如果要在写入时捕获字节，请使用 io.MultiWriter ， bytes.Buffer 作为第二作者。

If you want to capture the bytes as they are written, use an io.MultiWriter with a bytes.Buffer as the second writer.

var buf bytes.Buffer
w := io.MultiWriter(codeFile, &buf)

或者在stdout上查看文件：

or to see the file on stdout as it's written:

w := io.MultiWriter(codeFile, os.Stdout)

否则，如果你想要重新读取同一个文件，你需要在写完后回头找：

Otherwise, if you want to re-read the same file, you need to seek back to the start after writing:

codeFile.Seek(0, 0)