/**
   * 示例
   * @throws UnsupportedEncodingException 
   * @throws FileNotFoundException 
   */
  @SuppressWarnings("resource")
  public static void main(String[] args) throws UnsupportedEncodingException, FileNotFoundException {
    String strImg = getImageStr("Z:\\水印\\2.bmp");
    System.out.println(strImg);
    File file = new File("z://1.txt");
    FileOutputStream fos = new FileOutputStream(file);
    OutputStreamWriter osw = new OutputStreamWriter(fos, "UTF-8");
    try {
      osw.write(strImg);
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    //generateImage(strImg, "Z:\\水印\\444.bmp");
    
  }

**
   * @Description: 根據圖片地址轉換為base64編碼字符串
   * @Author:
   * @CreateTime:
   * @return
   */
  public static String getImageStr(String imgFile) {
    InputStream inputStream = null;
    byte[] data = null;
    try {
      inputStream = new FileInputStream(imgFile);
      data = new byte[inputStream.available()];
      inputStream.read(data);
      inputStream.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
    // 加密
    Encoder encoder = Base64.getEncoder();
    return encoder.encodeToString(data);
  }

/**
   * @Description: 將base64編碼字符串轉換為圖片
   * @Author: 
   * @CreateTime: 
   * @param imgStr base64編碼字符串
   * @param path 圖片路徑-具體到文件
   * @return
  */
  public static boolean generateImage(String imgStr, String path) {
      if (imgStr == null)
        return false;
      // 解密
      try {
        Decoder decoder = Base64.getDecoder();
        byte[] b = decoder.decode(imgStr);
        // 處理數據
        for (int i = 0; i < b.length; ++i) {
          if (b[i] < 0) {
          b[i] += 256;
          }
        }
        OutputStream out = new FileOutputStream(path);
        out.write(b);
        out.flush();
        out.close();
        return true;
      } catch (IOException e) {
        return false;
      }
  }