Java通用方法 -- 文件处理工具类

/**
*  文件处理工具类
*/
public class FileUtils {
    public static String FILENAME_PATTERN = "[a-zA-Z0-9_\\-\\|\\.\\u4e00-\\u9fa5]+";

    /**
     * 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);
        }
    }

    /**
     *  读文件
     * @param jsonPath 文件所在路径
     * @return
     */
    public static String readJson(String jsonPath){
        String jsonStr = "";
        try {
            File file = new File(jsonPath);
            FileReader fileReader = new FileReader(file);
//            Reader reader = new InputStreamReader(new FileInputStream(file),"Utf-8");
            Reader reader = new InputStreamReader(new FileInputStream(file));
            int ch = 0;
            StringBuffer sb = new StringBuffer();
            while ((ch = reader.read()) != -1) {
                sb.append((char) ch);
            }
            fileReader.close();
            reader.close();
            jsonStr = sb.toString();
            return jsonStr;
        } catch (Exception e) {
            return null;
        }
    }

    /**
     * 写数据到文件中
     *
     * @param data 数据
     * @return 目标文件
     * @throws IOException IO异常
     */
    public static String writeImportBytes(byte[] data) throws IOException
    {
        return writeBytes(data, RuoYiConfig.getImportPath());
    }

    /**
     * 写数据到文件中
     *
     * @param data 数据
     * @param uploadDir 目标文件
     * @return 目标文件
     * @throws IOException IO异常
     */
    public static String writeBytes(byte[] data, String uploadDir) throws IOException
    {
        FileOutputStream fos = null;
        String pathName = "";
        try
        {
            String extension = getFileExtendName(data);
            pathName = DateUtils.datePath() + "/" + IdUtils.fastUUID() + "." + extension;
            File file = FileUploadUtils.getAbsoluteFile(uploadDir, pathName);
            fos = new FileOutputStream(file);
            fos.write(data);
        }
        finally
        {
            IOUtils.close(fos);
        }
        return FileUploadUtils.getPathFileName(uploadDir, pathName);
    }

    /**
     * 写文件
     * @param path json文件路径
     * @param str json数据
     * @return
     * @throws IOException
     */
    public static void writeJson(String path,String str) throws IOException {
        FileWriter fw = new FileWriter(path);
        PrintWriter out = new PrintWriter(fw);
        out.write(str);
        out.println();
        fw.close();
        out.close();
    }

    /**
     * 删除文件
     *
     * @param filePath 文件
     * @return
     */
    public static boolean deleteFile(String filePath) {
        boolean flag = false;
        File file = new File(filePath);
        // 路径为文件且不为空则进行删除
        if (file.isFile() && file.exists()) {
            file.delete();
            flag = true;
        }
        return flag;
    }

    /**
     * 文件名称验证
     *
     * @param filename 文件名称
     * @return true 正常 false 非法
     */
    public static boolean isValidFilename(String filename) {
        return filename.matches(FILENAME_PATTERN);
    }

    /**
     * 检查文件是否可下载
     *
     * @param resource 需要下载的文件
     * @return true 正常 false 非法
     */
    public static boolean checkAllowDownload(String resource) {
        // 禁止目录上跳级别
        if (StringUtils.contains(resource, "..")) {
            return false;
        }

        // 检查允许下载的文件规则
        if (ArrayUtils.contains(MimeTypeUtils.DEFAULT_ALLOWED_EXTENSION, FileTypeUtils.getFileType(resource))) {
            return true;
        }

        // 不在允许下载的文件规则
        return false;
    }

    /**
     * 下载文件名重新编码
     *
     * @param request  请求对象
     * @param fileName 文件名
     * @return 编码后的文件名
     */
    public static String setFileDownloadHeader(HttpServletRequest request, String fileName) throws UnsupportedEncodingException {
        final String agent = request.getHeader("USER-AGENT");
        String filename = fileName;
        if (agent.contains("MSIE")) {
            // IE浏览器
            filename = URLEncoder.encode(filename, "utf-8");
            filename = filename.replace("+", " ");
        } else if (agent.contains("Firefox")) {
            // 火狐浏览器
            filename = new String(fileName.getBytes(), "ISO8859-1");
        } else if (agent.contains("Chrome")) {
            // google浏览器
            filename = URLEncoder.encode(filename, "utf-8");
        } else {
            // 其它浏览器
            filename = URLEncoder.encode(filename, "utf-8");
        }
        return filename;
    }

    /**
     * 下载文件名重新编码
     *
     * @param response     响应对象
     * @param realFileName 真实文件名
     * @return
     */
    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.setHeader("Content-disposition", contentDispositionValue.toString());
    }

    /**
     * 百分号编码工具方法
     *
     * @param s 需要百分号编码的字符串
     * @return 百分号编码后的字符串
     */
    public static String percentEncode(String s) throws UnsupportedEncodingException {
        String encode = URLEncoder.encode(s, StandardCharsets.UTF_8.toString());
        return encode.replaceAll("\\+", "%20");
    }
    /**
     * 获取图像后缀
     *
     * @param photoByte 图像数据
     * @return 后缀名
     */
    public static String getFileExtendName(byte[] photoByte)
    {
        String strFileExtendName = "jpg";
        if ((photoByte[0] == 71) && (photoByte[1] == 73) && (photoByte[2] == 70) && (photoByte[3] == 56)
                && ((photoByte[4] == 55) || (photoByte[4] == 57)) && (photoByte[5] == 97))
        {
            strFileExtendName = "gif";
        }
        else if ((photoByte[6] == 74) && (photoByte[7] == 70) && (photoByte[8] == 73) && (photoByte[9] == 70))
        {
            strFileExtendName = "jpg";
        }
        else if ((photoByte[0] == 66) && (photoByte[1] == 77))
        {
            strFileExtendName = "bmp";
        }
        else if ((photoByte[1] == 80) && (photoByte[2] == 78) && (photoByte[3] == 71))
        {
            strFileExtendName = "png";
        }
        return strFileExtendName;
    }
}