文件缓冲流的方式

一下文件，防止没有权限，先复制到临时目录，进行下载，下载完成删除临时文件。

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public void fileDownload(@RequestParam(value = "filePath") String filePath) {
        logger.info("download the file param--------filePath:" + filePath);
        String fileName = "";
        int index = filePath.lastIndexOf("/");
        if (index != -1) {
            fileName = filePath.substring(index + 1);
        }
        try {
            String username = getLoginUserName();
            String user_dir = ConfigUtil.getInstance().getAppformConfig("USERS_DIR_UPLOAD_TEMP");
            String tmpDir = user_dir + File.separator + username + File.separator + ".restFileTmp" + File.separator + "." + System.currentTimeMillis();
            if (createTmpDir(tmpDir)) {
                logger.info(TAG + "创建临时目录文件" + tmpDir);
                //移动文件
                List<String> params = new ArrayList<>();
                params.add("-R");
                params.add("-p");
                params.add(filePath);
                params.add(tmpDir + File.separator);
                CmdResult result = client.executeCmd("cp", params, null, "root");

                List<String> chmodParams = new ArrayList<>();
                chmodParams.add("-R");
                chmodParams.add("777");
                chmodParams.add(tmpDir + File.separator + fileName);
                CmdResult chmodResult = client.executeCmd("chmod", chmodParams, null, "root");
                if (result.getExitCode() != 0 || chmodResult.getExitCode() != 0) {
                    logger.info("move file  exit code = " + result.getExitCode() + ";err=" + result.getStderr() + ";out=" + result.getStdout());
                    logger.info("chmod 777 file  exit code = " + chmodResult.getExitCode() + ";err=" + chmodResult.getStderr() + ";out=" + chmodResult.getStdout());
                    throw new RuntimeException("移动文件异常！");
                }
            } else {
                logger.error(TAG + "创建临时文件错误");
                throw new RuntimeException("创建临时文件错误");
            }
            File tmpFile = new File(tmpDir, fileName);
            if (!tmpFile.exists() || !tmpFile.isFile()) {
                logger.error(TAG + "文件不存在");
                throw new RuntimeException("文件路径错误");
            }
            response.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(fileName, "UTF-8"));
            try (FileInputStream fileInputStream = new FileInputStream(tmpFile);
                 BufferedInputStream bufferedInputStream = new BufferedInputStream(fileInputStream);
                 BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(response.getOutputStream())) {
                byte[] buffer = new byte[8192];
                int bytesRead;
                while ((bytesRead = bufferedInputStream.read(buffer)) != -1) {
                    bufferedOutputStream.write(buffer, 0, bytesRead);
                }
            } catch (IOException e) {
                logger.error(TAG + "下载文件过程发生错误" + e.getMessage() + e);
                throw new RuntimeException("下载文件过程发生错误", e);
            }

            List<String> params = new ArrayList<>();
            params.add("-rf");
            params.add(tmpDir);
            CmdResult rmResult = client.executeCmd("rm", params, null, "root");
            if (rmResult.getExitCode() != 0) {
                logger.error(TAG + "rm tmpFile  exit code = " + rmResult.getExitCode() + ";err=" + rmResult.getStderr() + ";out=" + rmResult.getStdout());
            }
        } catch (Exception e) {
            logger.error(TAG + e.getMessage() + e);
            throw new RuntimeException("下载文件错误！" + e.getMessage());
        }
    }