Java 中文件下载的几种应用

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(".") + ).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[];

        int len;

        try {

            while ((len = inStream.read(b)) > )

                response.getOutputStream().write(b, , len);

            inStream.close();

        } catch (IOException e) {

            e.printStackTrace();

        }

    }

    public void downloadNet(HttpServletResponse response) throws MalformedURLException {

        // 下载网络文件

        int bytesum = ;

        int byteread = ;

        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[];

            int length;

            while ((byteread = inStream.read(buffer)) != -) {

                bytesum += byteread;

                System.out.println(bytesum);

                fs.write(buffer, , byteread);

            }

        } catch (FileNotFoundException e) {

            e.printStackTrace();

        } catch (IOException e) {

            e.printStackTrace();

        }

    }

 public void downLoad(String filePath, HttpServletResponse response, boolean isOnLine) throws Exception {

        File f = new File(filePath);

        if (!f.exists()) {

            response.sendError(, "File not found!");

            return;

        }

        BufferedInputStream br = new BufferedInputStream(new FileInputStream(f));

        byte[] buf = new byte[];

        int len = ;

        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)) > )

            out.write(buf, , len);

        br.close();

        out.close();

    }