Java文件下载的几种方式

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();
         }
     }







//支持在线打开文件的一种方式   
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();
     }