//将流的内容写入文件 此方法会自动关闭输入流
    try {
      String str = "writeFromStreamTest内容1 \n writeFromStreamTest内容2";
      byte[] sb = str.getBytes();
      //内存读写流 不用回收关闭
      ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(sb);
      FileUtil.writeFromStream(byteArrayInputStream,"C:\\Users\\Administrator\\Desktop\\xuzhu\\writeFromStreamTest.txt");
    }catch (IORuntimeException e){
      //抛出一个运行时异常(直接停止掉程序)
      throw new RuntimeException("运行时异常",e);
    }