code: public static long write(Writer writer, Reader reader) throws IOException {
          if (null == writer || null == reader)
              return 0;
  
          char[] cbuf = new char[BUF_SIZE];
          int len, count = 0;
          while (true) {
              len = reader.read(cbuf);
              if (len == -1)
                  break;
              writer.write(cbuf, 0, len);
              count += len;
          }
          return count;
      }
docs: 将文本输入流写入一个文本输出流。块大小为 8192
  <p>
  <b style=color:red>注意</b>，它并不会关闭输入/出流
  
  @param writer
  输出流
  @param reader
  输入流
  @throws IOException