java后端上传文件到服务器，下载服务器文件到本地

上传文件

  /**
     * 根据文件路径上传
     *
     * @param baseDir 相对应用的基目录
     * @param file 上传的文件
     * @return 文件名称
     * @throws IOException
     */
    public static final String upload(String baseDir, MultipartFile file) throws IOException
    {
        try
        {
            return upload(baseDir, file);
        }
        catch (Exception e)
        {
            throw new IOException(e.getMessage(), e);
        }
    }

/**
     * 文件上传
     *
     * @param baseDir 相对应用的基目录
     * @param file 上传的文件
     * @return 返回上传成功的文件名
     * @throws FileSizeLimitExceededException 如果超出最大大小
     * @throws FileNameLengthLimitExceededException 文件名太长
     * @throws IOException 比如读写文件出错时
     * @throws InvalidExtensionException 文件校验异常
     */
    public static final String upload(String baseDir, MultipartFile file)
            throws IOException
    {
        String fileName = extractFilename(file);
        String absPath = getAbsoluteFile(baseDir, fileName).getAbsolutePath();
        file.transferTo(Paths.get(absPath));
        return getPathFileName(baseDir, fileName);
    }


/**
     * 编码文件名
     */
    public static final String extractFilename(MultipartFile file)
    {
        return StringUtils.format("{}/{}_{}.{}", DateUtils.datePath(),
                FilenameUtils.getBaseName(file.getOriginalFilename()), Seq.getId(Seq.uploadSeqType), getExtension(file));
    }


 public static final File getAbsoluteFile(String uploadDir, String fileName) throws IOException
    {
        File desc = new File(uploadDir + File.separator + fileName);

        if (!desc.exists())
        {
            if (!desc.getParentFile().exists())
            {
                desc.getParentFile().mkdirs();
            }
        }
        return desc;
    }


public static final String getPathFileName(String uploadDir, String fileName) throws IOException
    {
        int dirLastIndex = RuoYiConfig.getProfile().length() + 1;
        String currentDir = StringUtils.substring(uploadDir, dirLastIndex);
        return Constants.RESOURCE_PREFIX + "/" + currentDir + "/" + fileName;
    }

 

 

下载文件到本地

/**
     * 通用下载请求
     * 
     * @param fileName 文件名称
     * @param path     文件路径
     * @param response
     * @param request
     */
    @GetMapping("/download")
    public void fileDownload(String fileName, String path, HttpServletResponse response, HttpServletRequest request)
    {
        try
        {
            String realFileName = System.currentTimeMillis() + fileName.substring(fileName.indexOf("_") + 1);
            String filePath = path + fileName;
            response.setContentType(MediaType.APPLICATION_OCTET_STREAM_VALUE);
            setAttachmentResponseHeader(response, realFileName);
            writeBytes(filePath, response.getOutputStream());
        }
        catch (Exception e)
        {
            log.error("下载文件失败", e);
        }
    }

/**
 * 下载文件名重新编码
 *
 * @param response 响应对象
 * @param realFileName 真实文件名
 */
public static void setAttachmentResponseHeader(HttpServletResponse response, String realFileName) throws UnsupportedEncodingException
{
    String percentEncodedFileName = percentEncode(realFileName);

    StringBuilder contentDispositionValue = new StringBuilder();
    contentDispositionValue.append("attachment; filename=")
            .append(percentEncodedFileName)
            .append(";")
            .append("filename*=")
            .append("utf-8''")
            .append(percentEncodedFileName);

    response.addHeader("Access-Control-Expose-Headers", "Content-Disposition,download-filename");
    response.setHeader("Content-disposition", contentDispositionValue.toString());
    response.setHeader("download-filename", percentEncodedFileName);
}

/**
 * 输出指定文件的byte数组
 * 
 * @param filePath 文件路径
 * @param os 输出流
 * @return
 */
public static void writeBytes(String filePath, OutputStream os) throws IOException
{
    FileInputStream fis = null;
    try
    {
        File file = new File(filePath);
        if (!file.exists())
        {
            throw new FileNotFoundException(filePath);
        }
        fis = new FileInputStream(file);
        byte[] b = new byte[1024];
        int length;
        while ((length = fis.read(b)) > 0)
        {
            os.write(b, 0, length);
        }
    }
    catch (IOException e)
    {
        throw e;
    }
    finally
    {
        IOUtils.close(os);
        IOUtils.close(fis);
    }
}