关于下载

private static void downloadFile(String url, File outputFile) { 
  try {        URL u = new URL(url); 
      URLConnection conn = u.openConnection(); 
      int contentLength = conn.getContentLength(); 
 
      DataInputStream stream = new DataInputStream(u.openStream()); 
 
        byte[] buffer = new byte[contentLength]; 
        stream.readFully(buffer); 
        stream.close(); 
 
        DataOutputStream fos = new DataOutputStream(new FileOutputStream(outputFile)); 
        fos.write(buffer); 
        fos.flush(); 
        fos.close(); 
  } catch(FileNotFoundException e) { 
      return; // swallow a 404 
  } catch (IOException e) { 
      return; // swallow a 404 
  } 
}