我使用 commons-io CountingInputStream ，它可以帮到你。一个完整而简单的例子：

I'd use a commons-io CountingInputStream, which would do the job for you. A full but trivial example:

public long countContent(URL feedurl) {
  CountingInputStream counter = null;
  try {
     HttpURLConnection con = (HttpURLConnection) feedurl.openConnection();
     counter = new CountingInputStream(con.getInputStream());
     String output = IOUtils.toString(counter);
     return counter.getByteCount();
  } catch (IOException ex) {
     throw new RuntimeException(ex);
  } finally {
     IOUtils.closeQuietly(counter);
  }
}