public static File downLoad(String serverPath,String savedPath,ProgressDialog dialog){                try {                                        URL url=new URL(serverPath);                    HttpURLConnection _conn=(HttpURLConnection) url.openConnection();                    _conn.setRequestMethod("GET");                    _conn.setConnectTimeout(5000);                    int code=_conn.getResponseCode();                    if(code==200){                        //设置进度条的长度                        dialog.setMax(_conn.getContentLength());                        InputStream is=_conn.getInputStream();                        File _file=new File(savedPath);                        FileOutputStream _FileOutputStream=new FileOutputStream(_file);                        int len=0;                        byte[] buffer= new byte[1024];                        int _total=0;                        while((len=is.read(buffer))!=-1){                            _FileOutputStream.write(buffer, 0,len);                            _total+=len;                            dialog.setProgress(_total);                            Thread.sleep(20);                        }                        _FileOutputStream.flush();                        _FileOutputStream.close();                        is.close();                        return _file;                    }else {                        return null;                    }                } catch (Exception e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    return null;                }                                            }