下载网络文件HttpURLConnection.getConte

AsyncTask+HttpURLConnection进行文件下载

   HttpURLConnection conn = (HttpURLConnection)url.openConnection();
   conn.connect();
   int length = conn.getContentLength();

当测试时会报错。经过Debug才发现是 length=-1,后来几番搜获后发现在默认情况下，HttpURLConnection 使用 gzip方式获取。
我们只需要设置

HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn .setRequestProperty("Accept-Encoding", "identity"); 
conn.connect();
int length = conn.getContentLength();
InputStream is = conn.getInputStream();

改变接收文件的格式便可。