java实现文件下载功能

淩亂°似流年 2021-06-22 15:37 616阅读 0赞

第一种方法：

public HttpServletResponse download(String path, HttpServletResponse response) {
        try {
          // path是指欲下载的文件的路径。
          File file = new File(path);
          // 取得文件名。
          String filename = file.getName();
          // 取得文件的后缀名。
          String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase();
     
          // 以流的形式下载文件。
          InputStream fis = new BufferedInputStream(new FileInputStream(path));
          byte[] buffer = new byte[fis.available()];
          fis.read(buffer);
          fis.close();
          // 清空response
          response.reset();
          // 设置response的Header
          response.addHeader("Content-Disposition", "attachment;filename=" + new String(filename.getBytes()));
          response.addHeader("Content-Length", "" + file.length());
          OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
          response.setContentType("application/octet-stream");
          toClient.write(buffer);
          toClient.flush();
          toClient.close();
        } catch (IOException ex) {
          ex.printStackTrace();
        }
        return response;
      }
     
      public void downloadLocal(HttpServletResponse response) throws FileNotFoundException {
        // 下载本地文件
        String fileName = "Operator.doc".toString(); // 文件的默认保存名
        // 读到流中
        InputStream inStream = new FileInputStream("c:/Operator.doc");// 文件的存放路径
        // 设置输出的格式
        response.reset();
        response.setContentType("bin");
        response.addHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
        // 循环取出流中的数据
        byte[] b = new byte[100];
        int len;
        try {
          while ((len = inStream.read(b)) > 0)
            response.getOutputStream().write(b, 0, len);
          inStream.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
     
      public void downloadNet(HttpServletResponse response) throws MalformedURLException {
        // 下载网络文件
        int bytesum = 0;
        int byteread = 0;
     
        URL url = new URL("windine.blogdriver.com/logo.gif");
     
        try {
          URLConnection conn = url.openConnection();
          InputStream inStream = conn.getInputStream();
          FileOutputStream fs = new FileOutputStream("c:/abc.gif");
     
          byte[] buffer = new byte[1204];
          int length;
          while ((byteread = inStream.read(buffer)) != -1) {
            bytesum += byteread;
            System.out.println(bytesum);
            fs.write(buffer, 0, byteread);
          }
        } catch (FileNotFoundException e) {
          e.printStackTrace();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }

第二种方法：

public void downLoad(String filePath, HttpServletResponse response, boolean isOnLine) throws Exception {
        File f = new File(filePath);
        if (!f.exists()) {
          response.sendError(404, "File not found!");
          return;
        }
        BufferedInputStream br = new BufferedInputStream(new FileInputStream(f));
        byte[] buf = new byte[1024];
        int len = 0;
     
        response.reset(); // 非常重要
        if (isOnLine) { // 在线打开方式
          URL u = new URL("file:///" + filePath);
          response.setContentType(u.openConnection().getContentType());
          response.setHeader("Content-Disposition", "inline; filename=" + f.getName());
          // 文件名应该编码成UTF-8
        } else { // 纯下载方式
          response.setContentType("application/x-msdownload");
          response.setHeader("Content-Disposition", "attachment; filename=" + f.getName());
        }
        OutputStream out = response.getOutputStream();
        while ((len = br.read(buf)) > 0)
          out.write(buf, 0, len);
        br.close();
        out.close();
      }