取得inputStream的长度

1.网络下载文件

 URL url = new URL(strUrl);

 HttpURLConnection httpconn = (HttpURLConnection)url.openConnection();  

 httpconn.getContentLength();

2.本地文件

 InputStream inputStream = urlCon.getInputStream();

 inputStream.available();

来源：http://hold-on.iteye.com/blog/1017449