向服务器请求下载文件

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public class ResponseDownloadUtils {
    private static Logger log = LoggerFactory.getLogger(ResponseDownloadUtils.class);

    /**
     * @Title: download
     * @Description: 
     * @param response
     * @param path
     * @throws Exception
     * @date 2018-3-9 下午4:12:53
     */
    public static void download(HttpServletResponse response, String path) throws Exception {
        File f = new File(path);
        download(response, f, f.getName());
    }

    /**
     * @Title: download
     * @Description: 
     * @param response
     * @param path
     * @param fileName
     * @throws Exception
     * @date 2018-3-9 下午4:13:01
     */
    public static void download(HttpServletResponse response, String path, String fileName) throws Exception {
        File f = new File(path);
        download(response, f, fileName);
    }

    /**
     * @Title: download
     * @Description: 
     * @param response
     * @param file
     * @param fileName
     * @throws Exception
     * @date 2018-3-9 下午4:13:13
     */
    public static void download(HttpServletResponse response, File file, String fileName) throws Exception {
        File f = file;
        if (!f.exists()) {
            return;
        }
        download(response, new FileInputStream(f), fileName);
    }

    /**
     * @Title: download
     * @Description: 
     * @param response
     * @param fis
     * @param fileName
     * @date 2018-3-9 下午4:13:23
     */
    public static void download(HttpServletResponse response, FileInputStream fis, String fileName) {
        BufferedInputStream br = null;
        OutputStream out = null;
        try {
            if (fis == null) {
                response.sendError(404, "File not found!");
                return;
            }
            br = new BufferedInputStream(fis);
            byte[] buf = new byte[1024];
            int len = 0;
            response.reset();
            String fileName2 = new String(fileName.getBytes(), "ISO8859-1");
            response.setContentType("application/x-msdownload");
            response.setHeader("Content-Disposition", "attachment; filename=" + fileName2);
            out = response.getOutputStream();
            while ((len = br.read(buf)) != -1)
                out.write(buf, 0, len);
            out.flush();
            br.close();
            out.close();
        } catch (Exception ex) {
            ex.printStackTrace();
        } finally {
            try {
                if (br != null)
                    br.close();
                if (out != null)
                    out.close();
            } catch (IOException e) {
                log.error(ExceptionUtils.getStackTrace(e));
            }
        }
    }
}