springmvc通过ResponseEntity实现文件下载

在springmvc中实现文件下载一般都是借助HttpServletResponse的getOutputStream()方法实现的，除此之外还可以通过ResponseEntity实现：

 	@RequestMapping(value = "/downloadxx.do", method = RequestMethod.GET)
    public ResponseEntity<InputStreamResource> downloadxx(HttpServletRequest request, HttpServletResponse response) throws IOException {
        String filePath = "/download/xx.zip";
        ClassPathResource file = new ClassPathResource(filePath);
        // 文件名编码，解决乱码问题
        String fileName = file.getFilename();
        // 解决文件名乱码问题
        // String fileName = URLEncoder.encode(file.getFilename(), StandardCharsets.UTF_8.toString());
        String userAgentString = request.getHeader("User-Agent");
        String browser = UserAgent.parseUserAgentString(userAgentString).getBrowser().getGroup().getName();
        if (browser.equals("Chrome") || browser.equals("Internet Exploer") || browser.equals("Safari")) {
            fileName = URLEncoder.encode(fileName, "utf-8").replaceAll("\+", "%20");
        } else {
            fileName = MimeUtility.decodeText(fileName); // encodeWord(fileName);
        }

        HttpHeaders headers = new HttpHeaders();
        headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
        headers.add("Content-Disposition", String.format("attachment; filename="%s"", fileName));
        headers.add("Pragma", "no-cache");
        headers.add("Expires", "0");
        return ResponseEntity.ok().headers(headers).contentLength(file.contentLength())
            .contentType(MediaType.parseMediaType("application/octet-stream"))
            .body(new InputStreamResource(file.getInputStream()));
    }