
    19       response.setHeader("Content-Disposition", "attachment; filename=" + f.getName());
    20     }
    21     OutputStream out = response.getOutputStream();
    22     while ((len = br.read(buf)) > 0)
    23       out.write(buf, 0, len);
    24     br.close();
    25     out.close();
    26   }
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  • 原文地址:https://www.cnblogs.com/xiaoyue1606bj/p/10985764.html
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